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Zeng J, Tong Z, Li Z, Liu Y, Xie L, Wang T, Li S, Li L. Complete degradation of polycyclic antibiotic methacycline by a micro/nanostructured biogenic Mn oxide composite from engineered Mn(II)-oxidizing Pseudomonas sp. MB04B. Microbiol Spectr 2025:e0161124. [PMID: 40377307 DOI: 10.1128/spectrum.01611-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Accepted: 04/04/2025] [Indexed: 05/18/2025] Open
Abstract
The misuse and improper disposal of methacycline (MTC), a widely used broad-spectrum antibiotic in human clinical settings and livestock production, poses significant threats to both human health and the ecological environment. In this study, a wild-type Mn(II)-oxidizing Pseudomonas strain MB04B was modified through multiple gene deletions, leading to a maximum 35% increase in Mn oxide deposit amount (MnODA) in the engineered strain MB04R-14, and accelerated formation of biogenic Mn oxide (BMO) aggregates, which exhibited the capability to degrade and detoxify MTC completely. After constructing a mini-Tn5 transposon insertion mutant library and screening for MnODA-increased mutants, a total of 10 target genes located in the corresponding mutant loci were identified using the high-efficiency thermal asymmetric interlaced PCR (hiTAIL-PCR) method. These genes were systematically knocked out singly or in multiple combinations, and the highest MnODA-promoted mutant (MB04R-14) was obtained, in which seven genes were knocked out. Following the characterization of the BMO aggregate complex formed in MB04R-14 as a micro-/nanostructured ramsdellite (MnO2) composite through means of several analysis methods, the complex was assessed for MTC degradation under laboratory trials. Complete MTC degradation was revealed after 24 h of treatment with the BMO complex, and the metal ions Mg2+, Cu2+, Ni2+, and Co2+ significantly inhibited MTC degradation efficiency. Liquid chromatography-mass spectrometry identified three intermediates in the degradation pathway, and a possible degradation-metabolic pathway of MTC by the BMO complex was proposed. Finally, the residual antibiotic activity, continuous degradation cycle performance, and treatment of MTC-containing hospital wastewater were evaluated. IMPORTANCE Due to the common usage and recalcitrance to degradation, methacycline is often found in various surface water and wastewater as a persistent antibiotic toxicant, posing significant risks to the environment and public health. By engineering a Pseudomonas strain, we developed a dynamic oxidative composite comprising engineered Pseudomonas cells and biogenic Mn oxides. This system not only enhances oxidative capacities but also accelerates the formation of biogenic Mn oxides, leading to the complete degradation of methacycline. The findings highlight the potential of engineered Pseudomonas strain as a sustainable solution for mitigating antibiotic pollution, thereby contributing to cleaner water resources and protecting ecosystems.
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Affiliation(s)
- Jie Zeng
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Zhenghu Tong
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Zhi Li
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Yongxuan Liu
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Li Xie
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Tan Wang
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Shiwei Li
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Lin Li
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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Jones I, Vermillion D, Tracy C, Denton R, Davis R, Geszvain K. Isolation, characterization, and genetic manipulation of cold-tolerant, manganese-oxidizing Pseudomonas sp. strains. Appl Environ Microbiol 2024; 90:e0051024. [PMID: 39212379 PMCID: PMC11409713 DOI: 10.1128/aem.00510-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 07/31/2024] [Indexed: 09/04/2024] Open
Abstract
Manganese-oxidizing bacteria (MnOB) produce Mn oxide minerals that can be used by humans for bioremediation, but the purpose for the bacterium is less clear. This study describes the isolation and characterization of cold-tolerant MnOB strains isolated from a compost pile in Morris, Minnesota, USA: Pseudomonas sp. MS-1 and DSV-1. The strains were preliminarily identified as members of species Pseudomonas psychrophila by 16S rRNA analysis and a multi-locus phylogenetic study using a database of 88 genomes from the Pseudomonas genus. However, the average nucleotide identity between these strains and the P. psychrophila sp. CF149 type strain was less than 93%. Thus, the two strains are members of a novel species that diverged from P. psychrophila. DSV-1 and MS-1 are cold tolerant; both grow at 4°C but faster at 24°C. Unlike the mesophilic MnOB P. putida GB-1, both strains are capable of robustly oxidizing Mn at low temperatures. Both DSV-1 and MS-1 genomes contain homologs of several Mn oxidation genes found in P. putida GB-1 (mnxG, mcoA, mnxS1, mnxS2, and mnxR). Random mutagenesis by transposon insertion was successfully performed in both strains and identified genes involved in Mn oxidation that were similar to those found in P. putida GB-1. Our results show that MnOB can be isolated from compost, supporting a role for Mn oxidation in plant waste degradation. The novel isolates Pseudomonas spp. DSV-1 and MS-1 both can oxidize Mn at low temperature and likely employ similar mechanisms and regulation as P. putida GB-1.IMPORTANCEBiogenic Mn oxides have high sorptive capacity and are strong oxidants. These two characteristics make these oxides and the microbes that make them attractive tools for the bioremediation of wastewater and contaminated environments. Identifying MnOB that can be used for bioremediation is an active area of research. As cold-tolerant MnOB, Pseudomonas sp. DSV-1 and MS-1 have the potential to expand the environmental conditions in which biogenic Mn oxide bioremediation can be performed. The similarity of these organisms to the well-characterized MnOB P. putida GB-1 and the ability to manipulate their genomes raise the possibility of modifying them to improve their bioremediation ability.
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Affiliation(s)
- Ian Jones
- Department of Biological Sciences, California State University, Chico, California, USA
| | - Duncan Vermillion
- Division of Science and Math, University of Minnesota, Morris, Minnesota, USA
| | - Chase Tracy
- Department of Biological Sciences, California State University, Chico, California, USA
| | - Robert Denton
- Department of Biology, Marian University, Indianapolis, Indiana, USA
| | - Rick Davis
- Texas State University, NASA Johnson Space Center, Houston, Texas, USA
| | - Kati Geszvain
- Department of Biological Sciences, California State University, Chico, California, USA
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Jiang L, Tang Y, Lu Y, Chen X, Wu X, Luo P, Shiels HA. In situ phytoextraction of Mn and NH 4+-N from aqueous electrolytic manganese residue solution by Pistia stratiotes: Effects of Fe/Co presence and rhizospheric microbe synergistic involvement. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 355:124177. [PMID: 38763295 DOI: 10.1016/j.envpol.2024.124177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 04/14/2024] [Accepted: 05/16/2024] [Indexed: 05/21/2024]
Abstract
The electrolytic manganese industry produces a large amount of electrolytic manganese residue (EMR). Soluble Mn, NH4+-N, and other pollutants may be released from the open-air stacked EMR and transported to the environment along with rainfall or surface runoff. Aqueous EMR solution (AES) generally contains various elements required for plant growth, and phytoremediation can be applied to remove these pollutants from AES. Since the contents of Fe and Co vary greatly in AES depending on the ore sources as well as the pre-treatment processes, the presence of bioavailable Fe and Co at different levels may affect plant growth, the rhizosphere microbes, and pollutant removal. The present study investigated the in-situ removal of Mn(II) and NH4+-N from AES solution using free floating aquatic plant Pistia stratiotes, focusing especially on the effects of Fe/Co presence and rhizospheric microbe synergistic involvement on contaminant removal. The results showed that 69.08% of Mn and 94.99% of NH4+-N were removed by P. stratiotes in 24 d. Both the presence of Fe(II) and Co(II) facilitated the Mn(II) immobilization and increased Mn(II) removal by 19-31% due to the enhanced peroxidase activity and the increased Mn accumulating in roots The complete removal of Mn from AES was found in the presence of Fe(II) at 2 mg L-1 or Co(II) at 0.5 mg L-1 and more than 51% accumulated Mn in the roots was stored in the vacuole and cytoplasm. BioMnOx was found on the surface of the roots, revealing that rhizofiltration, rhizospheric plaque/biofilm formation, and Mn biogeochemical cycle exert synergic effects on Mn(II) immobilization. The findings of the present study demonstrate the feasibility of using P. stratiotes in the treatment of aqueous EMR solutions and the presence of an appropriate amount of bio-available Fe and Co can promote the removal of Mn(II) and NH4+-N.
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Affiliation(s)
- Lu Jiang
- School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection, Education Department of Guangxi Zhuang Autonomous Region, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Emerging Contaminants Monitoring, Early Warning and Environmental Health Risk Assessment, Guangxi University, Nanning, 530004, China
| | - Yankui Tang
- School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection, Education Department of Guangxi Zhuang Autonomous Region, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Emerging Contaminants Monitoring, Early Warning and Environmental Health Risk Assessment, Guangxi University, Nanning, 530004, China.
| | - Yanyi Lu
- School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection, Education Department of Guangxi Zhuang Autonomous Region, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Emerging Contaminants Monitoring, Early Warning and Environmental Health Risk Assessment, Guangxi University, Nanning, 530004, China
| | - Xinyu Chen
- School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection, Education Department of Guangxi Zhuang Autonomous Region, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Emerging Contaminants Monitoring, Early Warning and Environmental Health Risk Assessment, Guangxi University, Nanning, 530004, China
| | - Xinying Wu
- School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection, Education Department of Guangxi Zhuang Autonomous Region, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Emerging Contaminants Monitoring, Early Warning and Environmental Health Risk Assessment, Guangxi University, Nanning, 530004, China
| | - Penghong Luo
- School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection, Education Department of Guangxi Zhuang Autonomous Region, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Emerging Contaminants Monitoring, Early Warning and Environmental Health Risk Assessment, Guangxi University, Nanning, 530004, China
| | - Holly Alice Shiels
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine, and Health, University of Manchester, Manchester, M13 9PL, United Kingdom
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Farda B, Vaccarelli I, Ercole C, Djebaili R, Del Gallo M, Pellegrini M. Exploring structure, microbiota, and metagenome functions of epigean and hypogean black deposits by microscopic, molecular and bioinformatic approaches. Sci Rep 2022; 12:19405. [PMID: 36371463 PMCID: PMC9653421 DOI: 10.1038/s41598-022-24159-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 11/10/2022] [Indexed: 11/13/2022] Open
Abstract
This study revealed how Bacteria and Archaea communities and their metabolic functions differed between two groups of black deposits identified in gorge and cave environments. Scanning electron microscopy coupled with energy dispersive spectroscopy was used to analyse the presence of microbial biosignatures and the elemental composition of samples. Metabarcoding of the V3-V4 regions of 16S rRNA was used to investigate Bacteria and Archaea communities. Based on 16S rRNA sequencing results, PICRUSt software was used to predict metagenome functions. Micrographs showed that samples presented microbial biosignatures and microanalyses highlighted Mn concretions and layers on Al-Si surfaces. The 16S rRNA metabarcoding alpha-diversity metrics showed similar Simpson's and Shannon indices and different values of the Chao-1 index. The amplicon sequence variants (ASVs) analysis at the different taxonomic levels showed a diverse genera composition. However, the communities of all samples shared the presence of uncultured ASVs belonging to the Gemmatales family (Phylogenesis: Gemmataceae; Planctomycetes; Planctomycetota; Bacteria). The predicted metagenome functions analysis revealed diverse metabolic profiles of the Cave and Gorge groups. Genes coding for essential Mn metabolism were present in all samples. Overall, the findings on structure, microbiota, and predicted metagenome functions showed a similar microbial contribution to epigean and hypogean black deposits Mn metabolism.
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Affiliation(s)
- Beatrice Farda
- grid.158820.60000 0004 1757 2611Department of Life, Health and Environmental Sciences, University of L’Aquila, L’Aquila, Italy
| | - Ilaria Vaccarelli
- grid.158820.60000 0004 1757 2611Department of Life, Health and Environmental Sciences, University of L’Aquila, L’Aquila, Italy
| | - Claudia Ercole
- grid.158820.60000 0004 1757 2611Department of Life, Health and Environmental Sciences, University of L’Aquila, L’Aquila, Italy
| | - Rihab Djebaili
- grid.158820.60000 0004 1757 2611Department of Life, Health and Environmental Sciences, University of L’Aquila, L’Aquila, Italy
| | - Maddalena Del Gallo
- grid.158820.60000 0004 1757 2611Department of Life, Health and Environmental Sciences, University of L’Aquila, L’Aquila, Italy
| | - Marika Pellegrini
- grid.158820.60000 0004 1757 2611Department of Life, Health and Environmental Sciences, University of L’Aquila, L’Aquila, Italy
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Gawas VS, Shivaramu MS, Damare SR, Pujitha D, Meena RM, Shenoy BD. Diversity and extracellular enzyme activities of heterotrophic bacteria from sediments of the Central Indian Ocean Basin. Sci Rep 2019; 9:9403. [PMID: 31253859 PMCID: PMC6599205 DOI: 10.1038/s41598-019-45792-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 05/07/2019] [Indexed: 11/09/2022] Open
Abstract
Sedimentary bacteria play a role in polymetallic nodule formation and growth. There are, however, limited reports on bacterial diversity in nodule-rich areas of the Central Indian Ocean Basin (CIOB). In this study, bacterial abundance in thirteen sediment cores collected from the CIOB was enumerated, followed by phylogenetic characterisation and, screening of select heterotrophic bacteria for extracellular enzyme activities. Total bacterial counts (TBC) were in the order of 107 cells g-1; there was a significant difference (p > 0.05) among the cores but not within the sub-sections of the cores. The retrievable heterotrophic counts ranged from non-detectable to 5.33 × 105 g-1; the heterotrophic bacteria clustered within the phyla Firmicutes, Proteobacteria and Actinobacteria. Bacillus was the most abundant genus. The extracellular enzyme activities were in the order: amylase > lipase > protease > phosphatase > Dnase > urease. Major findings are compared with previous studies from the CIOB and other areas.
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Affiliation(s)
- Vijayshree S Gawas
- Biological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, 403004, Goa, India
| | - Mamatha S Shivaramu
- Biological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, 403004, Goa, India.
| | - Samir R Damare
- Biological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, 403004, Goa, India
| | - Devagudi Pujitha
- CSIR-National Institute of Oceanography Regional Centre, 176, Lawson's Bay Colony, Visakhapatnam, 530017, Andhra Pradesh, India.,Department of Bioinformatics, Karunya University, Coimbatore, 611114, Tamil Nadu, India
| | - Ram Murti Meena
- Biological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, 403004, Goa, India
| | - Belle Damodara Shenoy
- CSIR-National Institute of Oceanography Regional Centre, 176, Lawson's Bay Colony, Visakhapatnam, 530017, Andhra Pradesh, India.
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Metagenomic insights into the microbial diversity in manganese-contaminated mine tailings and their role in biogeochemical cycling of manganese. Sci Rep 2018; 8:8257. [PMID: 29844399 PMCID: PMC5974364 DOI: 10.1038/s41598-018-26311-w] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 05/08/2018] [Indexed: 11/08/2022] Open
Abstract
To extend the knowledge on the microbial diversity of manganese rich environments, we performed a clone library based study using metagenomic approach. Pyrosequencing based analysis of 16S rRNA genes were carried out on an Illumina platform to gain insights into the bacterial community inhabiting in a manganese mining site and the taxonomic profiles were correlated with the inherent capacities of these strains to solubilise manganese. The application of shot gun sequencing in this study yielded results which revealed the highest prevalence of Proteobacteria (42.47%), followed by Actinobacteria (23.99%) in the area of study. Cluster of orthologous group (COG) functional category has 85,066 predicted functions. Out of which 11% are involved in metabolism of amino acid, 9% are involved in production and conversion of energy while Keto Encyclopedia of Gene and Genomes (KEGG) functional category has 107,388 predicted functions, out of which 55% are involved in cellular metabolism, 15% are environmental and information processing and 12% are genetic information processing in nature. The isolated microbial consortia demonstrated visible growth in presence of high concentrations of Mn. Solubilisation studies resulted in 86% of manganese recovery after 20 days. The result presented in this study has important implications in understanding the microbial diversity in manganese contaminated mine tailings and their role in natural geochemical cycling of Mn.
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Li XY, Xiao N, Zhang YH. Toxic effects of octylphenol on the expression of genes in liver identified by suppression subtractive hybridization of Rana chensinensis. ECOTOXICOLOGY (LONDON, ENGLAND) 2014; 23:1-10. [PMID: 24158398 DOI: 10.1007/s10646-013-1144-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/11/2013] [Indexed: 06/02/2023]
Abstract
Octylphenol (OP) is the degradative product of alkylphenol ethoxylates that are widely used to produce rubber, pesticides, and paints. It is chemically stable substance and demonstrates estrogenic effects, toxicity and carcinogenic effects in the environment. The toxin accumulates rapidly in the liver where it exerts most of its damage, but the molecular mechanisms behind its toxicity remain unclear. Due to limited information concerning the effect of OP on liver, this study investigates how OP causes hepatotoxicity in liver. Here, suppression subtractive hybridization was used to identify the alterations in gene transcription of the frog (Rana chensinensis) after exposure to OP. After hybridization and cloning, the subtractive cDNA libraries were obtained. At random, 207 positive clones were selected and sequenced from the subtractive libraries, which gave a total of 75 gene fragment sequences. The screening identified numerous genes involved in apoptosis, signal transduction, cytoskeletal remodeling, innate immunity, material and energy metabolism, translation and transcription which were extensively discussed. Two sequenced genes were analyzed further using real time quantitative PCR. The two genes from the library were found to be transcriptionally up-regulated. These results confirmed the successful construction of the subtractive cDNA library that was enriched for the genes that were differentially transcribed in the amphibian liver challenged with OP, and for the first time present the basic data on toxicity effect of OP on liver.
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Affiliation(s)
- Xin-Yi Li
- College of Life Science, Shaanxi Normal University, Xi'an, 710062, Shaanxi, China
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Sujith PP, Mourya BS, Krishnamurthi S, Meena RM, Loka Bharathi PA. Mobilization of manganese by basalt associated Mn(II)-oxidizing bacteria from the Indian Ridge System. CHEMOSPHERE 2014; 95:486-495. [PMID: 24183631 DOI: 10.1016/j.chemosphere.2013.09.103] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 09/18/2013] [Accepted: 09/26/2013] [Indexed: 06/02/2023]
Abstract
The Indian Ridge System basalt bearing Mn-oxide coatings had todorokite as the major and birnesite as the minor mineral. We posit that microorganisms associated with these basalts participate in the oxidation of Mn and contribute to mineral deposition. We also hypothesized that, the Mn-oxidizing microbes may respond reversibly to pulses of fresh organic carbon introduced into the water column by mobilizing the Mn in Mn-oxides. To test these two hypotheses, we enumerated the number of Mn-oxidizers and -reducers and carried out studies on the mobilization of Mn by microbial communities associated with basalt. In medium containing 100 μM Mn(2+), 10(3) colony forming units (CFU) were recovered with undetectable number of reducers on Mn-oxide amended medium, suggesting that the community was more oxidative. Experiments were then conducted with basalt fragments at 4±2 °C in the presence 'G(+)' and absence 'G(-)' of glucose (0.1%). Controls included set-ups, some of which were poisoned with 15 mM azide and the others of which were heat-killed. The mobilization of Mn in the presence of glucose was 1.76 μg g(-1) d(-1) and in the absence, it was 0.17 μg g(-1) d(-1) after 150 d. Mn mobilization with and without added glucose was 13 and 4 times greater than the corresponding azide treated controls. However, rates in 'G(+)' were 16 times and 'G(-)' 24 times more than the respective heat killed controls. The corresponding total counts in the presence of added glucose increased from 1.63×10(6) to 6.71×10(7) cells g(-1) and from 1.41×10(7) to 3.52×10(7) cells g(-1) in its absence. Thus, the addition of glucose as a proxy for organic carbon changed the community's response from Mn(II)-oxidizing to Mn(IV)-reducing activity. The results confirm the participation of Mn oxidizing bacteria in the mobilization of Mn. Identification of culturable bacteria by 16S rRNA gene analysis showed taxonomic affiliations to Bacillus, Exiguobacterium, Staphylococcus, Brevibacterium and Alcanivorax sp.
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Affiliation(s)
- P P Sujith
- Microbiology Laboratory, National Institute of Oceanography, Council of Scientific and Industrial Research, Dona Paula 403 004, Goa, India
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Su J, Bao P, Bai T, Deng L, Wu H, Liu F, He J. CotA, a multicopper oxidase from Bacillus pumilus WH4, exhibits manganese-oxidase activity. PLoS One 2013; 8:e60573. [PMID: 23577125 PMCID: PMC3618234 DOI: 10.1371/journal.pone.0060573] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Accepted: 02/28/2013] [Indexed: 11/19/2022] Open
Abstract
Multicopper oxidases (MCOs) are a family of enzymes that use copper ions as cofactors to oxidize various substrates. Previous research has demonstrated that several MCOs such as MnxG, MofA and MoxA can act as putative Mn(II) oxidases. Meanwhile, the endospore coat protein CotA from Bacillus species has been confirmed as a typical MCO. To study the relationship between CotA and the Mn(II) oxidation, the cotA gene from a highly active Mn(II)-oxidizing strain Bacillus pumilus WH4 was cloned and overexpressed in Escherichia coli strain M15. The purified CotA contained approximately four copper atoms per molecule and showed spectroscopic properties typical of blue copper oxidases. Importantly, apart from the laccase activities, the CotA also displayed substantial Mn(II)-oxidase activities both in liquid culture system and native polyacrylamide gel electrophoresis. The optimum Mn(II) oxidase activity was obtained at 53°C in HEPES buffer (pH 8.0) supplemented with 0.8 mM CuCl2. Besides, the addition of o-phenanthroline and EDTA both led to a complete suppression of Mn(II)-oxidizing activity. The specific activity of purified CotA towards Mn(II) was 0.27 U/mg. The Km, Vmax and kcat values towards Mn(II) were 14.85±1.17 mM, 3.01×10(-6)±0.21 M·min(-1) and 0.32±0.02 s(-1), respectively. Moreover, the Mn(II)-oxidizing activity of the recombinant E. coli strain M15-pQE-cotA was significantly increased when cultured both in Mn-containing K liquid medium and on agar plates. After 7-day liquid cultivation, M15-pQE-cotA resulted in 18.2% removal of Mn(II) from the medium. Furthermore, the biogenic Mn oxides were clearly observed on the cell surfaces of M15-pQE-cotA by scanning electron microscopy. To our knowledge, this is the first report that provides the direct observation of Mn(II) oxidation with the heterologously expressed protein CotA, Therefore, this novel finding not only establishes the foundation for in-depth study of Mn(II) oxidation mechanisms, but also offers a potential biocatalyst for Mn(II) removal.
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Affiliation(s)
- Jianmei Su
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, People’s Republic of China
| | - Peng Bao
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, People’s Republic of China
| | - Tenglong Bai
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, People’s Republic of China
| | - Lin Deng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, People’s Republic of China
| | - Hui Wu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, People’s Republic of China
| | - Fan Liu
- Key Laboratory of Arable Land Conservation, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, Hubei, People’s Republic of China
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, People’s Republic of China
- * E-mail:
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