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Vilardi KJ, Johnston J, Dai Z, Cotto I, Tuttle E, Patterson A, Stubbins A, Pieper KJ, Pinto AJ. Nitrogen source influences the interactions of comammox bacteria with aerobic nitrifiers. Microbiol Spectr 2024:e0318123. [PMID: 38511951 DOI: 10.1128/spectrum.03181-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 02/29/2024] [Indexed: 03/22/2024] Open
Abstract
While the co-existence of comammox Nitrospira with canonical nitrifiers is well documented in diverse ecosystems, there is still a dearth of knowledge about the mechanisms underpinning their interactions. Understanding these interaction mechanisms is important as they may play a critical role in governing nitrogen biotransformation in natural and engineered ecosystems. In this study, we tested the ability of two environmentally relevant factors (nitrogen source and availability) to shape interactions between strict ammonia and nitrite-oxidizing bacteria and comammox Nitrospira in continuous flow column reactors. The composition of inorganic nitrogen species in reactors fed either ammonia or urea was similar during the lowest input nitrogen concentration (1 mg-N/L), but higher concentrations (2 and 4 mg-N/L) promoted significant differences in nitrogen species composition and nitrifier abundances. The abundance and diversity of comammox Nitrospira were dependent on both nitrogen source and input concentrations as multiple comammox Nitrospira populations were preferentially enriched in the urea-fed system. In contrast, their abundance was reduced in response to higher nitrogen concentrations in the ammonia-fed system. The preferential enrichment of comammox Nitrospira in the urea-fed system could be associated with their ureolytic activity calibrated to their ammonia oxidation rates, thus minimizing ammonia accumulation, which may be partially inhibitory. However, an increased abundance of comammox Nitrospira was not associated with a reduced abundance of nitrite oxidizers in the urea-fed system while a negative correlation was found between them in the ammonia-fed system, the latter dynamic likely emerging from reduced availability of nitrite to strict nitrite oxidizers at low ammonia concentrations. IMPORTANCE Nitrification is an essential biological process in drinking water and wastewater treatment systems for treating nitrogen pollution. The discovery of comammox Nitrospira and their detection alongside canonical nitrifiers in these engineered ecosystems have made it necessary to understand the environmental conditions that regulate their abundance and activity relative to other better-studied nitrifiers. This study aimed to evaluate two important factors that could potentially influence the behavior of nitrifying bacteria and, therefore, impact nitrification processes. Column reactors fed with either ammonia or urea were systematically monitored to capture changes in nitrogen biotransformation and the nitrifying community as a function of influent nitrogen concentration, nitrogen source, and reactor depth. Our findings show that with increased ammonia availability, comammox Nitrospira decreased in abundance while nitrite oxidizers abundance increased. Yet, in systems with increasing urea availability, comammox Nitrospira abundance and diversity increased without an associated reduction in the abundance of canonical nitrifiers.
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Affiliation(s)
- Katherine Jeanne Vilardi
- Department of Civil and Environmental Engineering, Northeastern University, Boston, Massachusetts, USA
| | - Juliet Johnston
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Zihan Dai
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Irmarie Cotto
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Erin Tuttle
- Department of Marine and Environmental Sciences, Northeastern University, Boston, Massachusetts, USA
| | - Ariana Patterson
- Department of Civil and Environmental Engineering, Northeastern University, Boston, Massachusetts, USA
| | - Aron Stubbins
- Department of Civil and Environmental Engineering, Northeastern University, Boston, Massachusetts, USA
- Department of Marine and Environmental Sciences, Northeastern University, Boston, Massachusetts, USA
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts, USA
| | - Kelsey J Pieper
- Department of Civil and Environmental Engineering, Northeastern University, Boston, Massachusetts, USA
| | - Ameet J Pinto
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
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Ghimire-Kafle S, Weaver ME, Kimbrel MP, Bollmann A. Competition between ammonia-oxidizing archaea and complete ammonia oxidizers from freshwater environments. Appl Environ Microbiol 2024; 90:e0169823. [PMID: 38349190 PMCID: PMC10952389 DOI: 10.1128/aem.01698-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 01/11/2024] [Indexed: 03/21/2024] Open
Abstract
Aerobic ammonia oxidizers (AOs) are prokaryotic microorganisms that contribute to the global nitrogen cycle by performing the first step of nitrification, the oxidation of ammonium to nitrite and nitrate. While aerobic AOs are found ubiquitously, their distribution is controlled by key environmental conditions such as substrate (ammonium) availability. Ammonia-oxidizing archaea (AOA) and complete ammonia oxidizers (comammox) are generally found in oligotrophic environments with low ammonium availability. However, whether AOA and comammox share these habitats or outcompete each other is not well understood. We assessed the competition for ammonium between an AOA and comammox enriched from the freshwater Lake Burr Oak. The AOA enrichment culture (AOA-BO1) contained Nitrosarchaeum sp. BO1 as the ammonia oxidizer and Nitrospira sp. BO1 as the nitrite oxidizer. The comammox enrichment BO4 (cmx-BO4) contained the comammox strain Nitrospira sp. BO4. The competition experiments were performed either in continuous cultivation with ammonium as a growth-limiting substrate or in batch cultivation with initial ammonium concentrations of 50 and 500 µM. Regardless of the ammonium concentration, Nitrospira sp. BO4 outcompeted Nitrosarchaeum sp. BO1 under all tested conditions. The dominance of Nitrospira sp. BO4 could be explained by the ability of comammox to generate more energy through the complete oxidation of ammonia to nitrate and their more efficient carbon fixation pathway-the reductive tricarboxylic acid cycle. Our results are supported by the higher abundance of comammox compared to AOA in the sediment of Lake Burr Oak. IMPORTANCE Nitrification is a key process in the global nitrogen cycle. Aerobic ammonia oxidizers play a central role in the nitrogen cycle by performing the first step of nitrification. Ammonia-oxidizing archaea (AOA) and complete ammonia oxidizers (comammox) are the dominant nitrifiers in environments with low ammonium availability. While AOA have been studied for almost 20 years, comammox were only discovered 8 years ago. Until now, there has been a gap in our understanding of whether AOA and comammox can co-exist or if one strain would be dominant under ammonium-limiting conditions. Here, we present the first study characterizing the competition between freshwater AOA and comammox under varying substrate concentrations. Our results will help in elucidating the niches of two key nitrifiers in freshwater lakes.
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Affiliation(s)
| | - Matt E. Weaver
- Department of Microbiology, Miami University, Oxford, Ohio, USA
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Nguyen Quoc B, Peng B, De Clippeleir H, Winkler MKH. Case study: Bioaugmenting the comammox dominated biomass from B-stage to enhance nitrification in A-stage at Blue Plains AWWTP. Water Environ Res 2024; 96:e11005. [PMID: 38407520 DOI: 10.1002/wer.11005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 02/27/2024]
Abstract
A comprehensive case study was undertaken at the Blue Plains wastewater treatment plant (WWTP) to explore the bioaugmentation technique of introducing nitrifying sludge into the non-nitrifying stage over the course of two operational years. This innovative approach involved the return of waste activated sludge (WAS) from the biological nutrient removal (BNR) system to enhance the nitrification in the high carbon removal rate system. The complete ammonia oxidizer (comammox) Nitrospira Nitrosa was identified as the main nitrifier in the system. Bioaugmentation was shown to be successful as nitrifiers returned from BNR were able to increase the nitrifying activity of the high carbon removal rate system. There was a positive correlation between returned sludge from the BNR stage and the specific total kjeldahl nitrogen (TKN) removal rate in A stage. The bioaugmentation process resulted in a remarkable threefold increase in the specific TKN removal rate within the A stage. Result suggested that recycling of WAS is a simple technique to bio-augment a low SRT system with nitrifiers and add ammonia oxidation to a previously non-nitrifying stage. The results from this case study hold the potential for applicable implications for other WWTPs that have a similar operational scheme to Blue Plains, allowing them to reuse WAS from the B stage, previously considered waste, to enhance nitrification and thus improving overall nitrogen removal performance. PRACTITIONER POINTS: Comammox identifying as main nitrifier in the B stage. Comammox enriched sludge from B stage successfully bio-augmented the East side of A stage up to threefold. Bioaugmentation of comammox in the West side of A stage was potentially inhibited by the gravity thickened overflow. Sludge returned from B stage to A stage can improve nitrification with a very minor retrofits and short startup times.
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Affiliation(s)
- Bao Nguyen Quoc
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
| | - Bo Peng
- DC Water and Sewer Authority, Washington, District of Columbia, USA
| | | | - Mari-Karoliina H Winkler
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
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Liu Q, Chen Y, Xu XW. Genomic insight into strategy, interaction and evolution of nitrifiers in metabolizing key labile-dissolved organic nitrogen in different environmental niches. Front Microbiol 2023; 14:1273211. [PMID: 38156017 PMCID: PMC10753782 DOI: 10.3389/fmicb.2023.1273211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 11/09/2023] [Indexed: 12/30/2023] Open
Abstract
Ammonia-oxidizing archaea (AOA) and bacteria (AOB), nitrite-oxidizing bacteria (NOB), and complete ammonia oxidizers (comammox) are responsible for nitrification in nature; however, some groups have been reported to utilize labile-dissolved organic nitrogen (LDON) for satisfying nitrogen demands. To understand the universality of their capacity of LDON metabolism, we collected 70 complete genomes of AOA, AOB, NOB, and comammox from typical environments for exploring their potentials in the metabolism of representative LDON (urea, polyamines, cyanate, taurine, glycine betaine, and methylamine). Genomic analyses showed that urea was the most popular LDON used by nitrifiers. Each group harbored unique urea transporter genes (AOA: dur3 and utp, AOB: utp, and NOB and comammox: urtABCDE and utp) accompanied by urease genes ureABC. The differentiation in the substrate affinity of these transporters implied the divergence of urea utilization efficiency in nitrifiers, potentially driving them into different niches. The cyanate transporter (cynABD and focA/nirC) and degradation (cynS) genes were detected mostly in NOB, indicating their preference for a wide range of nitrogen substrates to satisfy high nitrogen demands. The lack of genes involved in the metabolism of polyamines, taurine, glycine betaine, and methylamines in most of nitrifiers suggested that they were not able to serve as a source of ammonium, only if they were degraded or oxidized extracellularly as previously reported. The phylogenetic analyses assisted with comparisons of GC% and the Codon Adaptation Index between target genes and whole genomes of nitrifiers implied that urea metabolic genes dur3 and ureC in AOA evolved independently from bacteria during the transition from Thaumarchaeota to AOA, while utp in terrestrial AOA was acquired from bacteria via lateral gene transfer (LGT). Cyanate transporter genes cynS and focA/nirC detected only in a terrestrial AOA Candidadus Nitrsosphaera gargensis Ga9.2 could be gained synchronously with Nitrospira of NOB by an ancient LGT. Our results indicated that LDON utilization was a common feature in nitrifiers, but metabolic potentials were different among nitrifiers, possibly being intensely interacted with their niches, survival strategies, and evolutions.
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Affiliation(s)
- Qian Liu
- Donghai Laboratory, Zhoushan, Zhejiang, China
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- Ocean College, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yuhao Chen
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Xue-Wei Xu
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- Ocean College, Zhejiang University, Hangzhou, Zhejiang, China
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
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Ma B, LaPara TM, Kim T, Hozalski RM. Multi-scale Investigation of Ammonia-Oxidizing Microorganisms in Biofilters Used for Drinking Water Treatment. Environ Sci Technol 2023; 57:3833-3842. [PMID: 36811531 DOI: 10.1021/acs.est.2c06858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Ammonia-oxidizing microorganisms (AOMs) include ammonia-oxidizing bacteria (AOB), archaea (AOA), and Nitrospira spp. sublineage II capable of complete ammonia oxidation (comammox). These organisms can affect water quality not only by oxidizing ammonia to nitrite (or nitrate) but also by cometabolically degrading trace organic contaminants. In this study, the abundance and composition of AOM communities were investigated in full-scale biofilters at 14 facilities across North America and in pilot-scale biofilters operated for 18 months at a full-scale water treatment plant. In general, the relative abundance of AOM in most full-scale biofilters and in the pilot-scale biofilters was as follows: AOB > comammox Nitrospira > AOA. The abundance of AOB in the pilot-scale biofilters increased with increasing influent ammonia concentration and decreasing temperature, whereas AOA and comammox Nitrospira exhibited no correlations with these parameters. The biofilters affected AOM abundance in the water passing through the filters via collecting and shedding but exhibited a minor influence on the composition of AOB and Nitrospira sublineage II communities in the filtrate. Overall, this study highlights the relative importance of AOB and comammox Nitrospira compared to AOA in biofilters and the influence of filter influent water quality on AOM in biofilters and their release into the filtrate.
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Affiliation(s)
- Ben Ma
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, Minnesota 55455, United States
| | - Timothy M LaPara
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, Minnesota 55455, United States
- Biotechnology Institute, University of Minnesota, 1479 Gortner Avenue, Saint Paul, Minnesota 55108, United States
| | - Taegyu Kim
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, Minnesota 55455, United States
| | - Raymond M Hozalski
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, Minnesota 55455, United States
- Biotechnology Institute, University of Minnesota, 1479 Gortner Avenue, Saint Paul, Minnesota 55108, United States
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Liu YJ, Liu ZK, Jin SS, Deng HY, Shen JP, He JZ. Response of gene abundance of ammonia-oxidizing microorganisms and denitrifying microorganisms to nitrogen and phosphorus addition in subtropical forest. Ying Yong Sheng Tai Xue Bao 2023; 34:639-646. [PMID: 37087646 DOI: 10.13287/j.1001-9332.202303.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 04/24/2023]
Abstract
We conducted a nitrogen (N) and phosphorus (P) addition experiment in Qianjiangyuan National Park in 2015, to investigate the response of ammonia-oxidizing microorganisms and denitrifying microorganisms. There were four treatments, including N addition (N), P addition (P), NP, and control (CK). Soil samples were collected in April (wet season) and November (dry season) of 2021. The abundance of amoA gene of ammonia-oxidizing microorganisms (i.e., ammonia-oxidizing archaea, AOA; ammonia-oxidizing bacteria, AOB; comammox) and denitrifying microbial genes (i.e., nirS, nirK, and nosZ) were determined using quantitative PCR approach. The results showed that soil pH was significantly decreased by long-term N addition, while soil ammonium and nitrate contents were significantly increased. Soil available P and total P contents were significantly increased with the long-term P addition. The addition of N (N and NP treatments) significantly increased the abundance of AOB-amoA gene in both seasons, and reached the highest in the N treatment around 8.30×107 copies·g-1 dry soil. The abundance of AOA-amoA gene was significantly higher in the NP treatment than that in CK, with the highest value around 1.17×109 copies·g-1 dry soil. There was no significant difference in N-related gene abundances between two seasons except for the abundance of comammox-amoA. Nitrogen addition exerted significant effect on the abundance of AOB-amoA, nirK and nosZ genes, especially in wet season. Phosphorus addition exerted significant effect on the abundance of AOA-amoA and AOB-amoA genes in both seasons, but did not affect denitrifying gene abundances. Soil pH, ammonium, nitrate, available P, and soil water contents were the main factors affecting the abundance of soil N-related functional genes. In summary, the response of soil ammonia-oxidizing microorganisms and denitrifying microorganisms was more sensitive to N addition than to P addition. These findings shed new light for evaluating soil nutrient availability as well as their response mechanism to global change in subtropical forests.
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Affiliation(s)
- Yan-Ji Liu
- State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou 350007, China
- School of Geographical Sciences/School of Carbon Neutrality Future Technology, Fujian Normal University, Fuzhou 350007, China
| | - Zi-Kai Liu
- State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou 350007, China
- School of Geographical Sciences/School of Carbon Neutrality Future Technology, Fujian Normal University, Fuzhou 350007, China
| | - Sheng-Sheng Jin
- State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou 350007, China
- School of Geographical Sciences/School of Carbon Neutrality Future Technology, Fujian Normal University, Fuzhou 350007, China
| | - Hui-Yu Deng
- State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou 350007, China
- School of Geographical Sciences/School of Carbon Neutrality Future Technology, Fujian Normal University, Fuzhou 350007, China
| | - Ju-Pei Shen
- State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou 350007, China
- School of Geographical Sciences/School of Carbon Neutrality Future Technology, Fujian Normal University, Fuzhou 350007, China
| | - Ji-Zheng He
- State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou 350007, China
- School of Geographical Sciences/School of Carbon Neutrality Future Technology, Fujian Normal University, Fuzhou 350007, China
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Ghimire-Kafle S, Weaver ME Jr, Bollmann A. Ecophysiological and Genomic Characterization of the Freshwater Complete Ammonia Oxidizer Nitrospira sp. Strain BO4. Appl Environ Microbiol 2023; 89:e0196522. [PMID: 36719237 DOI: 10.1128/aem.01965-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Complete ammonia oxidizers (comammox) are a group of ubiquitous chemolithoautotrophic bacteria capable of deriving energy from the oxidation of ammonia to nitrate via nitrite. Here, we present a study characterizing the comammox strain Nitrospira sp. BO4 using a combination of cultivation-dependent and molecular methods. The enrichment culture BO4 was obtained from the sediment of Lake Burr Oak, a mesotrophic lake in eastern Ohio. The metagenome of the enrichment culture was sequenced, and a metagenome-assembled genome (MAG) was constructed for Nitrospira sp. BO4. The closest characterized relative of Nitrospira sp. BO4 was "Candidatus Nitrospira kreftii." All genes for ammonia and nitrite oxidation, reductive tricarboxylic acid (TCA) cycle, and other pathways of the central metabolism were detected. Nitrospira sp. BO4 used ammonia and oxidized it to nitrate with nitrite as the intermediate. The culture grew on initial ammonium concentrations between 0.01 and 3 mM with the highest rates observed at the lowest ammonium concentrations. Blue light completely inhibited the growth of Nitrospira sp. BO4, while white light reduced the growth and red light had no effect on the growth. Nitrospira sp. BO4 did not grow on nitrite as its sole substrate. When supplied with ammonium and nitrite, the culture utilized nitrite after most of the ammonium was consumed. In summary, the genomic information of Nitrospira sp. BO4 coupled with the growth experiments shows that Nitrospira sp. BO4 is a freshwater comammox species. Future research will focus on further characterization of the niches of comammox in freshwater environments. IMPORTANCE Nitrification is a key process in the global nitrogen cycle. Complete ammonia oxidizers (comammox) were discovered recently, and only three enrichment cultures and one pure culture have been characterized with respect to activity and growth under different conditions. The cultivated comammox strains were obtained from engineered systems such as a recirculating aquaculture system and hot water pipes. Here, we present the first study characterizing a comammox strain obtained from a mesotrophic freshwater lake. In freshwater environments, comammox coexist with ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). Our results will help elucidate physiological characteristics of comammox and the distribution and niche differentiation of different ammonia oxidizers in freshwater environments.
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Shao YH, Wu YW, Naufal M, Wu JH. Genome-centered metagenomics illuminates adaptations of core members to a partial Nitritation-Anammox bioreactor under periodic microaeration. Front Microbiol 2023; 14:1046769. [PMID: 36778888 PMCID: PMC9909701 DOI: 10.3389/fmicb.2023.1046769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 01/06/2023] [Indexed: 01/27/2023] Open
Abstract
The partial nitritation-anaerobic ammonium oxidation (anammox; PN-A) process has been considered a sustainable method for wastewater ammonium removal, with recent attempts to treat low-strength wastewater. However, how microbes adapt to the alternate microaerobic-anoxic operation of the process when treating low ammonium concentrations remains poorly understood. In this study, we applied a metagenomic approach to determine the genomic contents of core members in a PN-A reactor treating inorganic ammonium wastewater at loading as low as 0.0192 kg-N/m3/day. The metabolic traits of metagenome-assembled genomes from 18 core species were analyzed. Taxonomically diverse ammonia oxidizers, including two Nitrosomonas species, a comammox Nitrospira species, a novel Chloroflexota-related species, and two anammox bacteria, Ca. Brocadia and Ca. Jettenia, accounted for the PN-A reactions. The characteristics of a series of genes encoding class II ribonucleotide reductase, high-affinity bd-type terminal oxidase, and diverse antioxidant enzymes revealed that comammox Nitrospira has a superior adaptation ability over the competitors, which may confer the privileged partnership with anammox bacteria in the PN-A reactor. This finding is supported by the long-term monitoring experiment, showing the predominance of the comammox Nitrospira in the ammonia-oxidizing community. Metagenomic analysis of seven heterotrophs suggested that nitrate reduction is a common capability in potentially using endogenous carbohydrates and peptides to enhance nitrogen removals. The prevalence of class II ribonucleotide reductase and antioxidant enzymes genes may grant the adaptation to cyclically microaerobic/anoxic environments. The predominant heterotroph is affiliated with Chloroflexota; its genome encodes complete pathways for synthesizing vitamin B6 and methionine. By contrast, other than the two growth factors, Nitrospira and anammox bacteria are complementary to produce various vitamins and amino acids. Besides, the novel Chloroflexota-related ammonia oxidizer lacks corresponding genes for detoxifying the reactive oxygen species and thus requires the aid of co-existing members to alleviate oxidative stress. The analysis results forecast the exchanges of substrates and nutrients as well as the collective alleviation of oxidative stress among the core populations. The new findings of the genomic features and predicted microbial interplay shed light on microbial adaptation to intermittent microaeration specific to the PN-A reactor, which may aid in improving its application to low-strength ammonium wastewater.
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Affiliation(s)
- Yung-Hsien Shao
- Department of Environmental Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Wei Wu
- College of Medical Science and Technology, Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei, Taiwan
| | - Muhammad Naufal
- Department of Environmental Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Jer-Horng Wu
- Department of Environmental Engineering, National Cheng Kung University, Tainan, Taiwan,*Correspondence: Jer-Horng Wu, ✉
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Ohbayashi T, Wang Y, Aoyagi LN, Hara S, Tago K, Hayatsu M. Diversity of the Hydroxylamine Oxidoreductase (HAO) Gene and Its Enzyme Active Site in Agricultural Field Soils. Microbes Environ 2023; 38:ME23068. [PMID: 38092410 PMCID: PMC10728637 DOI: 10.1264/jsme2.me23068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 10/06/2023] [Indexed: 12/18/2023] Open
Abstract
Nitrification is a key process in the biogeochemical nitrogen cycle and a major emission source of the greenhouse gas nitrous oxide (N2O). The periplasmic enzyme hydroxylamine oxidoreductase (HAO) is involved in the oxidation of hydroxylamine to nitric oxide in the second step of nitrification, producing N2O as a byproduct. Its three-dimensional structure demonstrates that slight differences in HAO active site residues have inhibitor effects. Therefore, a more detailed understanding of the diversity of HAO active site residues in soil microorganisms is important for the development of novel nitrification inhibitors using structure-guided drug design. However, this has not yet been examined. In the present study, we investigated hao gene diversity in beta-proteobacterial ammonia-oxidizing bacteria (β-AOB) and complete ammonia-oxidizing (comammox; Nitrospira spp.) bacteria in agricultural fields using a clone library ana-lysis. A total of 1,949 hao gene sequences revealed that hao gene diversity in β-AOB and comammox bacteria was affected by the fertilizer treatment and field type, respectively. Moreover, hao sequences showed the almost complete conservation of the six HAO active site residues in both β-AOB and comammox bacteria. The diversity of nitrifying bacteria showed similarity between hao and amoA genes. The nxrB amplicon sequence revealed the dominance of Nitrospira cluster II in tea field soils. The present study is the first to reveal hao gene diversity in agricultural soils, which will accelerate the efficient screening of HAO inhibitors and evaluations of their suppressive effects on nitrification in agricultural soils.
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Affiliation(s)
- Tsubasa Ohbayashi
- Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), 305–8604, Tsukuba, Japan
| | - Yong Wang
- Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), 305–8604, Tsukuba, Japan
| | - Luciano Nobuhiro Aoyagi
- Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), 305–8604, Tsukuba, Japan
| | - Shintaro Hara
- Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), 305–8604, Tsukuba, Japan
| | - Kanako Tago
- Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), 305–8604, Tsukuba, Japan
| | - Masahito Hayatsu
- Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), 305–8604, Tsukuba, Japan
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Gottshall EY, Godfrey B, Li B, Abrahamson B, Qin W, Winkler M. Photoinhibition of comammox reaction in Nitrospira inopinata in a dose- and wavelength-dependent manner. Front Microbiol 2022; 13:1022899. [PMID: 36590435 PMCID: PMC9797979 DOI: 10.3389/fmicb.2022.1022899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 11/22/2022] [Indexed: 12/23/2022] Open
Abstract
Apparent contribution of complete ammonia-oxidizing organisms (comammox) to the global nitrogen cycle highlights the necessity for understanding niche differentiation of comammox bacteria among other ammonia oxidizers. While the high affinity for ammonia of the comammox species Nitrospira inopinata suggests their niche partitioning is expected to be centered in oligotrophic environments, their absence in nutrient-depleted environments (such as the oceans) suggests that other (abiotic) factors might control their distribution and spatial localization within microbial communities. Many ammonia- and nitrite-oxidizing organisms are sensitive to light; however, the photosensitivity of comammox has not been explored. Since comammox bacteria encode enzymatic machinery homologous to canonical ammonia-and nitrite-oxidizers, we hypothesized that comammox N. inopinata, the only available pure culture of this group of microorganisms, may be inhibited by illumination in a similar manner. We evaluated the impact of light intensity, wavelength, and duration on the degree of photoinhibition for cultures of the comammox species N. inopinata and the soil ammonia-oxidizing archaea Nitrososphaera viennensis. Both species were highly sensitive to light. Interestingly, mimicking diurnal light exposure caused an uncoupling of ammonia and nitrite oxidation in N. inopinata, indicating nitrite oxidation might be more sensitive to light exposure than ammonia oxidation. It is likely that light influences comammox spatial distribution in natural environments such as surface fresh waters according to diurnal cycles, light attenuation coefficients, and the light penetration depths. Our findings therefore provide ecophysiological insights for further studies on comammox both in field and laboratory settings.
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Affiliation(s)
- Ekaterina Y. Gottshall
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States,*Correspondence: Ekaterina Y. Gottshall,
| | - Bruce Godfrey
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States
| | - Bo Li
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States
| | - Britt Abrahamson
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States
| | - Wei Qin
- Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, United States
| | - Mari Winkler
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States
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11
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Liu Z, Wei Q, Zou D, Zhang S, Zhang C, Quan Z, Li M. Deterministic Factors Determine the Comammox Community Composition in the Pearl River Estuary Ecosystem. Microbiol Spectr 2022;:e0101622. [PMID: 35913204 DOI: 10.1128/spectrum.01016-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Complete ammonia oxidizers (comammox) have been widely detected in riverine and estuarine ecosystems. However, knowledge about the process of comammox community assembly from freshwater to marine environments is still limited. Here, based on deep sequencing, we investigated the community composition of comammox along a salinity gradient in the Pearl River Estuary (PRE), South China. Our results showed that comammox microorganisms in the PRE sediments were extremely diverse and displayed distinct distributional patterns between upstream and downstream habitats. Quantitative PCR demonstrated that comammox was the dominant ammonia-oxidizing microorganism (AOM) in the PRE upstream sediments, and ammonia-oxidizing archaea (AOA) dominated the PRE downstream sediments, while ammonia-oxidizing bacteria (AOB) were not dominant in any section of the PRE. Neutral modeling revealed that stochastic processes explained a limited part of the variation in the comammox community. The majority of beta nearest-taxon index values were higher than 2, indicating that comammox community assembly in the PRE sediments was better explained through a deterministic process than through a stochastic process. Salinity and total nitrogen were the most important contributing factors that shaped the comammox community. This study expanded the current knowledge of the diversity and niche preference of comammox in the estuarine ecosystem, and further enhances our understanding of the assembly of comammox community from freshwater to marine environments. IMPORTANCE Microbial communities are shaped by stochastic (emigration, immigration, birth, death, and genetic drift of species) and deterministic (e.g., environmental factors) processes. However, it remains unknown as to which type of process is more important in influencing the comammox community assembly from freshwater to marine environments. In this study, we compared the relative importance of stochastic and deterministic processes in shaping the assembly of the comammox community, which demonstrated that the deterministic process was more important in determining the community assembly patterns in the PRE ecosystem.
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12
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Zhang SN, Wang JG, Wang DQ, Jiang QY, Quan ZX. Abundance and Niche Differentiation of Comammox in the Sludges of Wastewater Treatment Plants That Use the Anaerobic-Anoxic-Aerobic Process. Life (Basel) 2022; 12:life12070954. [PMID: 35888046 PMCID: PMC9322089 DOI: 10.3390/life12070954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/20/2022] [Accepted: 06/22/2022] [Indexed: 11/27/2022] Open
Abstract
Complete ammonia oxidizers (comammox), which directly oxidize ammonia to nitrate, were recently identified and found to be ubiquitous in artificial systems. Research on the abundance and niche differentiation of comammox in the sludges of wastewater treatment plants (WWTPs) would be useful for improving the nitrogen removal efficiency of WWTPs. Here, we investigated the relative abundance and diversity of comammox in fifteen sludges of five WWTPs that use the anaerobic−anoxic−aerobic process in Jinan, China, via quantitative polymerase chain reaction and high-throughput sequencing of the 16S rRNA gene and ammonia monooxygenase gene. In the activated sludges in the WWTPs, comammox clade A.1 was widely distributed and mostly comprised Candidatus Nitrospira nitrosa-like comammox (>98% of all comammox). The proportion of this clade was negatively correlated (p < 0.01) with the dissolved oxygen (DO) level (1.7−8 mg/L), and slight pH changes (7.20−7.70) affected the structure of the comammox populations. Nitrospira lineage I frequently coexisted with Nitrosomonas, which generally had a significant positive correlation (p < 0.05) with the DO level. Our study provided an insight into the structure of comammox and other nitrifier populations in WWTPs that use the anaerobic−anoxic−aerobic process, broadening the knowledge about the effects of DO on comammox and other nitrifiers.
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Affiliation(s)
| | | | | | - Qiu-Yue Jiang
- Correspondence: (Q.-Y.J.); (Z.-X.Q.); Tel.: +86-21-3124-0665 (Z.-X.Q.)
| | - Zhe-Xue Quan
- Correspondence: (Q.-Y.J.); (Z.-X.Q.); Tel.: +86-21-3124-0665 (Z.-X.Q.)
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13
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Abstract
Microbes commonly exist in diverse and complex communities where species interact, and their genomic repertoires evolve over time. Our understanding of species interaction and evolution has increased during the last decades, but most studies of evolutionary dynamics are based on single species in isolation or in experimental systems composed of few interacting species. Here, we use the microbial ecosystem found in groundwater-fed sand filter as a model to avoid this limitation. In these open systems, diverse microbial communities experience relatively stable conditions, and the coupling between chemical and biological processes is generally well defined. Metagenomic analysis of 12 sand filters communities revealed systematic co-occurrence of at least five comammox Nitrospira species, likely promoted by low ammonium concentrations. These Nitrospira species showed intrapopulation sequence diversity, although possible clonal expansion was detected in a few abundant local comammox populations. Nitrospira species showed low homologous recombination and strong purifying selection, the latter process being especially strong in genes essential in energy metabolism. Positive selection was detected for genes related to resistance to foreign DNA and phages. We found that, compared to other habitats, groundwater-fed sand filters impose strong purifying selection and low recombination on comammox Nitrospira populations. These results suggest that evolutionary processes are more affected by habitat type than by species identity. Together, this study improves our understanding of species interaction and evolution in complex microbial communities and sheds light on the environmental dependency of evolutionary processes. IMPORTANCE Microbial species interact with each other and their environment (ecological processes) and undergo changes in their genomic repertoire over time (evolutionary processes). How these two classes of processes interact is largely unknown, especially for complex communities, as most studies of microbial evolutionary dynamics consider single species in isolation or a few interacting species in simplified experimental systems. In this study, these limitations are circumvented by examining the microbial communities found in stable and well-described groundwater-fed sand filters. Combining metagenomics and strain-level analyses, we identified the microbial interactions and evolutionary processes affecting comammox Nitrospira, a recently discovered bacterial type capable of performing the whole nitrification process. We found that abundant and co-occurrent Nitrospira populations in groundwater-fed sand filters are characterized by low recombination and strong purifying selection. In addition, by comparing these observations with those obtained from Nitrospira species inhabiting other environments, we revealed that evolutionary processes are more affected by habitat type than by species identity.
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Affiliation(s)
- Alejandro Palomo
- Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Arnaud Dechesne
- Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Otto X. Cordero
- Ralph M. Parsons Laboratory for Environmental Science and Engineering, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Barth F. Smets
- Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark
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Baumann KBL, Thoma R, Callbeck CM, Niederdorfer R, Schubert CJ, Müller B, Lever MA, Bürgmann H. Microbial Nitrogen Transformation Potential in Sediments of Two Contrasting Lakes Is Spatially Structured but Seasonally Stable. mSphere 2022;:e0101321. [PMID: 35107340 DOI: 10.1128/msphere.01013-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The nitrogen (N) cycle is of global importance, as N is an essential element and a limiting nutrient in terrestrial and aquatic ecosystems. Excessive anthropogenic N fertilizer usage threatens sensitive downstream aquatic ecosystems. Although freshwater lake sediments remove N through various microbially mediated processes, few studies have investigated the microbial communities involved. In an integrated biogeochemical and microbiological study on a eutrophic and oligotrophic lake, we estimated N removal rates from pore water concentration gradients in sediments. Simultaneously, the abundance of different microbial N transformation genes was investigated using metagenomics on a seasonal and spatial scale. We observed that contrasting nutrient concentrations in sediments were associated with distinct microbial community compositions and significant differences in abundances of various N transformation genes. For both characteristics, we observed a more pronounced spatial than seasonal variability within each lake. The eutrophic Lake Baldegg showed a higher denitrification potential with higher nosZ gene (N2O reductase) abundances and higher nirS:nirK (nitrite reductase) ratios, indicating a greater capacity for complete denitrification. Correspondingly, this lake had a higher N removal efficiency. The oligotrophic Lake Sarnen, in contrast, had a higher potential for nitrification. Specifically, it harbored a high abundance of Nitrospira, including some with the potential for comammox. Our results demonstrate that knowledge of the genomic N transformation potential is important for interpreting N process rates and understanding how the lacustrine sedimentary N cycle responds to variations in trophic conditions. IMPORTANCE Anthropogenic nitrogen (N) inputs can lead to eutrophication in surface waters, especially in N-limited coastal ecosystems. Lakes effectively remove reactive N by transforming it to N2 through microbial denitrification or anammox. The rates and distributions of these microbial processes are affected by factors such as the amount and quality of settling organic material and nitrate concentrations. However, the microbial communities mediating these N transformation processes in freshwater lake sediments remain largely unknown. We provide the first seasonally and spatially resolved metagenomic analysis of the N cycle in sediments of two lakes with different trophic states. We show that lakes with different trophic states select for distinct communities of N-cycling microorganisms with contrasting functional potentials for N transformation.
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15
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Liu S, Jung MY, Zhang S, Wagner M, Daims H, Wanek W. Nitrogen Kinetic Isotope Effects of Nitrification by the Complete Ammonia Oxidizer Nitrospira inopinata. mSphere 2021; 6:e0063421. [PMID: 34878290 DOI: 10.1128/mSphere.00634-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Analysis of nitrogen isotope fractionation effects is useful for tracing biogeochemical nitrogen cycle processes. Nitrification can cause large nitrogen isotope effects through the enzymatic oxidation of ammonia (NH3) via nitrite (NO2−) to nitrate (NO3−) (15εNH4+→NO2- and 15εNO2-→NO3-). The isotope effects of ammonia-oxidizing bacteria (AOB) and archaea (AOA) and of nitrite-oxidizing bacteria (NOB) have been analyzed previously. Here, we studied the nitrogen isotope effects of the complete ammonia oxidizer (comammox) Nitrospira inopinata that oxidizes NH3 to NO3−. At high ammonium (NH4+) availability (1 mM) and pH between 6.5 and 8.5, its 15εNH4+→NO2- ranged from −33.1 to −27.1‰ based on substrate consumption (residual substrate isotopic composition) and −35.5 to −31.2‰ based on product formation (cumulative product isotopic composition), while the 15εNO2-→NO3- ranged from 6.5 to 11.1‰ based on substrate consumption. These values resemble isotope effects of AOB and AOA and of NOB in the genus Nitrospira, suggesting the absence of fundamental mechanistic differences between key enzymes for ammonia and nitrite oxidation in comammox and canonical nitrifiers. However, ambient pH and initial NH4+ concentrations influenced the isotope effects in N. inopinata. The 15εNH4+→NO2- based on product formation was smaller at pH 6.5 (−31.2‰) compared to pH 7.5 (−35.5‰) and pH 8.5 (−34.9‰), while 15εNO2-→NO3- was smaller at pH 8.5 (6.5‰) compared to pH 7.5 (8.8‰) and pH 6.5 (11.1‰). Isotopic fractionation via 15εNH4+→NO2- and 15εNO2-→NO3- was smaller at 0.1 mM NH4+ compared to 0.5 to 1.0 mM NH4+. Environmental factors, such as pH and NH4+ availability, therefore need to be considered when using isotope effects in 15N isotope fractionation models of nitrification. IMPORTANCE Nitrification is an important nitrogen cycle process in terrestrial and aquatic environments. The discovery of comammox has changed the view that canonical AOA, AOB, and NOB are the only chemolithoautotrophic organisms catalyzing nitrification. However, the contribution of comammox to nitrification in environmental and technical systems is far from being completely understood. This study revealed that, despite a phylogenetically distinct enzymatic repertoire for ammonia oxidation, nitrogen isotope effects of 15εNH4+→NO2- and 15εNO2-→NO3- in comammox do not differ significantly from those of canonical nitrifiers. Thus, nitrogen isotope effects are not suitable indicators to decipher the contribution of comammox to nitrification in environmental samples. Moreover, this is the first systematic study showing that the ambient pH and NH4+ concentration influence the isotope effects of nitrifiers. Hence, these key parameters should be considered in comparative analyses of isotope effects of nitrifiers across different growth conditions and environmental samples.
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16
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Sun D, Tang X, Zhao M, Zhang Z, Hou L, Liu M, Wang B, Klümper U, Han P. Corrigendum: Distribution and Diversity of Comammox Nitrospira in Coastal Wetlands of China. Front Microbiol 2021; 12:731921. [PMID: 34512610 PMCID: PMC8429277 DOI: 10.3389/fmicb.2021.731921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 07/31/2021] [Indexed: 11/19/2022] Open
Affiliation(s)
- Dongyao Sun
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai, China
| | - Xiufeng Tang
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai, China
| | - Mengyue Zhao
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai, China
| | - Zongxiao Zhang
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China
| | - Lijun Hou
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China
| | - Min Liu
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai, China.,Institute of Eco-Chongming, East China Normal University, Shanghai, China
| | - Baozhan Wang
- Key Laboratory of Microbiology for Agricultural Environment (Ministry of Agriculture), College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Uli Klümper
- Institute for Hydrobiology, Technische Universität Dresden, Dresden, Germany
| | - Ping Han
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai, China.,State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China.,Institute of Eco-Chongming, East China Normal University, Shanghai, China
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17
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Gao FY, Li YY, Yao HY. [Research progress on primers and molecular ecology of comammox Nitrospira]. Ying Yong Sheng Tai Xue Bao 2021; 31:2831-2840. [PMID: 34494806 DOI: 10.13287/j.1001-9332.202008.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Nitrification is a key process in nitrogen cycling, which has received considerable attention in the research field of soil biochemistry. In 2015, the discovery of complete ammonia oxidizers (Comammox) challenged conventional two-step nitrification perspective, which represented a paradigm shift in the understanding of soil nitrogen cycling. Comammox are a group of microorganisms capable of conducting both steps of nitrification. In this review, we summarized current understan-ding of the molecular ecology of comammox, including specific molecular biomarkers for comammox, phylogenetic and genomic surveys of comammox and particularly the distribution, diversity and ecological significance of comammox in soil. Further studies should focus on: 1) designing specific molecular biomarkers to examine the distribution and diversity of comammox; 2) optimizing cultivation techniques to isolate/enrich comammox cultures and expending our insights into physiological traits of comammox; 3) characterizing their distribution and in situ activities to elucidate the contribution of comammox processes to soil nitrification and their ecological features, which may assist in unco-vering the mechanisms of nitrogen cycling and promote the environmental protection of soil ecosystem.
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Affiliation(s)
- Fu-Yun Gao
- Wuhan Institute of Technology, Wuhan 430205, China.,Institite of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, Fujian, China
| | - Ya-Ying Li
- Wuhan Institute of Technology, Wuhan 430205, China.,Institite of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, Fujian, China
| | - Huai-Ying Yao
- Wuhan Institute of Technology, Wuhan 430205, China.,Institite of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, Fujian, China
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Rodriguez J, Chakrabarti S, Choi E, Shehadeh N, Sierra-Martinez S, Zhao J, Martens-Habbena W. Nutrient-Limited Enrichments of Nitrifiers From Soil Yield Consortia of Nitrosocosmicus-Affiliated AOA and Nitrospira-Affiliated NOB. Front Microbiol 2021; 12:671480. [PMID: 34322099 PMCID: PMC8312096 DOI: 10.3389/fmicb.2021.671480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 06/22/2021] [Indexed: 11/21/2022] Open
Abstract
The discovery of ammonia-oxidizing archaea (AOA) and complete ammonia-oxidizing (comammox) bacteria widespread in terrestrial ecosystems indicates an important role of these organisms in terrestrial nitrification. Recent evidence indicated a higher ammonia affinity of comammox bacteria than of terrestrial AOA and ammonia-oxidizing bacteria (AOB), suggesting that comammox bacteria could potentially represent the most low-nutrient adapted nitrifiers in terrestrial systems. We hypothesized that a nutrient-limited enrichment strategy could exploit the differences in cellular kinetic properties and yield enrichments dominated by high affinity and high yield comammox bacteria. Using soil with a mixed community of AOA, AOB, and comammox Nitrospira, we compared performance of nutrient-limited chemostat enrichment with or without batch culture pre-enrichment in two different growth media without inhibitors or antibiotics. Monitoring of microbial community composition via 16S rRNA and amoA gene sequencing showed that batch enrichments were dominated by AOB, accompanied by low numbers of AOA and comammox Nitrospira. In contrast, nutrient-limited enrichment directly from soil, and nutrient-limited sub-cultivation of batch enrichments consistently yielded high enrichments of Nitrosocosmicus-affiliated AOA associated with multiple canonical nitrite-oxidizing Nitrospira strains, whereas AOB numbers dropped below 0.1% and comammox Nitrospira were lost completely. Our results reveal competitiveness of Nitrosocosmicus sp. under nutrient limitation, and a likely more complex or demanding ecological niche of soil comammox Nitrospira than simulated in our nutrient-limited chemostat experiments.
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Affiliation(s)
| | | | | | | | | | | | - Willm Martens-Habbena
- Fort Lauderdale Research and Education Center, Department of Microbiology and Cell Science, University of Florida, Davie, FL, United States
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19
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Sato Y, Tanaka E, Hori T, Futamata H, Murofushi K, Takagi H, Akachi T, Miwa T, Inaba T, Aoyagi T, Habe H. Efficient conversion of organic nitrogenous wastewater to nitrate solution driven by comammox Nitrospira. Water Res 2021; 197:117088. [PMID: 33813172 DOI: 10.1016/j.watres.2021.117088] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 03/17/2021] [Accepted: 03/23/2021] [Indexed: 06/12/2023]
Abstract
A bacterium capable of complete ammonia oxidation (comammox) has been widely found in various environments, whereas its industrial application is limited due to the difficulty of cultivation and/or enrichment. We developed a biological system to produce a high-quality nitrate solution for use in hydroponic fertilizer. The system was composed of two separate reactors for ammonification and nitrification and was found to have a stable and efficient performance in the conversion of organic nitrogen to nitrate. To determine the key microbes involved and better understand the system, the microbial communities in the reactors were analyzed by 16S rRNA gene sequencing in combination with a shotgun metagenomic analysis. Canonical ammonia-oxidizing bacteria, which can only catalyze the oxidation of ammonia to nitrite, were detected with negligible relative abundances, while a comammox Nitrospira-related operational taxonomic unit (OTU) dominated the nitrification reactor. Furthermore, the comammox-type ammonia monooxygenase was found to be 500 times more highly expressed than the canonical one by quantitative PCR, indicating that comammox was the main driver of the stable and efficient ammonia oxidation in the system. A microbial co-occurrence analysis revealed a strong positive correlation between Nitrospira and several OTUs, some of which, such as Anaerolinea OTU, have been found to co-exist with comammox Nitrospira in the biofilms of water treatment systems. Given that these OTUs were abundant only on microbe-attached carriers in the system, their co-existence within the biofilm could be beneficial to stabilize the Nitrospira abundance, possibly by physically preventing oxygen exposure as well as cell spillage.
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Affiliation(s)
- Yuya Sato
- Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
| | - Eiji Tanaka
- Department of Eco Farm, IAI Corporation, 577-1 Obane, Shimizu, Shizuoka 424-0103, Japan
| | - Tomoyuki Hori
- Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Hiroyuki Futamata
- Research Institution of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, Shizuoka 422-8529, Japan; Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8011, Japan
| | - Keita Murofushi
- Department of Environment and Energy, Industrial Research Institute of Shizuoka Prefecture, 2078 Makigaya, Aoi-ku, Shizuoka, Shizuoka 421-1298, Japan
| | - Hiroshi Takagi
- Numazu Technical Support Center, Industrial Research Institute of Shizuoka Prefecture, 3981-1 Ohoka, Numazu, Shizuoka 410-0022, Japan
| | - Takuto Akachi
- Department of Eco Farm, IAI Corporation, 577-1 Obane, Shimizu, Shizuoka 424-0103, Japan
| | - Teruhiko Miwa
- Department of Eco Farm, IAI Corporation, 577-1 Obane, Shimizu, Shizuoka 424-0103, Japan
| | - Tomohiro Inaba
- Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Tomo Aoyagi
- Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Hiroshi Habe
- Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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Liu G, Wu X, Li D, Jiang L, Huang J, Zhuang L. Long-Term Low Dissolved Oxygen Operation Decreases N 2O Emissions in the Activated Sludge Process. Environ Sci Technol 2021; 55:6975-6983. [PMID: 33904707 DOI: 10.1021/acs.est.0c07279] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nitrous oxide (N2O) is an important greenhouse gas and a dominant ozone-depleting substance. Nitrification in the activated sludge process (ASP) is an important N2O emission source. This study demonstrated that a short-term low dissolved oxygen (DO) increased the N2O emissions by six times, while long-term low DO operation decreased the N2O emissions by 54% (P < 0.01). Under long-term low DO, the ammonia oxidizer abundance in the ASP increased significantly, and thus, complete nitrification was recovered and no NH3 or nitrite accumulated. Moreover, long-term low DO decreased the abundance of ammonia-oxidizing bacteria (AOB) by 28%, while increased the abundance of ammonia-oxidizing archaea (AOA) by 507%, mainly due to their higher oxygen affinity. As a result, AOA outnumbered AOB with the AOA/AOB amoA gene ratio increasing to 19.5 under long-term low DO. The efficient nitrification and decreased AOB abundance might not increase N2O production via AOB under long-term low DO conditions. The enriched AOA could decrease the N2O emissions because they were reported to lack canonical nitric oxide (NO) reductase genes that convert NO to N2O. Probably because of AOA enrichment, the positive and significant (P = 0.02) correlation of N2O emission and nitrite concentration became insignificant (P = 0.332) after 80 days of low DO operation. Therefore, ASPs can be operated with low DO and extended sludge age to synchronously reduce N2O production and carbon dioxide emissions owing to lower aeration energy without compromising the nitrification efficiency.
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Affiliation(s)
- Guoqiang Liu
- School of Environment, Guangdong Engineering Research Center of Water Treatment Processes and Materials and Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China
| | - Xianwei Wu
- School of Environment, Guangdong Engineering Research Center of Water Treatment Processes and Materials and Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China
| | - Deyong Li
- School of Environment, Guangdong Engineering Research Center of Water Treatment Processes and Materials and Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China
| | - Lugao Jiang
- School of Environment, Guangdong Engineering Research Center of Water Treatment Processes and Materials and Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China
| | - Ju Huang
- School of Environment, Guangdong Engineering Research Center of Water Treatment Processes and Materials and Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China
| | - Li Zhuang
- School of Environment, Guangdong Engineering Research Center of Water Treatment Processes and Materials and Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China
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21
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Zhou LJ, Han P, Zhao M, Yu Y, Sun D, Hou L, Liu M, Zhao Q, Tang X, Klümper U, Gu JD, Men Y, Wu QL. Biotransformation of lincomycin and fluoroquinolone antibiotics by the ammonia oxidizers AOA, AOB and comammox: A comparison of removal, pathways, and mechanisms. Water Res 2021; 196:117003. [PMID: 33730544 DOI: 10.1016/j.watres.2021.117003] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/01/2021] [Accepted: 03/02/2021] [Indexed: 06/12/2023]
Abstract
In this study, we evaluated the biotransformation mechanisms of lincomycin (LIN) and three fluoroquinolone antibiotics (FQs), ciprofloxacin (CFX), norfloxacin (NFX), and ofloxacin (OFX), which regularly enter aquatic environments through human activities, by different ammonia-oxidizing microorganisms (AOM). The organisms included a pure culture of the complete ammonia oxidizer (comammox) Nitrospira inopinata, an ammonia oxidizing archaeon (AOA) Nitrososphaera gargensis, and an ammonia-oxidizing bacterium (AOB) Nitrosomonas nitrosa Nm90. The removal of these antibiotics by the pure microbial cultures and the protein-normalized biotransformation rate constants indicated that LIN was significantly co-metabolically biotransformed by AOA and comammox, but not by AOB. CFX and NFX were significantly co-metabolized by AOA and AOB, but not by comammox. None of the tested cultures transformed OFX effectively. Generally, AOA showed the best biotransformation capability for LIN and FQs, followed by comammox and AOB. The transformation products and their related biotransformation mechanisms were also elucidated. i) The AOA performed hydroxylation, S-oxidation, and demethylation of LIN, as well as nitrosation and cleavage of the piperazine moiety of CFX and NFX; ii) the AOB utilized nitrosation to biotransform CFX and NFX; and iii) the comammox carried out hydroxylation, demethylation, and demethylthioation of LIN. Hydroxylamine, an intermediate of ammonia oxidation, chemically reacted with LIN and the selected FQs, with removals exceeding 90%. Collectively, these findings provide important fundamental insights into the roles of different ammonia oxidizers and their intermediates on LIN and FQ biotransformation in nitrifying environments including wastewater treatment systems.
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Affiliation(s)
- Li-Jun Zhou
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Ping Han
- School of Geographic Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China; State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China; Institute of Eco-Chongming, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China.
| | - Mengyue Zhao
- School of Geographic Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China
| | - Yaochun Yu
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States; Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Dongyao Sun
- School of Geographic Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China
| | - Lijun Hou
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China
| | - Min Liu
- School of Geographic Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China; Institute of Eco-Chongming, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China
| | - Qiang Zhao
- School of Geographic Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China
| | - Xiufeng Tang
- School of Geographic Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China
| | - Uli Klümper
- Institute for Hydrobiology, Technische Universität Dresden, Dresden 01217, Germany
| | - Ji-Dong Gu
- Environmental Engineering, Guangdong Technion - Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong 515063, China
| | - Yujie Men
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States; Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Qinglong L Wu
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; Sino-Danish Center for Science and Education, University of Chinese Academy of Sciences, Beijing, China
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22
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Li D, Fang F, Liu G. Efficient Nitrification and Low-Level N 2O Emission in a Weakly Acidic Bioreactor at Low Dissolved-Oxygen Levels Are Due to Comammox. Appl Environ Microbiol 2021; 87:e00154-21. [PMID: 33975896 PMCID: PMC8208134 DOI: 10.1128/aem.00154-21r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 03/13/2021] [Indexed: 01/31/2023] Open
Abstract
Nitrification is an essential process for nutrient removal from wastewater and an important emission source of nitrous oxide (N2O), which is a powerful greenhouse gas and a dominant ozone-depleting substance. In this study, nitrification and N2O emissions were tested in two weakly acidic (pH 6.3 to 6.8) reactors: one with dissolved oxygen (DO) at over 2.0 mg/liter and the other with DO at approximately 0.5 mg/liter. Efficient nitrification was achieved in both reactors. Compared to that in the high-DO reactor, N2O emission in the low-DO reactor decreased slightly, by 20%, and had insignificant correlation with the fluctuations of DO (P = 0.935) and nitrite (P = 0.713), indicating that N2O might not be produced mainly via nitrifier denitrification. Based on quantitative PCR (qPCR), quantitative fluorescent in situ hybridization (qFISH), and functional gene amplicon and metagenome sequencing, it was found that complete ammonia oxidizers (comammox), i.e., Nitrospira organisms, significantly outnumbered canonical ammonia-oxidizing bacteria (AOB) in both weakly acidic reactors, especially in the low-DO reactor with the comammox/AOB amoA gene ratio increasing from 6.6 to 17.1. Therefore, it was speculated that the enriched comammox was the primary cause for the slightly decreased N2O emission under long-term low DO in the weakly acidic reactor. This study demonstrated that the comammox Nitrospira can survive well under the weakly acidic and low-DO conditions, implying that achieving efficient nitrification with low N2O emission as well as low energy and alkalinity consumption is feasible for wastewater treatment.IMPORTANCE Nitrification in wastewater treatment is an important process for eutrophication control and an emission source for the greenhouse gas N2O. The nitrifying process is usually operated at a slightly alkaline pH and high DO (>2 mg/liter) to ensure efficient nitrification. However, it consumes a large amount of energy and chemicals, especially for wastewater without sufficient alkalinity. This paper demonstrates that comammox can adapt well to the weakly acidic and low-DO bioreactors, with a result of efficient nitrification and low N2O emission. These findings indicate that comammox organisms are significant for sustainable wastewater treatment, which provides an opportunity to achieve efficient nitrification with low N2O production as well as low energy and chemical consumption simultaneously.
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Affiliation(s)
- Deyong Li
- School of the Environment, Guangdong Engineering Research Center of Water Treatment Processes and Materials, Jinan University, Guangzhou, China
- School of the Environment, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou, China
| | - Fang Fang
- College of the Environment and Ecology, Chongqing University, Chongqing, China
| | - Guoqiang Liu
- School of the Environment, Guangdong Engineering Research Center of Water Treatment Processes and Materials, Jinan University, Guangzhou, China
- School of the Environment, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou, China
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23
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Fujitani H, Nomachi M, Takahashi Y, Hasebe Y, Eguchi M, Tsuneda S. Successful enrichment of low-abundant comammox Nitrospira from nitrifying granules under ammonia-limited conditions. FEMS Microbiol Lett 2021; 367:5731803. [PMID: 32037440 DOI: 10.1093/femsle/fnaa025] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 02/08/2020] [Indexed: 12/25/2022] Open
Abstract
In artificial engineered systems, nitrification is a key reaction that accounts for the removal of biological nitrogen. Recently, a single microbe capable of oxidizing ammonia to nitrate, known as a complete ammonia oxidizer (comammox), has been discovered. Although the abundance and diversity of comammox Nitrospira in engineered systems have been identified through molecular-based approaches, the enrichment and isolation of comammox Nitrospira remains a challenge. Therefore, the aim of this study was to enrich comammox Nitrospira from nitrifying granules, which were used to increase the efficiency of biological nitrogen removal in wastewater treatment plants. We sought to accomplish this through the use of a fixed-bed continuous feeding bioreactor. Fluorescence in situ hybridization, 16S rRNA gene amplicon sequencing and qPCR of functional genes were utilized to monitor the growth of nitrifiers including comammox Nitrospira. Cloning of comammox amoA genes identified amoA phylogeny of enriched comammox Nitrospira. This work is an example demonstrating that continuous supply of low ammonium concentrations alongside biomass carriers is effective in cultivating comammox Nitrospira from engineered systems.
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Affiliation(s)
- Hirotsugu Fujitani
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Central 6, Higashi 1-1-1, Tsukuba, 305-8566, Japan.,Research Organization for Nano & Life Innovation, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan
| | - Manami Nomachi
- Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan
| | - Yu Takahashi
- Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan
| | - Yoshiaki Hasebe
- Organo Corp. R&D Center, Nishioonuma 4-4-1, Minami-ku, Sagamihara, 252-0332, Japan
| | - Masahiro Eguchi
- Organo Corp. R&D Center, Nishioonuma 4-4-1, Minami-ku, Sagamihara, 252-0332, Japan
| | - Satoshi Tsuneda
- Research Organization for Nano & Life Innovation, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan.,Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan
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24
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Vijayan A, Vattiringal Jayadradhan RK, Pillai D, Prasannan Geetha P, Joseph V, Isaac Sarojini BS. Nitrospira as versatile nitrifiers: Taxonomy, ecophysiology, genome characteristics, growth, and metabolic diversity. J Basic Microbiol 2021; 61:88-109. [PMID: 33448079 DOI: 10.1002/jobm.202000485] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 11/30/2020] [Accepted: 12/28/2020] [Indexed: 12/14/2022]
Abstract
The global nitrogen cycle is of paramount significance as it affects important processes like primary productivity and decomposition. Nitrification, the oxidation of ammonia to nitrate via nitrite, is a key process in the nitrogen cycle. The knowledge about nitrification has been challenged during the last few decades with inventions like anaerobic ammonia oxidation, ammonia-oxidizing archaea, and recently the complete ammonia oxidation (comammox). The discovery of comammox Nitrospira has made a paradigm shift in nitrification, before which it was considered as a two-step process, mediated by chemolithoautotrophic ammonia oxidizers and nitrite oxidizers. The genome of comammox Nitrospira equipped with molecular machineries for both ammonia and nitrite oxidation. The genus Nitrospira is ubiquitous, comes under phylum Nitrospirae, which comprises six sublineages consisting of canonical nitrite oxidizers and comammox. The single-step nitrification is energetically more feasible; furthermore, the existence of diverse metabolic pathways in Nitrospira is critical for its establishment in various habitats. The present review discusses the taxonomy, ecophysiology, isolation, identification, growth, and metabolic diversity of the genus Nitrospira; compares the genomes of canonical nitrite-oxidizing Nitrospira and comammox Nitrospira, and analyses the differences of Nitrospira with other nitrifying bacteria.
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Affiliation(s)
- Ardhra Vijayan
- Department of Aquatic Animal Health Management, Kerala University of Fisheries and Ocean Studies, Kochi, Kerala, India
| | - Rejish Kumar Vattiringal Jayadradhan
- Department of Aquatic Animal Health Management, Kerala University of Fisheries and Ocean Studies, Kochi, Kerala, India.,Department of Aquaculture, Kerala University of Fisheries and Ocean Studies, Kochi, Kerala, India
| | - Devika Pillai
- Department of Aquatic Animal Health Management, Kerala University of Fisheries and Ocean Studies, Kochi, Kerala, India
| | - Preena Prasannan Geetha
- National Centre for Aquatic Animal Health, Cochin University of Science and Technology, Kochi, Kerala, India
| | - Valsamma Joseph
- National Centre for Aquatic Animal Health, Cochin University of Science and Technology, Kochi, Kerala, India
| | - Bright Singh Isaac Sarojini
- National Centre for Aquatic Animal Health, Cochin University of Science and Technology, Kochi, Kerala, India
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25
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Sun D, Tang X, Zhao M, Zhang Z, Hou L, Liu M, Wang B, Klümper U, Han P. Distribution and Diversity of Comammox Nitrospira in Coastal Wetlands of China. Front Microbiol 2020; 11:589268. [PMID: 33123118 PMCID: PMC7573150 DOI: 10.3389/fmicb.2020.589268] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/15/2020] [Indexed: 12/17/2022] Open
Abstract
Complete ammonia oxidizers (comammox), able to individually oxidize ammonia to nitrate, are considered to play a significant role in the global nitrogen cycle. However, the distribution of comammox Nitrospira in estuarine tidal flat wetland and the environmental drivers affecting their abundance and diversity remain unknown. Here, we present a large-scale investigation on the geographical distribution of comammox Nitrospira along the estuarine tidal flat wetlands of China, where comammox Nitrospira were successfully detected in 9 of the 16 sampling sites. The abundance of comammox Nitrospira ranged from 4.15 × 105 to 6.67 × 106 copies/g, 2.21- to 5.44-folds lower than canonical ammonia oxidizers: ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). Phylogenetic analysis based on the alpha subunit of the ammonia monooxygenase encoding gene (amoA) revealed that comammox Nitrospira Clade A, mainly originating from upstream river inputs, accounts for more than 80% of the detected comammox Nitrospira, whereas comammox Nitrospira clade B were rarely detected. Comammox Nitrospira abundance and dominant comammox Nitrospira OTUs varied within the estuarine samples, showing a geographical pattern. Salinity and pH were the most important environmental drivers affecting the distribution of comammox Nitrospira in estuarine tidal flat wetlands. The abundance of comammox Nitrospira was further negatively correlated with high ammonia and nitrite concentrations. Altogether, this study revealed the existence, abundance and distribution of comammox Nitrospira and the driving environmental factors in estuarine ecosystems, thus providing insights into the ecological niches of this recently discovered nitrifying consortium and their contributions to nitrification in global estuarine environments.
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Affiliation(s)
- Dongyao Sun
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai, China
| | - Xiufeng Tang
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai, China
| | - Mengyue Zhao
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai, China
| | - Zongxiao Zhang
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China
| | - Lijun Hou
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China
| | - Min Liu
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai, China.,Institute of Eco-Chongming, East China Normal University, Shanghai, China
| | - Baozhan Wang
- Key Laboratory of Microbiology for Agricultural Environment (Ministry of Agriculture), College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Uli Klümper
- Institute for Hydrobiology, Technische Universität Dresden, Dresden, Germany
| | - Ping Han
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai, China.,State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China.,Institute of Eco-Chongming, East China Normal University, Shanghai, China
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26
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Jiang R, Wang JG, Zhu T, Zou B, Wang DQ, Rhee SK, An D, Ji ZY, Quan ZX. Use of Newly Designed Primers for Quantification of Complete Ammonia-Oxidizing ( Comammox) Bacterial Clades and Strict Nitrite Oxidizers in the Genus Nitrospira. Appl Environ Microbiol 2020; 86:e01775-20. [PMID: 32826214 PMCID: PMC7531962 DOI: 10.1128/aem.01775-20] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 08/08/2020] [Indexed: 02/01/2023] Open
Abstract
Complete ammonia-oxidizing (comammox) bacteria play key roles in environmental nitrogen cycling and all belong to the genus Nitrospira, which was originally believed to include only strict nitrite-oxidizing bacteria (sNOB). Thus, differential estimation of sNOB abundance from that of comammox Nitrospira has become problematic, since both contain nitrite oxidoreductase genes that serve as common targets for sNOB detection. Herein, we developed novel comammox Nitrospira clade A- and B-specific primer sets targeting the α-subunit of the ammonia monooxygenase gene (amoA) and a sNOB-specific primer set targeting the cyanase gene (cynS) for quantitative PCR (qPCR). The high coverage and specificity of these primers were checked by use of metagenome and metatranscriptome data sets. Efficient and specific amplification with these primers was demonstrated using various environmental samples. Using the newly designed primers, we successfully estimated the abundances of comammox Nitrospira and sNOB in samples from two chloramination-treated drinking water systems and found that, in most samples, comammox Nitrospira clade A was the dominant type of Nitrospira and also served as the primary ammonia oxidizer. Compared with other ammonia oxidizers, comammox Nitrospira had a higher abundance in process water samples in these two drinking water systems. We also demonstrated that sNOB can be readily misrepresented by an earlier method, calculated by subtracting the comammox Nitrospira abundance from the total Nitrospira abundance, especially when the comammox Nitrospira proportion is relatively high. The new primer sets were successfully applied to comammox Nitrospira and sNOB quantification, which may prove useful in understanding the roles of Nitrospira in nitrification in various ecosystems.IMPORTANCENitrospira is a dominant nitrite-oxidizing bacterium in many artificial and natural environments. The discovery of complete ammonia oxidizers in the genus Nitrospira prevents the use of previously identified primers targeting the Nitrospira 16S rRNA gene or nitrite oxidoreductase (nxr) gene for differential determination of strict nitrite-oxidizing bacteria (sNOB) in the genus Nitrospira and among comammox bacteria in this genus. We designed three novel primer sets that enabled quantification of comammox Nitrospira clades A and B and sNOB with high coverage, specificity, and accuracy in various environments. With the designed primer sets, sNOB and comammox Nitrospira were differentially estimated in drinking water systems, and we found that comammox clade A predominated over sNOB and other ammonia oxidizers in process water samples. Accurate quantification of comammox Nitrospira and sNOB by use of the newly designed primers will provide essential information for evaluating the contribution of Nitrospira to nitrification in various ecosystems.
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Affiliation(s)
- Ran Jiang
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Jian-Gong Wang
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Ting Zhu
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Bin Zou
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Dan-Qi Wang
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Sung-Keun Rhee
- Department of Microbiology, Chungbuk National University, Cheongju, Republic of Korea
| | - Dong An
- Department of Environmental Science and Engineering, Fudan University, Shanghai, China
| | - Zhi-Yuan Ji
- Hangzhou Water Holding Group Co., Ltd., Hangzhou, China
| | - Zhe-Xue Quan
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
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27
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Lin C, Xu H, Qin W, Xu S, Tang X, Kuang L, Wang X, Jiang B, Chen J, Shan J, Adams J, Qin H, Wang B. Evaluation of Two Primer Sets for Amplification of Comammox Nitrospira amoA Genes in Wetland Soils. Front Microbiol 2020; 11:560942. [PMID: 33101233 PMCID: PMC7555835 DOI: 10.3389/fmicb.2020.560942] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 09/10/2020] [Indexed: 01/23/2023] Open
Abstract
After the discovery of complete ammonia-oxidizing (comammox) Nitrospira, detection and assessments of the contribution of comammox Nitrospira communities to nitrogen cycling are in great demand. PCR-based approach, a common method for the detection of comammox, depends strongly on accurate amplification of the amoA genes from the original DNA samples using appropriate primers. In this study, we reported an evaluation of the performance of two commonly used primer sets, Ntsp-amoA 162F/359R and comaA/B-244f/659r, for amplifying the comammox amoA genes from three representative wetland soils in China [Sangsang (SS), Sanjiang (SJ), and Xianghai (XH)]. Our results demonstrated the two primer sets could both successfully amplify the clades with high relative abundances (RA), and further revealed a broadly similar diversity and community composition of dominant comammox operational taxonomic units (OTUs) (RA ≥ 1%) in each of the three wetland soils. However, the clades with low RA, such as the clade A (1.26%) in SJ and the clade B (11.54%) in XH that were recovered by metagenomics analysis, failed to be amplified using comaA/B-244f/659r, but were successfully amplified and sequenced using Ntsp-amoA 162F/359R. It indicated that, compared to comaA/B-244f/659r, Ntsp-amoA 162F/359R was more sensitive to the clades with low RA. However, it is worth noting that Ntsp-amoA 162F/359R would overestimate the RA of some rare clades. For example, the RAs of clade B in XH were overestimated by 32-fold. Furthermore, high levels of non-target amplification were detected via gel electrophoresis using both primer sets, especially for comammox Clade B amoA genes, implying that we should treat qPCR results based on these primers with caution. Taken together, our study comprehensively compared the performance of the two primer sets on the sensitivity and specificity of amplifying comammox amoA genes in three wetland soils, pointing out the necessity of further development of new primers for the efficient and accurate detection of comammox in various environments.
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Affiliation(s)
- Chenshuo Lin
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China.,Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing, China
| | - Hang Xu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing, China
| | - Wei Qin
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, United States
| | - Shaoyi Xu
- Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental Resource Sciences, Zhejiang University, Hangzhou, China
| | - Xiufeng Tang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Lu Kuang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Xinxin Wang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Bin Jiang
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Junhui Chen
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China
| | - Jun Shan
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Jonathan Adams
- School of Geography and Ocean Science, Nanjing University, Nanjing, China
| | - Hua Qin
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China
| | - Baozhan Wang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.,Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
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28
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Fujitani H, Momiuchi K, Ishii K, Nomachi M, Kikuchi S, Ushiki N, Sekiguchi Y, Tsuneda S. Genomic and Physiological Characteristics of a Novel Nitrite-Oxidizing Nitrospira Strain Isolated From a Drinking Water Treatment Plant. Front Microbiol 2020; 11:545190. [PMID: 33042056 PMCID: PMC7522533 DOI: 10.3389/fmicb.2020.545190] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 08/24/2020] [Indexed: 11/13/2022] Open
Abstract
Nitrite-oxidizing bacteria (NOB) catalyze the second step of nitrification, which is an important process of the biogeochemical nitrogen cycle and is exploited extensively as a biological nitrogen removal process. Members of the genus Nitrospira are often identified as the dominant NOB in a diverse range of natural and artificial environments. Additionally, a number of studies examining the distribution, abundance, and characterization of complete ammonia oxidation (comammox) Nitrospira support the ecological importance of the genus Nitrospira. However, niche differentiation between nitrite-oxidizing Nitrospira and comammox Nitrospira remains unknown due to a lack of pure cultures. In this study, we report the isolation, physiology, and genome of a novel nitrite-oxidizing Nitrospira strain isolated from a fixed-bed column at a drinking water treatment plant. Continuous feeding of ammonia led to the enrichment of Nitrospira-like cells, as well as members of ammonia-oxidizing genus Nitrosomonas. Subsequently, a microcolony sorting technique was used to isolate a novel nitrite-oxidizing Nitrospira strain. Sequences of strains showing the growth of microcolonies in microtiter plates were checked. Consequently, the most abundant operational taxonomic unit (OTU) exhibited high sequence similarity with Nitrospira japonica (98%) at the 16S rRNA gene level. The two other Nitrospira OTUs shared over 99% sequence similarities with N. japonica and Nitrospira sp. strain GC86. Only one strain identified as Nitrospira was successfully subcultivated and designated as Nitrospira sp. strain KM1 with high sequence similarity with N. japonica (98%). The half saturation constant for nitrite and the maximum nitrite oxidation rate of strain KM1 were orders of magnitude lower than the published data of other known Nitrospira strains; moreover, strain KM1 was more sensitive to free ammonia compared with previously isolated Nitrospira strains. Therefore, the new Nitrospira strain appears to be better adapted to oligotrophic environments compared with other known non-marine nitrite oxidizers. The complete genome of strain KM1 was 4,509,223 bp in length and contained 4,318 predicted coding sequences. Average nucleotide identities between strain KM1 and known cultured Nitrospira genome sequences are 76.7-78.4%, suggesting at least species-level novelty of the strain in the Nitrospira lineage II. These findings broaden knowledge of the ecophysiological diversity of nitrite-oxidizing Nitrospira.
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Affiliation(s)
- Hirotsugu Fujitani
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.,Research Organization for Nano & Life Innovation, Waseda University, Tokyo, Japan
| | - Kengo Momiuchi
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Kento Ishii
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Manami Nomachi
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Shuta Kikuchi
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Norisuke Ushiki
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Yuji Sekiguchi
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - Satoshi Tsuneda
- Research Organization for Nano & Life Innovation, Waseda University, Tokyo, Japan.,Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
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Abstract
It has been almost 150 years since Jean-Jacques Schloesing and Achille Müntz discovered that the process of nitrification, the oxidation of ammonium to nitrate, is a biological process carried out by microorganisms. In the following 15 years, numerous researchers independently contributed paradigm shifting discoveries that formed the foundation of nitrification and nitrification-related research. One of them was Sergei Winogradsky, whose major accomplishments include the discovery of both lithotrophy (in sulfur-oxidizing bacteria) and chemoautotrophy (in nitrifying bacteria). However, Winogradsky often receives most of the credit for many other foundational nitrification discoveries made by his contemporaries. This accumulation of credit over time is at least in part due to the increased attention, Winogradsky receives in the scientific literature and textbooks as a "founder of microbiology" and "the founder of microbial ecology." Here, some light is shed on several other researchers who are often overlooked, but whose work was instrumental to the emerging field of nitrification and to the work of Winogradsky himself. Specifically, the discovery of the biological process of nitrification by Schloesing and Müntz, the isolation of the first nitrifier by Grace and Percy Frankland, and the observation that nitrification is carried out by two distinct groups of microorganisms by Robert Warington are highlighted. Finally, the more recent discoveries of the chemolithoautotrophic ammonia-oxidizing archaea and complete ammonia oxidizers are put into this historical context.
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Affiliation(s)
- Christopher J. Sedlacek
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
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Takahashi Y, Fujitani H, Hirono Y, Tago K, Wang Y, Hayatsu M, Tsuneda S. Enrichment of Comammox and Nitrite-Oxidizing Nitrospira From Acidic Soils. Front Microbiol 2020; 11:1737. [PMID: 32849373 PMCID: PMC7396549 DOI: 10.3389/fmicb.2020.01737] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 07/02/2020] [Indexed: 12/02/2022] Open
Abstract
In agricultural soils fertilized with a high amount of ammonium nitrogen, the pH decreases because of the oxidation of ammonia by nitrifiers. Molecular-based analyses have revealed that members of the genus Nitrospira dominate over other nitrifiers in some acidic soils. However, terrestrial Nitrospira are rarely cultivated and little is known about their ecophysiology. In addition, recent studies discovered a single microbe with the potential to oxidize both ammonia and nitrite (complete ammonia oxidizer; comammox) within Nitrospira, which had been previously recognized as a nitrite oxidizer. Despite their broad distribution, there are no enrichment samples of comammox from terrestrial or acidic environments. Here, we report the selective enrichment of both comammox and nitrite-oxidizing Nitrospira from the acidic soil of a heavily fertilized tea field. Long-term enrichment was performed with two individual continuous-feeding bioreactors capable of controlling ammonia or nitrite concentration and pH. We found that excessive ammonium supply was a key factor to enhance the growth of comammox Nitrospira under acidic conditions. Additionally, a low concentration of nitrite was fed to prevent the accumulation of free nitrous acid and inhibition of cell growth under low pH, resulting in the selective enrichment of nitrite-oxidizing Nitrospira. Based on 16S rRNA gene analysis, Nitrospira accounting for only 1.2% in an initial soil increased to approximately 80% of the total microorganisms in both ammonia- and nitrite-fed bioreactors. Furthermore, amoA amplicon sequencing revealed that two phylotypes belonging to comammox clade A were enriched in an ammonia-fed bioreactor. One group was closely related to previously cultivated strains, and the other was classified into a different cluster consisting of only uncultivated representatives. These two groups coexisted in the bioreactor controlled at pH 6.0, but the latter became dominant after the pH decreased to 5.5. Additionally, a physiological experiment revealed that the enrichment sample oxidizes ammonia at pH <4, which is in accordance with the strongly acidic tea field soil; this value is lower than the active pH range of isolated acid-adapted nitrifiers. In conclusion, we successfully enriched multiple phylotypes of comammox and nitrite-oxidizing Nitrospira and revealed that the pH and concentrations of protonated N-compounds were potential niche determinants.
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Affiliation(s)
- Yu Takahashi
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Hirotsugu Fujitani
- Department of Biological Sciences, Faculty of Science and Engineering, Chuo University, Tokyo, Japan
| | - Yuhei Hirono
- Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization (NARO), Shimada, Japan
| | - Kanako Tago
- Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan
| | - Yong Wang
- Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan
| | - Masahito Hayatsu
- Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan
| | - Satoshi Tsuneda
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
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Tsuchiya Y, Nakagawa T, Takahashi R. Quantification and Phylogenetic Analysis of Ammonia Oxidizers on Biofilm Carriers in a Full-Scale Wastewater Treatment Plant. Microbes Environ 2020; 35. [PMID: 32249239 PMCID: PMC7308565 DOI: 10.1264/jsme2.me19140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Biofilm carriers have been used to remove ammonia in several wastewater treatment plants (WWTPs) in Japan. However, the abundance and species of ammonia oxidizers in the biofilms formed on the surface of carriers in full-scale operational WWTP tanks remain unclear. In the present study, we conducted quantitative PCR and PCR cloning of the amoA genes of ammonia-oxidizing bacteria and archaea (AOB and AOA) and a complete ammonia oxidizer (comammox) in the biofilm formed on the carriers in a full-scale WWTP. The quantification of amoA genes showed that the abundance of AOB and comammox was markedly greater in the biofilm than in the activated sludge suspended in a tank solution of the WWTP, while AOA was not detected in the biofilm or the activated sludge. A phylogenetic analysis of amoA genes revealed that as-yet-uncultivated comammox Nitrospira and uncultured AOB Nitrosomonas were predominant in the biofilm. The present results suggest that the biofilm formed on the surface of carriers enable comammox Nitrospira and AOB Nitrosomonas to co-exist and remain in the full-scale WWTP tank surveyed in this study.
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Xu Y, Lu J, Wang Y, Liu G, Wan X, Hua Y, Zhu D, Zhao J. Diversity and abundance of comammox bacteria in the sediments of an urban lake. J Appl Microbiol 2020; 128:1647-1657. [PMID: 31989773 DOI: 10.1111/jam.14593] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 01/19/2020] [Accepted: 01/21/2020] [Indexed: 02/01/2023]
Abstract
AIMS Although comammox have been discovered in a variety of ecosystems, there are few studies in urban lakes. This paper attempted to confirm whether this ammonia-oxidizing microbe exists in urban lakes and to determine the factors influencing its existence. METHODS AND RESULTS This study investigated the diversity and abundance of comammox bacteria in sediments of a typical urban lake in China, and their ecological relationship with other ammonia-oxidizing micro-organisms. The phylogenetic analysis indicated that comammox clade A existed in the sediment of Lake Donghu, and the comammox bacteria co-existed with ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB) and anaerobic ammonia-oxidizing (anammox) bacteria in the sediment of this lake. The abundances of the ammonia monooxygenase subunit A (amoA) genes for comammox, AOA, AOB and anammox 16S rRNA were 2·43 × 108 , 1·07 × 108 , 3·24 × 107 and 3·21 × 1011 copies per gram dry sediment respectively. Moreover, the amoA gene abundance of comammox was positively correlated with that of AOA and AOB. The redundancy analysis showed that the abundance of the comammox amoA gene was negatively correlated with the concentration of main indicators for nitrogen status in both the sediment and the water column, indicating that eutrophication may inhibit the growth of comammox bacteria. CONCLUSIONS Comammox bacteria play an important ecological role in the nitrogen cycle of urban lake sediments. SIGNIFICANCE AND IMPACT OF THE STUDY Our results indicated comammox bacteria were widespread in urban lakes and eutrophication may inhibit their growth.
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Affiliation(s)
- Y Xu
- Laboratory of Eco-Environmental Engineering Research of Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, China
| | - J Lu
- Australian Rivers Institute, Griffith University, Nathan, Qld, Australia
| | - Y Wang
- State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, Beijing, China.,Department of Water Environment, China Institute of Water Resources and Hydropower Research, Beijing, China
| | - G Liu
- Laboratory of Eco-Environmental Engineering Research of Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, China
| | - X Wan
- Laboratory of Eco-Environmental Engineering Research of Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, China
| | - Y Hua
- Laboratory of Eco-Environmental Engineering Research of Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, China
| | - D Zhu
- Laboratory of Eco-Environmental Engineering Research of Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, China
| | - J Zhao
- Laboratory of Eco-Environmental Engineering Research of Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, China
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Gülay A, Fowler SJ, Tatari K, Thamdrup B, Albrechtsen HJ, Al-Soud WA, Sørensen SJ, Smets BF. DNA- and RNA-SIP Reveal Nitrospira spp. as Key Drivers of Nitrification in Groundwater-Fed Biofilters. mBio 2019; 10:e01870-19. [PMID: 31690672 DOI: 10.1128/mBio.01870-19] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Nitrification, the oxidative process converting ammonia to nitrite and nitrate, is driven by microbes and plays a central role in the global nitrogen cycle. Our earlier investigations based on 16S rRNA and amoA amplicon analysis, amoA quantitative PCR and metagenomics of groundwater-fed biofilters indicated a consistently high abundance of comammox Nitrospira Here, we hypothesized that these nonclassical nitrifiers drive ammonia-N oxidation. Hence, we used DNA and RNA stable isotope probing (SIP) coupled with 16S rRNA amplicon sequencing to identify the active members in the biofilter community when subjected to a continuous supply of NH4 + or NO2 - in the presence of 13C-HCO3 - (labeled) or 12C-HCO3 - (unlabeled). Allylthiourea (ATU) and sodium chlorate were added to inhibit autotrophic ammonia- and nitrite-oxidizing bacteria, respectively. Our results confirmed that lineage II Nitrospira dominated ammonia oxidation in the biofilter community. A total of 78 (8 by RNA-SIP and 70 by DNA-SIP) and 96 (25 by RNA-SIP and 71 by DNA-SIP) Nitrospira phylotypes (at 99% 16S rRNA sequence similarity) were identified as complete ammonia- and nitrite-oxidizing, respectively. We also detected significant HCO3 - uptake by Acidobacteria subgroup10, Pedomicrobium, Rhizobacter, and Acidovorax under conditions that favored ammonia oxidation. Canonical Nitrospira alone drove nitrite oxidation in the biofilter community, and activity of archaeal ammonia-oxidizing taxa was not detected in the SIP fractions. This study provides the first in situ evidence of ammonia oxidation by comammox Nitrospira in an ecologically relevant complex microbiome.IMPORTANCE With this study we provide the first in situ evidence of ecologically relevant ammonia oxidation by comammox Nitrospira in a complex microbiome and document an unexpectedly high H13CO3 - uptake and growth of proteobacterial and acidobacterial taxa under ammonia selectivity. This finding raises the question of whether comammox Nitrospira is an equally important ammonia oxidizer in other environments.
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Bartelme RP, Smith MC, Sepulveda-Villet OJ, Newton RJ. Component Microenvironments and System Biogeography Structure Microorganism Distributions in Recirculating Aquaculture and Aquaponic Systems. mSphere 2019; 4:e00143-19. [PMID: 31270175 DOI: 10.1128/mSphere.00143-19] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Recirculating aquaculture systems (RAS) are agroecosystems for intensive on-land cultivation of products of fisheries. Practitioners that incorporate edible plant production into RAS refer to these facilities as aquaponic systems (AP). RAS have the potential to offset declining production levels of wild global fisheries while reducing waste and product distance to market, but system optimization is needed to reduce costs. Both RAS and AP rely on microbial consortia for maintaining water quality and promoting fish/plant health, but little is known about the microorganisms actually present. This lack of knowledge prevents optimization of designs and operational controls to target the growth of beneficial microbial species or consortia. The significance of our research is in identifying the common microorganisms that inhabit production RAS and AP and the operational factors that influence which microorganisms colonize and become abundant. Identifying these organisms is a first step toward advanced control of microbial activities that improve reproducibility and reduce costs. Flowthrough and pond aquaculture system microbiome management practices aim to mitigate fish disease and stress. However, the operational success of recirculating aquaculture systems (RAS) depends directly on system microbial community activities. In RAS, each component environment is engineered for a specific microbial niche for waste management, as the water continuously flowing through the system must be processed before returning to the rearing tank. In this study, we compared waste management component microbiomes (rearing tank water, pH correction tank, solid-waste clarifier, biofilter, and degassing tower) within a commercial-scale freshwater RAS by high-throughput 16S rRNA gene sequencing. To assess consistency among freshwater RAS microbiomes, we also compared the microbial community compositions of six aquaculture and aquaponic farms. Community assemblages reflected site and source water relationships, and the presence of a hydroponic subsystem was a major community determinant. In contrast to the facility-specific community composition, some sequence variants, mainly classified into Flavobacterium, Cetobacterium, the family Sphingomonadaceae, and nitrifying guilds of ammonia-oxidizing archaea and Nitrospira, were common across all facilities. The findings of this study suggest that, independently of system design, core taxa exist across RAS rearing similar fish species but that system design informs the individual aquatic microbiome assemblages. Future RAS design would benefit from understanding the roles of these core taxa and then capitalizing on their activities to further reduce system waste/added operational controls. IMPORTANCE Recirculating aquaculture systems (RAS) are agroecosystems for intensive on-land cultivation of products of fisheries. Practitioners that incorporate edible plant production into RAS refer to these facilities as aquaponic systems (AP). RAS have the potential to offset declining production levels of wild global fisheries while reducing waste and product distance to market, but system optimization is needed to reduce costs. Both RAS and AP rely on microbial consortia for maintaining water quality and promoting fish/plant health, but little is known about the microorganisms actually present. This lack of knowledge prevents optimization of designs and operational controls to target the growth of beneficial microbial species or consortia. The significance of our research is in identifying the common microorganisms that inhabit production RAS and AP and the operational factors that influence which microorganisms colonize and become abundant. Identifying these organisms is a first step toward advanced control of microbial activities that improve reproducibility and reduce costs.
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35
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Abstract
Published PCR primers targeting the ammonia monooxygenase gene (amoA) were applied to samples from activated sludge systems operated with low dissolved oxygen (DO) to quantify total and clade-level Nitrospira that perform complete ammonium oxidation (comammox); however, we found these existing primers resulted in significant artifact-associated non-target amplification. This not only overestimated comammox amoA copies but also resulted in numerous false positive detections in the environmental samples tested, as confirmed by gel electrophoresis. Therefore, instead of attempting to quantify comammox diversity, we focused on accurately quantifying the candidate comammox species. We designed specific and sensitive primers targeting 3 candidate species: Candidatus (Ca.) Nitrospira nitrosa, Ca. N. inopinata, and Ca. N. nitrificans. The primers were tested with amoA templates of these candidate species and used to quantify comammox at the species level in low DO activated sludge systems. We found that comammox related to Ca. N. nitrosa were present and abundant in the majority of samples from low DO bioreactors and were not detected in samples from a high DO system. In addition, the greatest abundance of Ca. N. nitrosa was found in bioreactors operated with a long solids retention time. Ca. N. inopinata and Ca. N. nitrificans were only detected sporadically in these samples, indicating a minor role of these comammox in nitrification under low DO conditions.
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Affiliation(s)
| | - Daniel R. Noguera
- Department of Civil and Environmental Engineering, University of Wisconsin–Madison, Madison, WI, United States
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Xia F, Wang JG, Zhu T, Zou B, Rhee SK, Quan ZX. Ubiquity and Diversity of Complete Ammonia Oxidizers ( Comammox). Appl Environ Microbiol 2018; 84:e01390-18. [PMID: 30315079 PMCID: PMC6275355 DOI: 10.1128/aem.01390-18] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/03/2018] [Indexed: 11/20/2022] Open
Abstract
The discovery of complete ammonia oxidizers (comammox) refutes the century-old paradigm that nitrification requires the activity of two types of microbes. Determining the distribution and abundance of comammox in various environments is important for revealing the ecology of microbial nitrification within the global nitrogen cycle. In this study, the ubiquity and diversity of comammox were analyzed for samples from different types of environments, including soil, sediment, sludge, and water. The results of a two-step PCR using highly degenerate primers (THDP-PCR) and quantitative real-time PCR (qPCR) supported the relatively high abundance of comammox in nearly half of all samples tested, sometimes even outnumbering canonical ammonia-oxidizing bacteria (AOB). In addition, a relatively high proportion of comammox in tap and coastal water samples was confirmed via analysis of metagenomic data sets in public databases. The diversity of comammox was estimated by comammox-specific partial nested PCR amplification of the ammonia monooxygenase subunit A (amoA) gene, and phylogenetic analysis of comammox AmoA clearly showed a split of clade A into clades A.1 and A.2, with the proportions of clades A.1, A.2, and B differing among the various environmental samples. Moreover, compared to the amoA genes of AOB and ammonia-oxidizing archaea (AOA), the comammox amoA gene exhibited higher diversity indices. The ubiquitous distribution and high diversity of comammox indicate that they are likely overlooked contributors to nitrification in various ecosystems.IMPORTANCE The discovery of complete ammonia oxidizers (comammox), which oxidize ammonia to nitrate via nitrite, refutes the century-old paradigm that nitrification requires the activity of two types of microbes and redefines a key process in the biogeochemical nitrogen cycle. Understanding the functional relationships between comammox and other nitrifiers is important for ecological studies on the nitrogen cycle. Therefore, the diversity and contribution of comammox should be considered during ecological analyses of nitrifying microorganisms. In this study, a ubiquitous and highly diverse distribution of comammox was observed in various environmental samples, similar to the distribution of canonical ammonia-oxidizing bacteria. The proportion of comammox was relatively high in coastal water and sediment samples, whereas it was nearly undetectable in open-ocean samples. The ubiquitous distribution and high diversity of comammox indicate that these microorganisms might be important contributors to nitrification.
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Affiliation(s)
- Fei Xia
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an, China
| | - Jian-Gong Wang
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Ting Zhu
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Bin Zou
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Sung-Keun Rhee
- Department of Microbiology, Chungbuk National University, Cheongju, Republic of Korea
| | - Zhe-Xue Quan
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
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Black EM, Just CL. The Genomic Potentials of NOB and Comammox Nitrospira in River Sediment Are Impacted by Native Freshwater Mussels. Front Microbiol 2018; 9:2061. [PMID: 30233538 PMCID: PMC6131200 DOI: 10.3389/fmicb.2018.02061] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 08/13/2018] [Indexed: 11/24/2022] Open
Abstract
Freshwater mussel assemblages of the Upper Mississippi River (UMR) sequester tons of ammonia- and urea-based biodeposits each day and aerate sediment through burrowing activities, thus creating a unique niche for nitrogen (N) cycling microorganisms. This study explored how mussels impact the abundance of N-cycling species with an emphasis on Candidatus Nitrospira inopinata, the first microorganism known to completely oxidize ammonia (comammox) to nitrate. This study used metagenomic shotgun sequencing of genomic DNA to compare nitrogen cycling species in sediment under a well-established mussel assemblage and in nearby sediment without mussels. Metagenomic reads were aligned to the prokaryotic RefSeq non-redundant protein database using BLASTx, taxonomic binning was performed using the weighted lowest common ancestor algorithm, and protein-coding genes were categorized by metabolic function using the SEED subsystem. Linear discriminant analysis (LDA) effect sizes were used to determine which metagenomes and metabolic features explained the most differences between the mussel habitat sediment and sediment without mussels. Of the N-cycling species deemed differentially abundant, Nitrospira moscoviensis and “Candidatus Nitrospira inopinata” were responsible for creating a distinctive N-cycling microbiome in the mussel habitat sediment. Further investigation revealed that comammox Nitrospira had a large metabolic potential to degrade mussel biodeposits, as evidenced the top ten percent of protein-coding genes including the cytochrome c-type biogenesis protein required for hydroxylamine oxidation, ammonia monooxygenase, and urea decomposition SEED subsystems. Genetic marker analysis of these two Nitrospira taxons suggested that N. moscoviensis was most impacted by diverse carbon metabolic processes while “Candidatus Nitrospira inopinata” was most distinguished by multidrug efflux proteins (AcrB), NiFe hydrogenase (HypF) used in hydrogen oxidation and sulfur reduction coupled reactions, and a heme chaperone (CcmE). Furthermore, our research suggests that comammox and NOB Nitrospira likely coexisted by utilizing mixotrophic metabolisms. For example, “Candidatus Nitrospira inopinata” had the largest potentials for ammonia oxidation, nitrite reduction with NirK, and hydrogen oxidation, while NOB Nitrospira had the greatest potential for nitrite oxidation, and nitrate reduction possibly coupled with formate oxidation. Overall, our results suggest that this mussel habitat sediment harbors a niche for NOB and comammox Nitrospira, and ultimately impacts N-cycling in backwaters of the UMR.
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Affiliation(s)
- Ellen M Black
- Department of Civil and Environmental Engineering, University of Iowa, Iowa City, IA, United States
| | - Craig L Just
- Department of Civil and Environmental Engineering, University of Iowa, Iowa City, IA, United States
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Camejo PY, Santo Domingo J, McMahon KD, Noguera DR. Genome-Enabled Insights into the Ecophysiology of the Comammox Bacterium " Candidatus Nitrospira nitrosa". mSystems 2017; 2:e00059-17. [PMID: 28905001 DOI: 10.1128/mSystems.00059-17] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 08/15/2017] [Indexed: 02/03/2023] Open
Abstract
Nitrospira-like bacteria are among the most diverse and widespread nitrifiers in natural ecosystems and the dominant nitrite oxidizers in wastewater treatment plants (WWTPs). The recent discovery of comammox-like Nitrospira strains, capable of complete oxidation of ammonia to nitrate, raises new questions about specific traits responsible for the functional versatility and adaptation of this genus to a variety of environments. The availability of new Nitrospira genome sequences from both nitrite-oxidizing and comammox bacteria offers a way to analyze traits in different Nitrospira functional groups. Our comparative genomics analysis provided new insights into the adaptation of Nitrospira strains to specific lifestyles and environmental niches. The recently discovered comammox bacteria have the potential to completely oxidize ammonia to nitrate. These microorganisms are part of the Nitrospira genus and are present in a variety of environments, including biological nutrient removal (BNR) systems. However, the physiological traits within and between comammox and nitrite-oxidizing bacterium (NOB)-like Nitrospira species have not been analyzed in these ecosystems. In this study, we identified Nitrospira strains dominating the nitrifying community of a sequencing batch reactor (SBR) performing BNR under microaerobic conditions. We recovered metagenome-derived draft genomes from two Nitrospira strains: (i) Nitrospira sp. strain UW-LDO-01, a comammox-like organism classified as “Candidatus Nitrospira nitrosa,” and (ii) Nitrospira sp. strain UW-LDO-02, a nitrite-oxidizing strain belonging to the Nitrospira defluvii species. A comparative genomic analysis of these strains with other Nitrospira-like genomes identified genomic differences in “Ca. Nitrospira nitrosa” mainly attributed to each strain’s niche adaptation. Traits associated with energy metabolism also differentiate comammox from NOB-like genomes. We also identified several transcriptionally regulated adaptive traits, including stress tolerance, biofilm formation, and microaerobic metabolism, which might explain survival of Nitrospira under multiple environmental conditions. Overall, our analysis expanded our understanding of the genetic functional features of “Ca. Nitrospira nitrosa” and identified genomic traits that further illuminate the phylogenetic diversity and metabolic plasticity of the Nitrospira genus. IMPORTANCENitrospira-like bacteria are among the most diverse and widespread nitrifiers in natural ecosystems and the dominant nitrite oxidizers in wastewater treatment plants (WWTPs). The recent discovery of comammox-like Nitrospira strains, capable of complete oxidation of ammonia to nitrate, raises new questions about specific traits responsible for the functional versatility and adaptation of this genus to a variety of environments. The availability of new Nitrospira genome sequences from both nitrite-oxidizing and comammox bacteria offers a way to analyze traits in different Nitrospira functional groups. Our comparative genomics analysis provided new insights into the adaptation of Nitrospira strains to specific lifestyles and environmental niches. Author Video: An author video summary of this article is available.
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Pjevac P, Schauberger C, Poghosyan L, Herbold CW, van Kessel MAHJ, Daebeler A, Steinberger M, Jetten MSM, Lücker S, Wagner M, Daims H. AmoA-Targeted Polymerase Chain Reaction Primers for the Specific Detection and Quantification of Comammox Nitrospira in the Environment. Front Microbiol 2017; 8:1508. [PMID: 28824606 PMCID: PMC5543084 DOI: 10.3389/fmicb.2017.01508] [Citation(s) in RCA: 186] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 07/27/2017] [Indexed: 12/03/2022] Open
Abstract
Nitrification, the oxidation of ammonia via nitrite to nitrate, has always been considered to be catalyzed by the concerted activity of ammonia- and nitrite-oxidizing microorganisms. Only recently, complete ammonia oxidizers ("comammox"), which oxidize ammonia to nitrate on their own, were identified in the bacterial genus Nitrospira, previously assumed to contain only canonical nitrite oxidizers. Nitrospira are widespread in nature, but for assessments of the distribution and functional importance of comammox Nitrospira in ecosystems, cultivation-independent tools to distinguish comammox from strictly nitrite-oxidizing Nitrospira are required. Here we developed new PCR primer sets that specifically target the amoA genes coding for subunit A of the distinct ammonia monooxygenase of comammox Nitrospira. While existing primers capture only a fraction of the known comammox amoA diversity, the new primer sets cover as much as 95% of the comammox amoA clade A and 92% of the clade B sequences in a reference database containing 326 comammox amoA genes with sequence information at the primer binding sites. Application of the primers to 13 samples from engineered systems (a groundwater well, drinking water treatment and wastewater treatment plants) and other habitats (rice paddy and forest soils, rice rhizosphere, brackish lake sediment and freshwater biofilm) detected comammox Nitrospira in all samples and revealed a considerable diversity of comammox in most habitats. Excellent primer specificity for comammox amoA was achieved by avoiding the use of highly degenerate primer preparations and by using equimolar mixtures of oligonucleotides that match existing comammox amoA genes. Quantitative PCR with these equimolar primer mixtures was highly sensitive and specific, and enabled the efficient quantification of clade A and clade B comammox amoA gene copy numbers in environmental samples. The measured relative abundances of comammox Nitrospira, compared to canonical ammonia oxidizers, were highly variable across environments. The new comammox amoA-targeted primers enable more encompassing future studies of nitrifying microorganisms in diverse habitats. For example, they may be used to monitor the population dynamics of uncultured comammox organisms under changing environmental conditions and in response to altered treatments in engineered and agricultural ecosystems.
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Affiliation(s)
- Petra Pjevac
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network ‘Chemistry meets Microbiology’, University of ViennaVienna, Austria
| | - Clemens Schauberger
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network ‘Chemistry meets Microbiology’, University of ViennaVienna, Austria
| | - Lianna Poghosyan
- Department of Microbiology, Institute for Water and Wetland Research (IWWR), Radboud UniversityNijmegen, Netherlands
| | - Craig W. Herbold
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network ‘Chemistry meets Microbiology’, University of ViennaVienna, Austria
| | - Maartje A. H. J. van Kessel
- Department of Microbiology, Institute for Water and Wetland Research (IWWR), Radboud UniversityNijmegen, Netherlands
| | - Anne Daebeler
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network ‘Chemistry meets Microbiology’, University of ViennaVienna, Austria
| | - Michaela Steinberger
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network ‘Chemistry meets Microbiology’, University of ViennaVienna, Austria
| | - Mike S. M. Jetten
- Department of Microbiology, Institute for Water and Wetland Research (IWWR), Radboud UniversityNijmegen, Netherlands
| | - Sebastian Lücker
- Department of Microbiology, Institute for Water and Wetland Research (IWWR), Radboud UniversityNijmegen, Netherlands
| | - Michael Wagner
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network ‘Chemistry meets Microbiology’, University of ViennaVienna, Austria
| | - Holger Daims
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network ‘Chemistry meets Microbiology’, University of ViennaVienna, Austria
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Bartelme RP, McLellan SL, Newton RJ. Freshwater Recirculating Aquaculture System Operations Drive Biofilter Bacterial Community Shifts around a Stable Nitrifying Consortium of Ammonia-Oxidizing Archaea and Comammox Nitrospira. Front Microbiol 2017; 8:101. [PMID: 28194147 PMCID: PMC5276851 DOI: 10.3389/fmicb.2017.00101] [Citation(s) in RCA: 132] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 01/13/2017] [Indexed: 01/04/2023] Open
Abstract
Recirculating aquaculture systems (RAS) are unique engineered ecosystems that minimize environmental perturbation by reducing nutrient pollution discharge. RAS typically employ a biofilter to control ammonia levels produced as a byproduct of fish protein catabolism. Nitrosomonas (ammonia-oxidizing), Nitrospira, and Nitrobacter (nitrite-oxidizing) species are thought to be the primary nitrifiers present in RAS biofilters. We explored this assertion by characterizing the biofilter bacterial and archaeal community of a commercial scale freshwater RAS that has been in operation for >15 years. We found the biofilter community harbored a diverse array of bacterial taxa (>1000 genus-level taxon assignments) dominated by Chitinophagaceae (~12%) and Acidobacteria (~9%). The bacterial community exhibited significant composition shifts with changes in biofilter depth and in conjunction with operational changes across a fish rearing cycle. Archaea also were abundant, and were comprised solely of a low diversity assemblage of Thaumarchaeota (>95%), thought to be ammonia-oxidizing archaea (AOA) from the presence of AOA ammonia monooxygenase genes. Nitrosomonas were present at all depths and time points. However, their abundance was >3 orders of magnitude less than AOA and exhibited significant depth-time variability not observed for AOA. Phylogenetic analysis of the nitrite oxidoreductase beta subunit (nxrB) gene indicated two distinct Nitrospira populations were present, while Nitrobacter were not detected. Subsequent identification of Nitrospira ammonia monooxygenase alpha subunit genes in conjunction with the phylogenetic placement and quantification of the nxrB genotypes suggests complete ammonia-oxidizing (comammox) and nitrite-oxidizing Nitrospira populations co-exist with relatively equivalent and stable abundances in this system. It appears RAS biofilters harbor complex microbial communities whose composition can be affected directly by typical system operations while supporting multiple ammonia oxidation lifestyles within the nitrifying consortium.
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Affiliation(s)
- Ryan P Bartelme
- School of Freshwater Sciences, University of Wisconsin-Milwaukee Milwaukee, WI, USA
| | - Sandra L McLellan
- School of Freshwater Sciences, University of Wisconsin-Milwaukee Milwaukee, WI, USA
| | - Ryan J Newton
- School of Freshwater Sciences, University of Wisconsin-Milwaukee Milwaukee, WI, USA
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Pjevac P, Schauberger C, Poghosyan L, Herbold CW, van Kessel MAHJ, Daebeler A, Steinberger M, Jetten MSM, Lücker S, Wagner M, Daims H. AmoA-Targeted Polymerase Chain Reaction Primers for the Specific Detection and Quantification of Comammox Nitrospira in the Environment. Front Microbiol 2017. [PMID: 28824606 DOI: 10.1101/096891] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023] Open
Abstract
Nitrification, the oxidation of ammonia via nitrite to nitrate, has always been considered to be catalyzed by the concerted activity of ammonia- and nitrite-oxidizing microorganisms. Only recently, complete ammonia oxidizers ("comammox"), which oxidize ammonia to nitrate on their own, were identified in the bacterial genus Nitrospira, previously assumed to contain only canonical nitrite oxidizers. Nitrospira are widespread in nature, but for assessments of the distribution and functional importance of comammox Nitrospira in ecosystems, cultivation-independent tools to distinguish comammox from strictly nitrite-oxidizing Nitrospira are required. Here we developed new PCR primer sets that specifically target the amoA genes coding for subunit A of the distinct ammonia monooxygenase of comammox Nitrospira. While existing primers capture only a fraction of the known comammox amoA diversity, the new primer sets cover as much as 95% of the comammox amoA clade A and 92% of the clade B sequences in a reference database containing 326 comammox amoA genes with sequence information at the primer binding sites. Application of the primers to 13 samples from engineered systems (a groundwater well, drinking water treatment and wastewater treatment plants) and other habitats (rice paddy and forest soils, rice rhizosphere, brackish lake sediment and freshwater biofilm) detected comammox Nitrospira in all samples and revealed a considerable diversity of comammox in most habitats. Excellent primer specificity for comammox amoA was achieved by avoiding the use of highly degenerate primer preparations and by using equimolar mixtures of oligonucleotides that match existing comammox amoA genes. Quantitative PCR with these equimolar primer mixtures was highly sensitive and specific, and enabled the efficient quantification of clade A and clade B comammox amoA gene copy numbers in environmental samples. The measured relative abundances of comammox Nitrospira, compared to canonical ammonia oxidizers, were highly variable across environments. The new comammox amoA-targeted primers enable more encompassing future studies of nitrifying microorganisms in diverse habitats. For example, they may be used to monitor the population dynamics of uncultured comammox organisms under changing environmental conditions and in response to altered treatments in engineered and agricultural ecosystems.
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Affiliation(s)
- Petra Pjevac
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network 'Chemistry meets Microbiology', University of ViennaVienna, Austria
| | - Clemens Schauberger
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network 'Chemistry meets Microbiology', University of ViennaVienna, Austria
| | - Lianna Poghosyan
- Department of Microbiology, Institute for Water and Wetland Research (IWWR), Radboud UniversityNijmegen, Netherlands
| | - Craig W Herbold
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network 'Chemistry meets Microbiology', University of ViennaVienna, Austria
| | - Maartje A H J van Kessel
- Department of Microbiology, Institute for Water and Wetland Research (IWWR), Radboud UniversityNijmegen, Netherlands
| | - Anne Daebeler
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network 'Chemistry meets Microbiology', University of ViennaVienna, Austria
| | - Michaela Steinberger
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network 'Chemistry meets Microbiology', University of ViennaVienna, Austria
| | - Mike S M Jetten
- Department of Microbiology, Institute for Water and Wetland Research (IWWR), Radboud UniversityNijmegen, Netherlands
| | - Sebastian Lücker
- Department of Microbiology, Institute for Water and Wetland Research (IWWR), Radboud UniversityNijmegen, Netherlands
| | - Michael Wagner
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network 'Chemistry meets Microbiology', University of ViennaVienna, Austria
| | - Holger Daims
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network 'Chemistry meets Microbiology', University of ViennaVienna, Austria
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Pinto AJ, Marcus DN, Ijaz UZ, Bautista-de Lose Santos QM, Dick GJ, Raskin L. Metagenomic Evidence for the Presence of Comammox Nitrospira-Like Bacteria in a Drinking Water System. mSphere 2016; 1:e00054-15. [PMID: 27303675 DOI: 10.1128/mSphere.00054-15] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 12/08/2015] [Indexed: 11/23/2022] Open
Abstract
Nitrification plays an important role in regulating the concentrations of inorganic nitrogen species in a range of environments, from drinking water and wastewater treatment plants to the oceans. Until recently, aerobic nitrification was considered to be a two-step process involving ammonia-oxidizing bacteria or archaea and nitrite-oxidizing bacteria. This process requires close cooperation between these two functional guilds for complete conversion of ammonia to nitrate, without the accumulation of nitrite or other intermediates, such as nitrous oxide, a potent greenhouse gas. The discovery of a single organism with the potential to oxidize both ammonia and nitrite adds a new dimension to the current understanding of aerobic nitrification, while presenting opportunities to rethink nitrogen management in engineered systems. We report metagenomic evidence for the presence of a Nitrospira-like organism with the metabolic potential to perform the complete oxidation of ammonia to nitrate (i.e., it is a complete ammonia oxidizer [comammox]) in a drinking water system. This metagenome bin was discovered through shotgun DNA sequencing of samples from biologically active filters at the drinking water treatment plant in Ann Arbor, MI. Ribosomal proteins, 16S rRNA, and nxrA gene analyses confirmed that this genome is related to Nitrospira-like nitrite-oxidizing bacteria. The presence of the full suite of ammonia oxidation genes, including ammonia monooxygenase and hydroxylamine dehydrogenase, on a single ungapped scaffold within this metagenome bin suggests the presence of recently discovered comammox potential. Evaluations based on coverage and k-mer frequency distribution, use of two different genome-binning approaches, and nucleic acid and protein similarity analyses support the presence of this scaffold within the Nitrospira metagenome bin. The amoA gene found in this metagenome bin is divergent from those of canonical ammonia and methane oxidizers and clusters closely with the unusual amoA gene of comammox Nitrospira. This finding suggests that previously reported imbalances in abundances of nitrite- and ammonia-oxidizing bacteria/archaea may likely be explained by the capacity of Nitrospira-like organisms to completely oxidize ammonia. This finding might have significant implications for our understanding of microbially mediated nitrogen transformations in engineered and natural systems. IMPORTANCE Nitrification plays an important role in regulating the concentrations of inorganic nitrogen species in a range of environments, from drinking water and wastewater treatment plants to the oceans. Until recently, aerobic nitrification was considered to be a two-step process involving ammonia-oxidizing bacteria or archaea and nitrite-oxidizing bacteria. This process requires close cooperation between these two functional guilds for complete conversion of ammonia to nitrate, without the accumulation of nitrite or other intermediates, such as nitrous oxide, a potent greenhouse gas. The discovery of a single organism with the potential to oxidize both ammonia and nitrite adds a new dimension to the current understanding of aerobic nitrification, while presenting opportunities to rethink nitrogen management in engineered systems.
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