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Niu J, Wan Y, Ma Z, Wang Z, Dong W, Su X, Shen X, Zhai Y. Driving mechanism of different nutrient conditions on microbial mediated nitrate reduction in magnetite-present river infiltration zone. Sci Total Environ 2024; 926:171963. [PMID: 38537835 DOI: 10.1016/j.scitotenv.2024.171963] [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] [Received: 12/30/2023] [Revised: 03/07/2024] [Accepted: 03/23/2024] [Indexed: 04/17/2024]
Abstract
Significant research is focused on the ability of riparian zones to reduce groundwater nitrate contamination. Owing to the extremely high redox activity of nitrate, naturally existing electron donors, such as organic matter and iron minerals, are crucial in facilitating nitrate reduction in the riparian zone. Here, we examined the coexistence of magnetite, an iron mineral, and nitrate, a frequently observed coexisting system in sediments, to investigate nitrate reduction features at various C/N ratios and evaluate the response of microbial communities to these settings. Additionally, we aimed to use this information as a foundation for examining the effect of nutritional conditions on the nitrate reduction process in magnetite-present environments. These results emphasise the significance of organic matter in enabling dissimilatory nitrate reduction to ammonium (DNRA) and enhancing the connection between nitrate reduction and iron in sedimentary environments. In the later phases of nitrate reduction, nitrogen fixation was the prevailing process in low-carbon environments, whereas high-carbon environments tended to facilitate the breakdown of organic nitrogen. High-throughput sequencing analysis revealed a robust association between C/N ratios and alterations in microbial community composition, providing insights into notable modifications in essential functioning microorganisms. The nitrogen-fixing bacterium Ralstonia is more abundant in ecosystems with scarce organic matter. In contrast, in settings rich in organic matter, microorganisms, such as Acinetobacter and Clostridia, which may produce ammonia, play crucial roles. Moreover, the population of iron bacteria grows in such an environment. Hence, this study proposes that C/N ratios can influence Fe(II)/Fe(III) conversions and simultaneously affect the process of nitrate reduction by shaping the composition of specific microbial communities.
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Affiliation(s)
- Jia Niu
- Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, People's Republic of China; College of New Energy and Environment, Jilin University, Changchun 130021, People's Republic of China; Institute of Water Resources and Environment, Jilin University, Changchun 130021, People's Republic of China
| | - Yuyu Wan
- Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, People's Republic of China; College of New Energy and Environment, Jilin University, Changchun 130021, People's Republic of China; Institute of Water Resources and Environment, Jilin University, Changchun 130021, People's Republic of China.
| | - Zhe Ma
- Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, People's Republic of China; College of New Energy and Environment, Jilin University, Changchun 130021, People's Republic of China; Institute of Water Resources and Environment, Jilin University, Changchun 130021, People's Republic of China
| | - Zhen Wang
- Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, People's Republic of China; College of New Energy and Environment, Jilin University, Changchun 130021, People's Republic of China; Institute of Water Resources and Environment, Jilin University, Changchun 130021, People's Republic of China
| | - Weihong Dong
- Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, People's Republic of China; College of New Energy and Environment, Jilin University, Changchun 130021, People's Republic of China; Institute of Water Resources and Environment, Jilin University, Changchun 130021, People's Republic of China
| | - Xiaosi Su
- Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, People's Republic of China; College of New Energy and Environment, Jilin University, Changchun 130021, People's Republic of China; Institute of Water Resources and Environment, Jilin University, Changchun 130021, People's Republic of China
| | - Xiaofang Shen
- Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, People's Republic of China; College of New Energy and Environment, Jilin University, Changchun 130021, People's Republic of China; Institute of Water Resources and Environment, Jilin University, Changchun 130021, People's Republic of China
| | - Yuanzheng Zhai
- College of Water Sciences, Beijing Normal University, Beijing 100875, People's Republic of China
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2
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Skeba S, Snyder M, Maltman C. Metallophore Activity toward the Rare Earth Elements by Bacteria Isolated from Acid Mine Drainage Due to Coal Mining. Microorganisms 2023; 11:2672. [PMID: 38004684 PMCID: PMC10673398 DOI: 10.3390/microorganisms11112672] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 10/26/2023] [Accepted: 10/30/2023] [Indexed: 11/26/2023] Open
Abstract
The field of microbe-metal interactions has been gaining significant attention. While the direct impact of metal oxyanions on bacteria has been investigated, significantly less attention has been placed on the ability of certain microbes to 'collect' such metal ions via secreted proteins. Many bacteria possess low-weight molecules called siderophores, which collect Fe from the environment to be brought back to the cell. However, some appear to have additional roles, including binding other metals, termed 'metallophores'. Microbes can remove/sequester these from their surroundings, but the breadth of those that can be removed is still unknown. Using the Chromeazurol S assay, we identified eight isolates, most belonging to the genus Pseudomonas, possessing siderophore activity, mainly from sites impacted by coal mine drainage, also possessing a metallophore activity toward the rare earth elements that does not appear to be related to ionic radii or previously reported EC50 concentrations for E. coli. We found the strength of metallophore activity towards these elements was as follows: Pr > Sc > Eu > Tm > Tb > Er > Yb > Ce > Lu > Sm > Ho > La > Nd > Dy > Gd > Y. This is the first study to investigate such activity and indicates bacteria may provide a means of removal/recovery of these critical elements.
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Affiliation(s)
| | | | - Chris Maltman
- Department of Biology, Slippery Rock University, Slippery Rock, PA 16057, USA
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3
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Wei Y, Yu S, Guo Q, Missen OP, Xia X. Microbial mechanisms to transform the super-trace element tellurium: a systematic review and discussion of nanoparticulate phases. World J Microbiol Biotechnol 2023; 39:262. [PMID: 37507604 PMCID: PMC10382350 DOI: 10.1007/s11274-023-03704-2] [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: 05/25/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023]
Abstract
Tellurium is a super-trace metalloid on Earth. Owing to its excellent physical and chemical properties, it is used in industries such as metallurgy and manufacturing, particularly of semiconductors and - more recently - solar panels. As the global demand for tellurium rises, environmental issues surrounding tellurium have recently aroused concern due to its high toxicity. The amount of tellurium released to the environment is increasing, and microorganisms play an important role in the biogeochemical cycling of environmental tellurium. This review focuses on novel developments on tellurium transformations driven by microbes and includes the following sections: (1) history and applications of tellurium; (2) toxicity of tellurium; (3) microbial detoxification mechanisms against soluble tellurium anions including uptake, efflux and methods of reduction, and reduced ability to cope with oxidation stress or repair damaged DNA; and (4) the characteristics and applications of tellurium nanoparticles (TeNPs) produced by microbes. This review raises the awareness of microorganisms in tellurium biogeochemical cycling and the growing applications for microbial tellurium nanoparticles.
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Affiliation(s)
- Yuru Wei
- Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Hubei Engineering Research Center of Characteristic Wild Vegetable Breeding and Comprehensive Utilization Technology, Huangshi Key Laboratory of Lake Environmental Protection and Sustainable Utilization of Resources, Hubei Normal University, Huangshi, P. R. China
| | - Sihan Yu
- Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Hubei Engineering Research Center of Characteristic Wild Vegetable Breeding and Comprehensive Utilization Technology, Huangshi Key Laboratory of Lake Environmental Protection and Sustainable Utilization of Resources, Hubei Normal University, Huangshi, P. R. China
| | - Qian Guo
- Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Hubei Engineering Research Center of Characteristic Wild Vegetable Breeding and Comprehensive Utilization Technology, Huangshi Key Laboratory of Lake Environmental Protection and Sustainable Utilization of Resources, Hubei Normal University, Huangshi, P. R. China
| | - Owen P Missen
- Centre for Ore Deposit and Earth Sciences, University of Tasmania, TAS, Private Bag 79, Hobart, 7001, Australia.
| | - Xian Xia
- Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Hubei Engineering Research Center of Characteristic Wild Vegetable Breeding and Comprehensive Utilization Technology, Huangshi Key Laboratory of Lake Environmental Protection and Sustainable Utilization of Resources, Hubei Normal University, Huangshi, P. R. China.
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4
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Maltman C, Kuzyk SB, Kyndt JA, Lengyel G, Yurkov V. Shewanella metallivivens sp. nov., a deep-sea hydrothermal vent tube worm endobiont capable of dissimilatory anaerobic metalloid oxyanion reduction. Int J Syst Evol Microbiol 2023; 73. [PMID: 37477965 DOI: 10.1099/ijsem.0.005980] [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] [Indexed: 07/22/2023] Open
Abstract
A polyphasic taxonomic study was carried out on a Gram-stain-negative and rod-shaped strain, ER-Te-42B-LightT, isolated from the tissue of a tube worm, Riftia pachyptila, collected near a deep-sea hydrothermal vent of the Juan de Fuca Ridge in the Pacific Ocean. This bacterium was capable of performing anaerobic respiration using tellurite, tellurate, selenite and orthovanadate as terminal electron acceptors. While facultatively anaerobic, it could aerobically resist tellurite, selenite and orthovanadate up to 2000, 7000 and 10000 µg ml-1, respectively, reducing each oxide to elemental forms. Nearly complete 16S rRNA gene sequence similarity related the strain to Shewanella, with 98.8 and 98.7 % similarity to Shewanella basaltis and Shewanella algicola, respectively. The dominant fatty acids were C16 : 0 and C16 : 1. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol and MK-7 was the predominant quinone. DNA G+C content was 42.5 mol%. Computation of average nucleotide identity and digital DNA-DNA hybridization values with the closest phylogenetic neighbours of ER-Te-42B-LightT revealed genetic divergence at the species level, which was further substantiated by differences in several physiological characteristics. Based on the obtained results, this bacterium was assigned to the genus Shewanella as a new species with the name Shewanella metallivivens sp. nov., type strain ER-Te-42B-LightT (=VKM B-3580T=DSM 113370T).
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Affiliation(s)
- Chris Maltman
- Department of Biology, Slippery Rock University, Slippery Rock, Pennsylvania, USA
| | - Steven B Kuzyk
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - John A Kyndt
- College of Science and Technology, Bellevue University, Bellevue, NE, USA
| | - George Lengyel
- Department of Chemistry, Slippery Rock University, Slippery Rock, Pennsylvania, USA
| | - Vladimir Yurkov
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
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5
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Lashani E, Amoozegar MA, Turner RJ, Moghimi H. Use of Microbial Consortia in Bioremediation of Metalloid Polluted Environments. Microorganisms 2023; 11:microorganisms11040891. [PMID: 37110315 PMCID: PMC10143001 DOI: 10.3390/microorganisms11040891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 03/08/2023] [Accepted: 03/13/2023] [Indexed: 03/31/2023] Open
Abstract
Metalloids are released into the environment due to the erosion of the rocks or anthropogenic activities, causing problems for human health in different world regions. Meanwhile, microorganisms with different mechanisms to tolerate and detoxify metalloid contaminants have an essential role in reducing risks. In this review, we first define metalloids and bioremediation methods and examine the ecology and biodiversity of microorganisms in areas contaminated with these metalloids. Then we studied the genes and proteins involved in the tolerance, transport, uptake, and reduction of these metalloids. Most of these studies focused on a single metalloid and co-contamination of multiple pollutants were poorly discussed in the literature. Furthermore, microbial communication within consortia was rarely explored. Finally, we summarized the microbial relationships between microorganisms in consortia and biofilms to remove one or more contaminants. Therefore, this review article contains valuable information about microbial consortia and their mechanisms in the bioremediation of metalloids.
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Affiliation(s)
- Elham Lashani
- Extremophiles Laboratory, Department of Microbiology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran 14178-64411, Iran;
| | - Mohammad Ali Amoozegar
- Extremophiles Laboratory, Department of Microbiology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran 14178-64411, Iran;
- Correspondence: (M.A.A.); (H.M.); Tel.: +98-21-66415495 (H.M.)
| | - Raymond J. Turner
- Microbial Biochemistry Laboratory, Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada;
| | - Hamid Moghimi
- Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran 14178-64411, Iran
- Correspondence: (M.A.A.); (H.M.); Tel.: +98-21-66415495 (H.M.)
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6
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Remick KA, Helmann JD. The elements of life: A biocentric tour of the periodic table. Adv Microb Physiol 2023; 82:1-127. [PMID: 36948652 PMCID: PMC10727122 DOI: 10.1016/bs.ampbs.2022.11.001] [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] [Indexed: 01/31/2023]
Abstract
Living systems are built from a small subset of the atomic elements, including the bulk macronutrients (C,H,N,O,P,S) and ions (Mg,K,Na,Ca) together with a small but variable set of trace elements (micronutrients). Here, we provide a global survey of how chemical elements contribute to life. We define five classes of elements: those that are (i) essential for all life, (ii) essential for many organisms in all three domains of life, (iii) essential or beneficial for many organisms in at least one domain, (iv) beneficial to at least some species, and (v) of no known beneficial use. The ability of cells to sustain life when individual elements are absent or limiting relies on complex physiological and evolutionary mechanisms (elemental economy). This survey of elemental use across the tree of life is encapsulated in a web-based, interactive periodic table that summarizes the roles chemical elements in biology and highlights corresponding mechanisms of elemental economy.
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Affiliation(s)
- Kaleigh A Remick
- Department of Microbiology, Cornell University, New York, NY, United States
| | - John D Helmann
- Department of Microbiology, Cornell University, New York, NY, United States.
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7
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Chen Y, Li X, Liu T, Li F, Sun W, Young LY, Huang W. Metagenomic analysis of Fe(II)-oxidizing bacteria for Fe(III) mineral formation and carbon assimilation under microoxic conditions in paddy soil. Sci Total Environ 2022; 851:158068. [PMID: 35987227 DOI: 10.1016/j.scitotenv.2022.158068] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [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: 05/19/2022] [Revised: 08/08/2022] [Accepted: 08/12/2022] [Indexed: 06/15/2023]
Abstract
Microbially mediated Fe(II) oxidation is prevalent and thought to be central to many biogeochemical processes in paddy soils. However, we have limited insights into the Fe(II) oxidation process in paddy fields, considered the world's largest engineered wetland, where microoxic conditions are ubiquitous. In this study, microaerophilic Fe(II) oxidizing bacteria (FeOB) from paddy soil were enriched in gradient tubes with FeS, FeCO3, and Fe3(PO4)2 as iron sources to investigate their capacity for Fe(II) oxidation and carbon assimilation. Results showed that the highest rate of Fe(II) oxidation (k = 0.836 mM d-1) was obtained in the FeCO3 tubes, and cells grown in the Fe3(PO4)2 tubes yielded maximum assimilation amounts of 13C-NaHCO3 of 1.74% on Day 15. Amorphous Fe(III) oxides were found in all the cell bands with iron substrates as a result of microbial Fe(II) oxidation. Metagenomics analysis of the enriched microbes targeted genes encoding iron oxidase Cyc2, oxygen-reducing terminal oxidase, and ribulose-bisphosphate carboxylase, with results indicated that the potential Fe(II) oxidizers include nitrate-reducing FeOB (Dechloromonas and Thiobacillus), Curvibacter, and Magnetospirillum. By combining cultivation-dependent and metagenomic approaches, our results found a number of FeOB from paddy soil under microoxic conditions, which provide insight into the complex biogeochemical interactions of iron and carbon within paddy fields. The contribution of the FeOB to the element cycling in rice-growing regions deserves further investigation.
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Affiliation(s)
- Yating Chen
- Institute for Disaster Management and Reconstruction, Sichuan University-Hong Kong Polytechnic University, Chengdu 610207, China
| | - Xiaomin Li
- SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China.
| | - Tongxu Liu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-Environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Fangbai Li
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-Environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China.
| | - Weimin Sun
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-Environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Lily Y Young
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ 08901, USA
| | - Weilin Huang
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ 08901, USA
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Goff JL, Boyanov MI, Kemner KM, Yee N. The role of cysteine in tellurate reduction and toxicity. Biometals 2021; 34:937-946. [PMID: 34255250 DOI: 10.1007/s10534-021-00319-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 05/13/2021] [Indexed: 11/29/2022]
Abstract
The tellurium oxyanion tellurate is toxic to living organisms even at low concentrations; however, its mechanism of toxicity is poorly understood. Here, we show that exposure of Escherichia coli K-12 to tellurate results in reduction to elemental tellurium (Te[0]) and the formation of intracellular reactive oxygen species (ROS). Toxicity assays performed with E. coli indicated that pre-oxidation of the intracellular thiol pools increases cellular resistance to tellurate-suggesting that intracellular thiols are important in tellurate toxicity. X-ray absorption spectroscopy experiments demonstrated that cysteine reduces tellurate to elemental tellurium. This redox reaction was found to generate superoxide anions. These results indicate that tellurate reduction to Te(0) by cysteine is a source of ROS in the cytoplasm of tellurate-exposed cells.
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Affiliation(s)
- Jennifer L Goff
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, 08854, USA.
| | - Maxim I Boyanov
- Bulgarian Academy of Sciences, Institute of Chemical Engineering, 1113, Sofia, Bulgaria.,Biosciences Division, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Kenneth M Kemner
- Biosciences Division, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Nathan Yee
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, 08854, USA.,Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
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9
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Maltman C, Yurkov V. Extreme Environments and High-Level Bacterial Tellurite Resistance. Microorganisms 2019; 7:E601. [PMID: 31766694 DOI: 10.3390/microorganisms7120601] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [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: 10/28/2019] [Revised: 11/19/2019] [Accepted: 11/20/2019] [Indexed: 01/10/2023] Open
Abstract
Bacteria have long been known to possess resistance to the highly toxic oxyanion tellurite, most commonly though reduction to elemental tellurium. However, the majority of research has focused on the impact of this compound on microbes, namely E. coli, which have a very low level of resistance. Very little has been done regarding bacteria on the other end of the spectrum, with three to four orders of magnitude greater resistance than E. coli. With more focus on ecologically-friendly methods of pollutant removal, the use of bacteria for tellurite remediation, and possibly recovery, further highlights the importance of better understanding the effect on microbes, and approaches for resistance/reduction. The goal of this review is to compile current research on bacterial tellurite resistance, with a focus on high-level resistance by bacteria inhabiting extreme environments.
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10
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Wells M, McGarry J, Gaye MM, Basu P, Oremland RS, Stolz JF. Respiratory Selenite Reductase from Bacillus selenitireducens Strain MLS10. J Bacteriol 2019; 201:e00614-18. [PMID: 30642986 DOI: 10.1128/JB.00614-18] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 01/03/2019] [Indexed: 11/20/2022] Open
Abstract
The putative respiratory selenite [Se(IV)] reductase (Srr) from Bacillus selenitireducens MLS10 has been identified through a polyphasic approach involving genomics, proteomics, and enzymology. Nondenaturing gel assays were used to identify Srr in cell fractions, and the active band was shown to contain a single protein of 80 kDa. The protein was identified through liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a homolog of the catalytic subunit of polysulfide reductase (PsrA). It was found to be encoded as part of an operon that contains six genes that we designated srrE, srrA, srrB, srrC, srrD, and srrF SrrA is the catalytic subunit (80 kDa), with a twin-arginine translocation (TAT) leader sequence indicative of a periplasmic protein and one putative 4Fe-4S binding site. SrrB is a small subunit (17 kDa) with four putative 4Fe-4S binding sites, SrrC (43 kDa) is an anchoring subunit, and SrrD (24 kDa) is a chaperon protein. Both SrrE (38 kDa) and SrrF (45 kDa) were annotated as rhodanese domain-containing proteins. Phylogenetic analysis revealed that SrrA belonged to the PsrA/PhsA clade but that it did not define a distinct subgroup, based on the putative homologs that were subsequently identified from other known selenite-respiring bacteria (e.g., Desulfurispirillum indicum and Pyrobaculum aerophilum). The enzyme appeared to be specific for Se(IV), showing no activity with selenate, arsenate, or thiosulfate, with a Km of 145 ± 53 μM, a V max of 23 ± 2.5 μM min-1, and a k cat of 23 ± 2.68 s-1 These results further our understanding of the mechanisms of selenium biotransformation and its biogeochemical cycle.IMPORTANCE Selenium is an essential element for life, with Se(IV) reduction a key step in its biogeochemical cycle. This report identifies for the first time a dissimilatory Se(IV) reductase, Srr, from a known selenite-respiring bacterium, the haloalkalophilic Bacillus selenitireducens strain MLS10. The work extends the versatility of the complex iron-sulfur molybdoenzyme (CISM) superfamily in electron transfer involving chalcogen substrates with different redox potentials. Further, it underscores the importance of biochemical and enzymological approaches in establishing the functionality of these enzymes.
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11
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Gülay A, Çekiç Y, Musovic S, Albrechtsen HJ, Smets BF. Diversity of Iron Oxidizers in Groundwater-Fed Rapid Sand Filters: Evidence of Fe(II)-Dependent Growth by Curvibacter and Undibacterium spp. Front Microbiol 2018; 9:2808. [PMID: 30559723 PMCID: PMC6287000 DOI: 10.3389/fmicb.2018.02808] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [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: 08/21/2018] [Accepted: 10/31/2018] [Indexed: 11/13/2022] Open
Abstract
Although earlier circumstantial observations have suggested the presence of iron oxidizing bacteria (IOB) in groundwater-fed rapid sand filters (RSF), ferrous iron (Fe(II)) oxidation in this environment is often considered a chemical process due to the highly oxic and circumneutral pH conditions. The low water temperature (5-10°C), typical of groundwaters, on the other hand, may reduce the rates of chemical Fe(II) oxidation, which may allow IOB to grow and compete with chemical Fe(II) oxidation. Hence, we hypothesized that IOB are active and abundant in groundwater-fed RSFs. Here, we applied a combination of cultivation and molecular approaches to isolate, quantify, and confirm the growth of IOB from groundwater-fed RSFs, operated at different influent Fe(II) concentrations. Isolates related to Undibacterium and Curvibacter were identified as novel IOB lineages. Gallionella spp. were dominant in all waterworks, whereas Ferriphaselus and Undibacterium were dominant at pre-filters of waterworks receiving groundwaters with high (>2 mg/l) Fe(II) concentrations. The high density and diversity of IOB in groundwater-fed RSFs suggest that neutrophilic IOB may not be limited to oxic/anoxic interfaces.
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Affiliation(s)
- Arda Gülay
- Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark.,Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, United States
| | - Yağmur Çekiç
- Department of Environmental Engineering, Istanbul Technical University, Istanbul, Turkey
| | | | - Hans-Jørgen Albrechtsen
- Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Barth F Smets
- Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark
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12
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Maltman C, Yurkov V. Bioremediation potential of bacteria able to reduce high levels of selenium and tellurium oxyanions. Arch Microbiol 2018; 200:1411-1417. [DOI: 10.1007/s00203-018-1555-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/11/2018] [Accepted: 07/17/2018] [Indexed: 11/24/2022]
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13
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Maltman C, Donald LJ, Yurkov V. Two distinct periplasmic enzymes are responsible for tellurite/tellurate and selenite reduction by strain ER-Te-48 associated with the deep sea hydrothermal vent tube worms at the Juan de Fuca Ridge black smokers. Arch Microbiol 2017; 199:1113-1120. [PMID: 28432382 DOI: 10.1007/s00203-017-1382-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [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: 01/25/2017] [Revised: 03/27/2017] [Accepted: 04/17/2017] [Indexed: 11/27/2022]
Abstract
Strain ER-Te-48 isolated from a deep-ocean hydrothermal vent tube worm is capable of resisting and reducing extremely high levels of tellurite, tellurate, and selenite, which are used for respiration anaerobically. Tellurite and tellurate reduction is accomplished by a periplasmic enzyme of 215 kDa comprised of 3 subunits (74, 42, and 25 kDa) in a 2:1:1 ratio. The optimum pH and temperature for activity is 8.0 and 35 °C, respectively. Tellurite reduction has a V max of 5.6 µmol/min/mg protein and a K m of 3.9 mM. In the case of the tellurate reaction, V max and K m were 2.6 µmol/min/mg protein and 2.6 mM, respectively. Selenite reduction is carried out by another periplasmic enzyme with a V max of 2.8 µmol/min/mg protein, K m of 12.1 mM, and maximal activity at pH 6.0 and 38 °C. This protein is 165 kDa and comprised of 3 subunits of 98, 44, and 23 kDa in a 1:1:1 ratio.
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Affiliation(s)
- Chris Maltman
- Department of Microbiology, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - Lynda J Donald
- Department of Microbiology, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - Vladimir Yurkov
- Department of Microbiology, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
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