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Chen X, Yu T, Xiao L, Zeng XC. Can Sb(III)-oxidizing prokaryote also oxidize As(III) under aerobic and anaerobic conditions, and vice versa? JOURNAL OF HAZARDOUS MATERIALS 2024; 470:134135. [PMID: 38574656 DOI: 10.1016/j.jhazmat.2024.134135] [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: 10/21/2023] [Revised: 03/03/2024] [Accepted: 03/24/2024] [Indexed: 04/06/2024]
Abstract
Sb(III) and As(III) share similar chemical features and coexist in the environment. However, their oxidase enzymes have completely different sequences and structures. This raises an intriguing question: Could Sb(III)-oxidizing prokaryotes (SOPs) also oxidize As(III), and vice versa? Regarding this issue, previous investigations have yielded unclear, incorrect and even conflicting data. This work aims to address this matter. First, we prepared an enriched population of SOPs that comprises 55 different AnoA genes, lacking AioAB and ArxAB genes. We found that these SOPs can oxidize both Sb(III) and As(III) with comparable capabilities. To further confirm this finding, we isolated three cultivable SOP strains that have AnoA gene, but lack AioAB and ArxAB genes. We observed that they also oxidize both Sb(III) and As(III) under both anaerobic and aerobic conditions. Secondly, we obtained an enriched population of As(III)-oxidizing prokaryotes (AOPs) from As-contaminated soils, which comprises 69 different AioA genes, lacking AnoA gene. We observed that the AOP population has significant As(III)-oxidizing activities, but lack detectable Sb(III)-oxidizing activities under both aerobic and anaerobic conditions. Therefore, we convincingly show that SOPs can oxidize As(III), but AOPs cannot oxidize Sb(III). These findings clarify the previous ambiguities, confusion, errors or contradictions regarding how SOPs and AOPs oxidize each other's substrate.
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Affiliation(s)
- Xiaoming Chen
- State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan, China
| | - Tingting Yu
- State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan, China
| | - Linhai Xiao
- State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan, China
| | - Xian-Chun Zeng
- State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan, China.
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Yang L, Yang A, Song L, Cui W, Bian W, Niu A, Xu P, He S, Mei S, Shi X. Formation of Sb 2O 3 microcrystals by Rhodotorula mucilaginosa. JOURNAL OF HAZARDOUS MATERIALS 2024; 469:134082. [PMID: 38522209 DOI: 10.1016/j.jhazmat.2024.134082] [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: 01/03/2024] [Revised: 03/17/2024] [Accepted: 03/18/2024] [Indexed: 03/26/2024]
Abstract
Antimony (Sb) pollution seriously endangers ecological environment and human health. Microbial induced mineralization can effectively convert metal ions into more stable and less soluble crystalline minerals by extracellular polymeric substance (EPS). In this study, an efficient Sb-resistant Rhodotorula mucilaginosa (R. mucilaginosa) was screened, which can resist 41 mM Sb(III) and directly transform Sb(III) into Sb2O3 microcrystals by EPS. The removal efficiency of R. mucilaginosa for 22 mM Sb(III) reached 70% by converting Sb(III) to Sb2O3. The components of supernatants as well as the effects of supernatants and pH on Sb(III) mineralization verified that inducible and non-inducible extracellular protein/polysaccharide biomacromolecules play important roles in the morphologies and sizes control of Sb2O3 formed by R. mucilaginosa respectively. Sb2O3 microcrystals with different morphologies and sizes can be prepared by the regulation of inducible and non-inducible extracellular biomacromolecules secreted by R. mucilaginosa. This is the first time to identify that R. mucilaginosa can remove Sb(III) by transforming Sb(III) into Sb2O3 microcrystals under the control of EPS. This study contributes to our understanding for Sb(III) biomineralization mechanisms and provides strategies for the remediation of Sb-contaminated environment.
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Affiliation(s)
- Linping Yang
- College of Resources and Environmental Engineering, Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China
| | - Aijiang Yang
- College of Resources and Environmental Engineering, Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China
| | - Liyan Song
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China
| | - Wen Cui
- College of Resources and Environmental Engineering, Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China
| | - Wanping Bian
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
| | - Aping Niu
- College of Resources and Environmental Engineering, Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China.
| | - Peng Xu
- College of Resources and Environmental Engineering, Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China
| | - Shouyang He
- College of Resources and Environmental Engineering, Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China
| | - Shixue Mei
- College of Resources and Environmental Engineering, Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China
| | - Xianrong Shi
- College of Resources and Environmental Engineering, Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China
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Li M, Wang W, Wu M, Lei J, Lu X, Wang H. Stibnite dissolution and Sb oxidation by Paraccocus versutus XT0.6 via direct and indirect contact. JOURNAL OF HAZARDOUS MATERIALS 2024; 467:133731. [PMID: 38340562 DOI: 10.1016/j.jhazmat.2024.133731] [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: 10/02/2023] [Revised: 01/10/2024] [Accepted: 02/04/2024] [Indexed: 02/12/2024]
Abstract
In this study Paraccocus versutus XT0.6 was employed to address the mechanism of microbial dissolution and oxidation of stibnite. Results showed that with the growth of XT0.6, pH increased to 9.0 in both microbe-mineral contact (MM) and microbe-mineral non-contact groups (M[M]). Dissolved Sb(III) was released from stibnite, which was subsequently quickly oxidized to Sb(V) completely in MM and partially in M[M] groups. On the contrast, the final pH decreased to 6.5 and 4.9, respectviely, in system amended with extracellular secretion (EM) of XT0.6 and abiotic groups. Dissolution of stibnite and oxidation of Sb(III) were also observed in EM group, suggesting a potential contribution of extracellular enzyme in Sb(III) oxidation. The dissolution and oxidation rates were the highest in MM group, followed by those in M[M], EM and abiotic groups. To be noted, Sb(V) concentration decreased in MM group on the fifth day, which might indicate the formation of Sb(V)-bearing secondary mineral. Genome of XT0.6 consisted of two chromosomes and one plasmid, and most genes responsible for antimony oxidation and antimony resistance were located on the chromosomes. Proteomics analysis of the extracellular secretions indicated the up-regulated proteins were mainly related to electron-transfer, suggesting their potential role in Sb(III) oxidation.
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Affiliation(s)
- Min Li
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China
| | - Weiqi Wang
- State key Laboratory of Biogeology and Environmental Geology, China
| | - Mengxiaojun Wu
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China
| | - Jingwen Lei
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China
| | - Xiaolu Lu
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China
| | - Hongmei Wang
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China; State key Laboratory of Biogeology and Environmental Geology, China.
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Loni PC, Wang W, Qiu X, Man B, Wu M, Qiu D, Wang H. Antimony precipitation and removal by antimony hyper resistant strain Achromobacter sp. 25-M. ENVIRONMENTAL RESEARCH 2024; 245:118011. [PMID: 38141916 DOI: 10.1016/j.envres.2023.118011] [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: 09/09/2023] [Revised: 11/13/2023] [Accepted: 12/21/2023] [Indexed: 12/25/2023]
Abstract
Microbes have been confirmed to play key role in biogeochemistry of antimony. However, the impact of indigenous bacteria (from active mines) on the behavior of dissolved antimony remained poorly understood. In current study, the hyper antimony-resistant strain, Achromobacter sp. 25-M, isolated from the world largest antimony deposit, Xikuangshan antimony deposit, was evaluated for its role in dissolved Sb(V) and Sb(III) precipitation and removal. Despite of the high resistance to Sb(III) (up to 50 mM), the facultative alkaliphile, 25-M was not capable of Sb(III) oxidation. Meanwhile 25-M can produce high amount of exopolymeric substance (EPS) with the presence of Sb, which prompted us to investigate the potential role of EPS in the precipitation and removal of Sb. To this end, 2 mM of Sb(III) and Sb(V) were added into the experimental systems with and without 25-M to discern the interaction mechanism between microbe and antimony. After 96 hrs' incubation, 88% [1.73 mM (210 mg/L)] of dissolved Sb(V) and 80% [1.57 mM (190 mg/L)] of dissolved Sb(III) were removed. X-ray diffraction and energy dispersive spectroscopy analysis confirmed the formation of valentinite (Sb2O3) in Sb(III) amended system and a solitary Sb(V) mineral mopungite [NaSb(OH)6] in Sb(V) amended group with microbes. Conversely, no precipitate was detected in abiotic systems. Morphologically valentinite was bowtie and mopungite was pseudo-cubic as indicated by scanning electronic microscopy. EPS was subjected to fourier transform infrared (FT-IR) analysis. FT-IR analysis suggested that -OH and -COO groups were responsible for the complexation and ligand exchange with Sb(III) and Sb(V), respectively. Additionally, the C-H group and N-H group could be involved in π-π interaction and chelation with Sb species. All these interactions between Sb and functional groups in EPS may subsequently favore the formation of valentinite and mopungite. Collectively, current results suggested that EPS play fundamental role in bioprecipitation of Sb, which offered a new strategy in Sb bioremediation.
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Affiliation(s)
- Prakash C Loni
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, China; School of Environmental Studies, China University of Geosciences, Wuhan, 430078, China; Department of Earth Sciences, National Cheng Kung University, Tainan, 701, Taiwan
| | - Weiqi Wang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, China; School of Environmental Studies, China University of Geosciences, Wuhan, 430078, China
| | - Xuan Qiu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, China; School of Environmental Studies, China University of Geosciences, Wuhan, 430078, China
| | - Baiying Man
- College of Life Science, Shangrao Normal University, Shangrao, 334001, China
| | - Mengxiaojun Wu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, China; School of Environmental Studies, China University of Geosciences, Wuhan, 430078, China; Zhejiang Economic and Information Center, Hangzhou, 310006, China
| | - Dongru Qiu
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430074, China
| | - Hongmei Wang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, China; School of Environmental Studies, China University of Geosciences, Wuhan, 430078, China.
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Seridou P, Fyntrilakis K, Kyritsi S, Syranidou E, Kalogerakis N. Effect of endophytic bacteria on the phytoremediation potential of halophyte Tamarix smyrnensis for Sb-contaminated soils. INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2023; 26:964-974. [PMID: 38038643 DOI: 10.1080/15226514.2023.2288144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
Phytoremediation, including bacteria-assisted phytoremediation, presents a promising technology for treating shooting range soils contaminated with toxic metalloids. In this study, a pot experiment was performed using the halophyte Tamarix smyrnensis and soil collected from a shooting range and artificially spiked at two different antimonite (Sb(III)) concentrations (50 mg/kg and 250 mg/kg) with the aim to explore the Sb phytoremediation of the halophyte. The effect of salt (0.3%) and Mn addition (300 ppm) on its remediation capacity was also investigated. Moreover, the root endophytic community of the halophyte was found able to remove Sb(III) and was periodically inoculated to the plants. The consortium application increased the Sb bioavailable fraction in the soil and enhanced the Sb accumulation in root and aerial parts (up to 50% and 55% respectively at high Sb(III) concentration) compared to the uninoculated plants. Moreover, the presence of Mn increased the translocation factor (21% increase for inoculated and 46% increase for uninoculated plants) while lower TF was observed at high Sb concentrations (0,2 and 0,07 was the lowest value at low and high Sb treatments respectively). The addition of salt, Mn and root endophytic bacteria aided the halophyte to cope with elevated Sb concentrations. The total chlorophyll concentration was higher in inoculated plants compared to the uninoculated ones in all treatments, implying the positive effects of endophytic inoculation. The halophyte T. smyrnensis with the aid of endophytic community presents a promising alternative for remediating shooting range soils especially in areas impacted by salinity.
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Affiliation(s)
- Petroula Seridou
- School of Chemical and Environmental Engineering, Technical University of Crete, Chania, Greece
| | | | - Sofia Kyritsi
- School of Chemical and Environmental Engineering, Technical University of Crete, Chania, Greece
| | - Evdokia Syranidou
- School of Chemical and Environmental Engineering, Technical University of Crete, Chania, Greece
| | - Nicolas Kalogerakis
- School of Chemical and Environmental Engineering, Technical University of Crete, Chania, Greece
- Institute of Geoenergy, Foundation for Research and Technology - Hellas (FORTH), Chania, Greece
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Yang J, Zhao D, Liu T, Zhang S, Wang W, Yan L, Gu JD. Growth and genome-based insights of Fe(III) reduction of the high-temperature and NaCl-tolerant Shewanella xiamenensis from Changqing oilfield of China. Front Microbiol 2022; 13:1028030. [PMID: 36545192 PMCID: PMC9760863 DOI: 10.3389/fmicb.2022.1028030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 11/17/2022] [Indexed: 12/09/2022] Open
Abstract
Introduction A facultative anaerobe bacterium Shewanella xiamenensis CQ-Y1 was isolated from the wastewater of Changqing oilfield in Shaanxi Province of China. Shewanella is the important dissimilatory metal-reducing bacteria. It exhibited a well potential application in biodegradation and bioremediation. Methods Genome sequencing, assembling and functional annotation were conducted to explore the genome information of CQ-Y1. The effect of temperatures and NaCl concentrations on the CQ-Y1 growth and Fe(III) reduction were investigated by UV visible spectrophotometry, SEM and XRD. Results Genomic analysis revealed its complete genome was a circular chromosome of 4,710,887 bp with a GC content of 46.50% and 4,110 CDSs genes, 86 tRNAs and 26 rRNAs. It contains genes encoding for Na+/H+ antiporter, K+/Cl- transporter, heat shock protein associated with NaCl and high-temperature resistance. The presence of genes related to flavin, Cytochrome c, siderophore, and other related proteins supported Fe(III) reduction. In addition, CQ-Y1 could survive at 10% NaCl (w/v) and 45°C, and temperature showed more pronounced effects than NaCl concentration on the bacterial growth. The maximum Fe(III) reduction ratio of CQ-Y1 reached 70.1% at 30°C without NaCl, and the reduction reaction remained active at 40°C with 3% NaCl (w/v). NaCl concentration was more effective than temperature on microbial Fe(III) reduction. And the reduction products under high temperature and high NaCl conditions were characterized as Fe3(PO4)2, FeCl2 and Fe(OH)2. Discussion Accordingly, a Fe(III) reduction mechanism of CQ-Y1 mediated by Cytochrome c and flavin was hypothesised. These findings could provide information for a better understanding of the origin and evolution of genomic and metabolic diversity of S. xiamenensis.
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Affiliation(s)
- Jiani Yang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Dan Zhao
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Tao Liu
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, China,Key Laboratory of Low-Carbon Green Agriculture in Northeastern China, Ministry of Agriculture and Rural Affairs, Daqing, China
| | - Shuang Zhang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Weidong Wang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, China,Key Laboratory of Low-Carbon Green Agriculture in Northeastern China, Ministry of Agriculture and Rural Affairs, Daqing, China
| | - Lei Yan
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, China,*Correspondence: Lei Yan,
| | - Ji-Dong Gu
- Environmental Science and Engineering Research Group, Guangdong Technion – Israel Institute of Technology, Shantou, Guangdong, China,Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion, Guangdong Technion – Israel Institute of Technology, Shantou, Guangdong, China
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Liang T, Li D, Zunong J, Li M, Amaerjiang N, Xiao H, Khattab NM, Vermund SH, Hu Y. Interplay of Lymphocytes with the Intestinal Microbiota in Children with Nonalcoholic Fatty Liver Disease. Nutrients 2022; 14:nu14214641. [PMID: 36364902 PMCID: PMC9657134 DOI: 10.3390/nu14214641] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 10/24/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022] Open
Abstract
Abnormally high lymphocyte counts are seen in persons with nonalcoholic fatty liver disease (NAFLD). Gut microbiota dysbiosis is a risk factor for NAFLD. We assessed the gut microbiota of 63 healthy children and 63 children with NAFLD using 16S rRNA gene and metagenomic sequencing to explore the relationships. Compared with healthy children (HC group), the Bacteroidetes, Verrucomicrobia, and Akkermansia were less abundant, while the Actinobacteria were more abundant in children with NAFLD (FLD group). To understand the effect of lymphocytes on the gut microbiota of children with NAFLD, we compared the microbiota of 41 children with NAFLD and high numbers of lymphocytes (FLD_HL group) and 22 children with NAFLD and low numbers of lymphocytes (FLD_LL group). The abundances of Bacteroidetes, Verrucobacterium, and Akkermansia increased and Actinobacteria decreased in the FLD_LL group compared to the FLD_HL group. Akkermansia was negatively correlated with lymphocyte count. NAFLD may disturb the gut microbiota in children through reducing the abundance of Akkermansia and increasing the abundance of proinflammatory bacteria, such as Escherichia-Shigella. Conclusions: High lymphocyte counts are associated with disturbances of gut microbiota and emergence of opportunistic pathogens in children with NAFLD.
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Affiliation(s)
- Tian Liang
- Department of Child, Adolescent Health and Maternal Care, School of Public Health, Capital Medical University, Beijing 100069, China
| | - Dan Li
- Yale School of Public Health, Yale University, New Haven, CT 06510-3201, USA
| | - Jiawulan Zunong
- Department of Child, Adolescent Health and Maternal Care, School of Public Health, Capital Medical University, Beijing 100069, China
| | - Menglong Li
- Department of Child, Adolescent Health and Maternal Care, School of Public Health, Capital Medical University, Beijing 100069, China
| | - Nubiya Amaerjiang
- Department of Child, Adolescent Health and Maternal Care, School of Public Health, Capital Medical University, Beijing 100069, China
| | - Huidi Xiao
- Department of Child, Adolescent Health and Maternal Care, School of Public Health, Capital Medical University, Beijing 100069, China
| | - Nourhan M. Khattab
- Department of Child, Adolescent Health and Maternal Care, School of Public Health, Capital Medical University, Beijing 100069, China
| | - Sten H. Vermund
- Yale School of Public Health, Yale University, New Haven, CT 06510-3201, USA
| | - Yifei Hu
- Department of Child, Adolescent Health and Maternal Care, School of Public Health, Capital Medical University, Beijing 100069, China
- Correspondence: or ; Tel.: +86-10-83911747
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Characterization of Two Highly Arsenic-Resistant Caulobacteraceae Strains of Brevundimonas nasdae: Discovery of a New Arsenic Resistance Determinant. Int J Mol Sci 2022; 23:ijms23105619. [PMID: 35628430 PMCID: PMC9144182 DOI: 10.3390/ijms23105619] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/12/2022] [Accepted: 05/13/2022] [Indexed: 02/07/2023] Open
Abstract
Arsenic (As), distributed widely in the natural environment, is a toxic substance which can severely impair the normal functions in living cells. Research on the genetic determinants conferring functions in arsenic resistance and metabolism is of great importance for remediating arsenic-contaminated environments. Many organisms, including bacteria, have developed various strategies to tolerate arsenic, by either detoxifying this harmful element or utilizing it for energy generation. More and more new arsenic resistance (ars) determinants have been identified to be conferring resistance to diverse arsenic compounds and encoded in ars operons. There is a hazard in mobilizing arsenic during gold-mining activities due to gold- and arsenic-bearing minerals coexisting. In this study, we isolated 8 gold enrichment strains from the Zijin gold and copper mine (Longyan, Fujian Province, China) wastewater treatment site soil, at an altitude of 192 m. We identified two Brevundimonas nasdae strains, Au-Bre29 and Au-Bre30, among these eight strains, having a high minimum inhibitory concentration (MIC) for As(III). These two strains contained the same ars operons but displayed differences regarding secretion of extra-polymeric substances (EPS) upon arsenite (As(III)) stress. B. nasdae Au-Bre29 contained one extra plasmid but without harboring any additional ars genes compared to B. nasdae Au-Bre30. We optimized the growth conditions for strains Au-Bre29 and Au-Bre30. Au-Bre30 was able to tolerate both a lower pH and slightly higher concentrations of NaCl. We also identified folE, a folate synthesis gene, in the ars operon of these two strains. In most organisms, folate synthesis begins with a FolE (GTP-Cyclohydrolase I)-type enzyme, and the corresponding gene is typically designated folE (in bacteria) or gch1 (in mammals). Heterologous expression of folE, cloned from B. nasdae Au-Bre30, in the arsenic-hypersensitive strain Escherichia coli AW3110, conferred resistance to As(III), arsenate (As(V)), trivalent roxarsone (Rox(III)), pentavalent roxarsone (Rox(V)), trivalent antimonite (Sb(III)), and pentavalent antimonate (Sb(V)), indicating that folate biosynthesis is a target of arsenite toxicity and increased production of folate confers increased resistance to oxyanions. Genes encoding Acr3 and ArsH were shown to confer resistance to As(III), Rox(III), Sb(III), and Sb(V), and ArsH also conferred resistance to As(V). Acr3 did not confer resistance to As(V) and Rox(V), while ArsH did not confer resistance to Rox(V).
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