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Mohsin H, Shafique M, Zaid M, Rehman Y. Microbial biochemical pathways of arsenic biotransformation and their application for bioremediation. Folia Microbiol (Praha) 2023:10.1007/s12223-023-01068-6. [PMID: 37326815 DOI: 10.1007/s12223-023-01068-6] [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: 12/17/2022] [Accepted: 05/19/2023] [Indexed: 06/17/2023]
Abstract
Arsenic is a ubiquitous toxic metalloid, the concentration of which is beyond WHO safe drinking water standards in many areas of the world, owing to many natural and anthropogenic activities. Long-term exposure to arsenic proves lethal for plants, humans, animals, and even microbial communities in the environment. Various sustainable strategies have been developed to mitigate the harmful effects of arsenic which include several chemical and physical methods, however, bioremediation has proved to be an eco-friendly and inexpensive technique with promising results. Many microbes and plant species are known for arsenic biotransformation and detoxification. Arsenic bioremediation involves different pathways such as uptake, accumulation, reduction, oxidation, methylation, and demethylation. Each of these pathways has a certain set of genes and proteins to carry out the mechanism of arsenic biotransformation. Based on these mechanisms, various studies have been conducted for arsenic detoxification and removal. Genes specific for these pathways have also been cloned in several microorganisms to enhance arsenic bioremediation. This review discusses different biochemical pathways and the associated genes which play important roles in arsenic redox reactions, resistance, methylation/demethylation, and accumulation. Based on these mechanisms, new methods can be developed for effective arsenic bioremediation.
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Affiliation(s)
- Hareem Mohsin
- Department of Life Sciences, School of Science, University of Management and Technology, Lahore, Pakistan
| | - Maria Shafique
- Institute of Microbiology and Molecular Genetics, University of the Punjab, Quaid-e-Azam Campus, Lahore, Pakistan
| | - Muhammad Zaid
- Department of Life Sciences, School of Science, University of Management and Technology, Lahore, Pakistan
| | - Yasir Rehman
- Department of Life Sciences, School of Science, University of Management and Technology, Lahore, Pakistan.
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2
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Larson J, Tokmina-Lukaszewska M, Fausset H, Spurzem S, Cox S, Cooper G, Copié V, Bothner B. Arsenic Exposure Causes Global Changes in the Metalloproteome of Escherichia coli. Microorganisms 2023; 11:382. [PMID: 36838347 PMCID: PMC9965246 DOI: 10.3390/microorganisms11020382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/03/2023] [Accepted: 02/01/2023] [Indexed: 02/05/2023] Open
Abstract
Arsenic is a toxic metalloid with differential biological effects, depending on speciation and concentration. Trivalent arsenic (arsenite, AsIII) is more toxic at lower concentrations than the pentavalent form (arsenate, AsV). In E. coli, the proteins encoded by the arsRBC operon are the major arsenic detoxification mechanism. Our previous transcriptional analyses indicate broad changes in metal uptake and regulation upon arsenic exposure. Currently, it is not known how arsenic exposure impacts the cellular distribution of other metals. This study examines the metalloproteome of E. coli strains with and without the arsRBC operon in response to sublethal doses of AsIII and AsV. Size exclusion chromatography coupled with inductively coupled plasma mass spectrometry (SEC-ICPMS) was used to investigate the distribution of five metals (56Fe, 24Mg, 66Zn, 75As, and 63Cu) in proteins and protein complexes under native conditions. Parallel analysis by SEC-UV-Vis spectroscopy monitored the presence of protein cofactors. Together, these data reveal global changes in the metalloproteome, proteome, protein cofactors, and soluble intracellular metal pools in response to arsenic stress in E. coli. This work brings to light one outcome of metal exposure and suggests that metal toxicity on the cellular level arises from direct and indirect effects.
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Affiliation(s)
| | | | | | | | | | | | | | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59715, USA
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3
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Ke T, Zhang D, Guo H, Xiu W, Zhao Y. Geogenic arsenic and arsenotrophic microbiome in groundwater from the Hetao Basin. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 852:158549. [PMID: 36075436 DOI: 10.1016/j.scitotenv.2022.158549] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 08/28/2022] [Accepted: 09/01/2022] [Indexed: 06/15/2023]
Abstract
High arsenic (As) in groundwater is an environmental issue of global concern, which is closely related to microbe-mediated As biogeochemical cycling. However, the distribution of genes related to As cycling and underlying microbial As biogeochemical processes in high As groundwater remain elusive. Hence, we profiled the As cycling genes (arsC, arrA, and aioA genes) and indigenous microbial communities in groundwater from a typical high As area, the Hetao Basin from China, using amplicon sequencing and qPCR techniques. Here, we revealed the significant difference in microbial community structure between low As groundwater samples (LG) and high As groundwater samples (HG). Acinetobacter, Thiovirga, Hydrogenophaga, and Sulfurimonas were dominant in LG, while Aquabcterium, Acinetobacter, Sphingomonas, Pseudomonas, Desulfomicrobium, Hydrogenophaga, and Nitrospira were predominant in HG. Shannon and Chao indices of the microbial communities in HG were significantly higher than those of in LG. Alpha diversity and abundance of arsC and arrA genes were higher than those of aioA genes. The significant positive correlation was uncovered between the abundances of arsC and aioA genes, suggesting the cooccurrence of As functional genes in groundwater. Sphingopyxis, Agrobacterium, Klebsiella, Hoeflea, and Aeromonas represented the dominant taxa within the As (V) reducers communities. Distance-based redundancy analysis showed that ORP, pH, Astot, Mn, and DOC were the key factors shaping the diverse microbial populations, while ORP, S2-, As(III), Fe(II), NH4+, pH, Mn, SO42-, As(V), temperature, and P as the main drivers affecting arsenotrophic microbiota. This work provides an insight into microbial communities linked to As biogeochemical processes in high As groundwater, playing a fundamental role in groundwater As cycling.
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Affiliation(s)
- Tiantian Ke
- Ministry of Education, Key Laboratory of Groundwater Circulation and Environmental Evolution, School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Beijing), Beijing, China
| | - Di Zhang
- Ministry of Education, Key Laboratory of Groundwater Circulation and Environmental Evolution, School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Beijing), Beijing, China
| | - Huaming Guo
- Ministry of Education, Key Laboratory of Groundwater Circulation and Environmental Evolution, School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Beijing), Beijing, China.
| | - Wei Xiu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Beijing), Beijing, China
| | - Yi Zhao
- Ministry of Education, Key Laboratory of Groundwater Circulation and Environmental Evolution, School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, China
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Arsenic Accumulation and Biotransformation Affected by Nutrients (N and P) in Common Blooming-Forming Microcystis wesenbergii (Komárek) Komárek ex Komárek (Cyanobacteria). WATER 2022. [DOI: 10.3390/w14020245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Arsenic accumulation and biotransformation in algae was mostly carried out in a medium that contained far higher nutrient concentrations than that in natural freshwaters. The obtained results might have limited environmental validity and result in a failure to describe authentic arsenic biogeochemical cycles in natural freshwater systems. To validate the assumption, arsenic accumulation, and biotransformation in common bloom forming Microcystis wesenbergii was performed under a high nutrient concentration in BG11 medium (N = 250 mg/L, P = 7.13 mg/L), and adjusted low nutrients that mimicked values in natural freshwaters (N = 1.5 mg/L, P = 0.3 mg/L). The growth rate and maximum M. wesenbergii cell density were much lower in the high nutrient set, but more inhibition was shown with increasing ambient iAs(V) concentrations both in the high and low nutrient sets. The proportion of intracellular contents in total arsenicals decreased with increasing iAs(V) concentrations in both high and low nutrient sets but increased with incubation time. Intracellular iAs(III) was not found in the high nutrient set, while it formed high concentrations that could be comparable to that of an extracellular level in the low nutrient set. M. wesenbergii could methylate arsenic, and a higher proportion of organoarsenicals was formed in the low nutrient set. Lower intracellular MMA(V) and DMA(V) concentrations were found in the high nutrient set; contrarily, they presented a higher concentration that could be comparable to the extracellular ones in the low nutrient set. The results demonstrated that different nutrient regimes could affect arsenic accumulation and biotransformation in M. wesenbergii, and low nutrient concentrations could inhibit the excretion of iAs(III), MMA(V) and DMA(V) out of cells. Further investigations should be based on natural freshwater systems to obtain an authentic arsenic accumulation and biotransformation in cyanobacteria.
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Rawle R, Saley TC, Kang YS, Wang Q, Walk S, Bothner B, McDermott TR. Introducing the ArsR-Regulated Arsenic Stimulon. Front Microbiol 2021; 12:630562. [PMID: 33746923 PMCID: PMC7965956 DOI: 10.3389/fmicb.2021.630562] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/18/2021] [Indexed: 12/21/2022] Open
Abstract
The microbial ars operon encodes the primary bacterial defense response to the environmental toxicant, arsenic. An important component of this operon is the arsR gene, which encodes ArsR, a member of the family of proteins categorized as DNA-binding transcriptional repressors. As currently documented, ArsR regulates its own expression as well as other genes in the same ars operon. This study examined the roles of four ArsR proteins in the well-developed model Gram-negative bacterium Agrobacterium tumefaciens 5A. RNASeq was used to compare and characterize gene expression profiles in ± arsenite-treated cells of the wild-type strain and in four different arsR mutants. We report that ArsR-controlled transcription regulation is truly global, extending well beyond the current ars operon model, and includes both repression as well as apparent activation effects. Many cellular functions are significantly influenced, including arsenic resistance, phosphate acquisition/metabolism, sugar transport, chemotaxis, copper tolerance, iron homeostasis, and many others. While there is evidence of some regulatory overlap, each ArsR exhibits its own regulatory profile. Furthermore, evidence of a regulatory hierarchy was observed; i.e. ArsR1 represses arsR4, ArsR4 activates arsR2, and ArsR2 represses arsR3. Additionally and unexpectedly, aioB (arsenite oxidase small subunit) expression was shown to be under partial positive control by ArsR2 and ArsR4. Summarizing, this study demonstrates the regulatory portfolio of arsenite-activated ArsR proteins and includes essentially all major cellular functions. The broad bandwidth of arsenic effects on microbial metabolism assists in explaining and understanding the full impact of arsenic in natural ecosystems, including the mammalian gut.
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Affiliation(s)
- Rachel Rawle
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Tara C Saley
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, United States
| | - Yoon-Suk Kang
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, United States
| | - Qian Wang
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, United States
| | - Seth Walk
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
| | - Timothy R McDermott
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, United States
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6
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Xiao E, Cui J, Sun W, Jiang S, Huang M, Kong D, Wu Q, Xiao T, Sun X, Ning Z. Root microbiome assembly of As-hyperaccumulator Pteris vittata and its efficacy in arsenic requisition. Environ Microbiol 2021; 23:1959-1971. [PMID: 33145903 DOI: 10.1111/1462-2920.15299] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 10/25/2020] [Accepted: 10/29/2020] [Indexed: 11/29/2022]
Abstract
The assemblage of root-associated microorganisms plays important roles in improving their capability to adapt to environmental stress. Metal(loid) hyperaccumulators exhibit disparate adaptive capability compared to that of non-hyperaccumulators when faced with elevated contents of metal(loid)s. However, knowledge of the assemblage of root microbes of hyperaccumulators and their ecological roles in plant growth is still scarce. The present study used Pteris vittata as a model plant to study the microbial assemblage and its beneficial role in plant growth. We demonstrated that the assemblage of microbes from the associated bulk soil to the root compartment was based on their lifestyles. We used metagenomic analysis and identified that the assembled microbes were primarily involved in root-microbe interactions in P. vittata root. Notably, we identified that the assembled root microbiome played an important role in As requisition, which promoted the fitness and growth of P. vittata. This study provides new insights into the root microbiome and potential valuable knowledge to understand how the root microbiome contributes to the fitness of its host.
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Affiliation(s)
- Enzong Xiao
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Jinli Cui
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Weimin Sun
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental Science and Technology, Guangzhou, 510650, China
| | - Shiming Jiang
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Mengyan Huang
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Deguan Kong
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Qihang Wu
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Tangfu Xiao
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Xiaoxu Sun
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental Science and Technology, Guangzhou, 510650, China
| | - Zengping Ning
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
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7
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Shi K, Wang Q, Wang G. Microbial Oxidation of Arsenite: Regulation, Chemotaxis, Phosphate Metabolism and Energy Generation. Front Microbiol 2020; 11:569282. [PMID: 33072028 PMCID: PMC7533571 DOI: 10.3389/fmicb.2020.569282] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 08/21/2020] [Indexed: 12/11/2022] Open
Abstract
Arsenic (As) is a metalloid that occurs widely in the environment. The biological oxidation of arsenite [As(III)] to arsenate [As(V)] is considered a strategy to reduce arsenic toxicity and provide energy. In recent years, research interests in microbial As(III) oxidation have been growing, and related new achievements have been revealed. This review focuses on the highlighting of the novel regulatory mechanisms of bacterial As(III) oxidation, the physiological relevance of different arsenic sensing systems and functional relationship between microbial As(III) oxidation and those of chemotaxis, phosphate uptake, carbon metabolism and energy generation. The implication to environmental bioremediation applications of As(III)-oxidizing strains, the knowledge gaps and perspectives are also discussed.
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Affiliation(s)
- Kaixiang Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Qian Wang
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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8
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Rawle RA, Tokmina-Lukaszewska M, Shi Z, Kang YS, Tripet BP, Dang F, Wang G, McDermott TR, Copie V, Bothner B. Metabolic Responses to Arsenite Exposure Regulated through Histidine Kinases PhoR and AioS in Agrobacterium tumefaciens 5A. Microorganisms 2020; 8:microorganisms8091339. [PMID: 32887433 PMCID: PMC7565993 DOI: 10.3390/microorganisms8091339] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/14/2020] [Accepted: 08/27/2020] [Indexed: 11/16/2022] Open
Abstract
Arsenite (AsIII) oxidation is a microbially-catalyzed transformation that directly impacts arsenic toxicity, bioaccumulation, and bioavailability in environmental systems. The genes for AsIII oxidation (aio) encode a periplasmic AsIII sensor AioX, transmembrane histidine kinase AioS, and cognate regulatory partner AioR, which control expression of the AsIII oxidase AioBA. The aio genes are under ultimate control of the phosphate stress response via histidine kinase PhoR. To better understand the cell-wide impacts exerted by these key histidine kinases, we employed 1H nuclear magnetic resonance (1H NMR) and liquid chromatography-coupled mass spectrometry (LC-MS) metabolomics to characterize the metabolic profiles of ΔphoR and ΔaioS mutants of Agrobacterium tumefaciens 5A during AsIII oxidation. The data reveals a smaller group of metabolites impacted by the ΔaioS mutation, including hypoxanthine and various maltose derivatives, while a larger impact is observed for the ΔphoR mutation, influencing betaine, glutamate, and different sugars. The metabolomics data were integrated with previously published transcriptomics analyses to detail pathways perturbed during AsIII oxidation and those modulated by PhoR and/or AioS. The results highlight considerable disruptions in central carbon metabolism in the ΔphoR mutant. These data provide a detailed map of the metabolic impacts of AsIII, PhoR, and/or AioS, and inform current paradigms concerning arsenic-microbe interactions and nutrient cycling in contaminated environments.
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Affiliation(s)
- Rachel A. Rawle
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA;
| | - Monika Tokmina-Lukaszewska
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA; (M.T.-L.); (B.P.T.); (F.D.)
| | - Zunji Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; (Z.S.); (G.W.)
| | - Yoon-Suk Kang
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717, USA; (Y.-S.K.); (T.R.M.)
| | - Brian P. Tripet
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA; (M.T.-L.); (B.P.T.); (F.D.)
| | - Fang Dang
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA; (M.T.-L.); (B.P.T.); (F.D.)
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; (Z.S.); (G.W.)
| | - Timothy R. McDermott
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717, USA; (Y.-S.K.); (T.R.M.)
| | - Valerie Copie
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA; (M.T.-L.); (B.P.T.); (F.D.)
- Correspondence: (V.C.); (B.B.)
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA; (M.T.-L.); (B.P.T.); (F.D.)
- Correspondence: (V.C.); (B.B.)
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9
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Wang J, Xie Z, Wei X, Chen M, Luo Y, Wang Y. An indigenous bacterium Bacillus XZM for phosphate enhanced transformation and migration of arsenate. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 719:137183. [PMID: 32120093 DOI: 10.1016/j.scitotenv.2020.137183] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 01/05/2020] [Accepted: 02/06/2020] [Indexed: 06/10/2023]
Abstract
A number of arsenate-reducing bacteria respire adsorbed As(V), producing As(III) and thus contributing to arsenic mobilization from the solid phase to the aqueous phase. Two arsenate reducing genes, arsC and arrA, were both amplified in an indigenous bacterium Bacillus XZM isolated from high arsenic aquifer sediments. The effect of phosphate input on this novel bacterium in terms of mediating the biogeochemical behavior of arsenic was investigated for the first time. The results show bacterial growth and arsenate reduction appear to increase with the addition of phosphate. Input of 1 mM phosphate reduced the negative effects of As(V) on bacterial growth, resulting in 55-60% greater biomass production compared to lower phosphate inputs (0.01 and 0.1 mM). The data of real-time quantitative PCR (qPCR) indicated arsenate was involved in the expressions of two arsenate reductase genes (arsC and arrA genes) in indigenous bacterium Bacillus XZM. Overall, the addition of phosphate (from 0.1 to 1 mM) resulted in a doubling of arsenate bio-desorption from the sediment into the aqueous medium. Oxidation-reduction potential, as an environmental indicator of the bacterial reduction of metals, declined to -200 mV in the presence of strain XZM and 1 mM phosphate in the microcosm. Phosphate input enhanced arsenic biomigration, indicating the effect of phosphate concentration should be considered when studying the biogeochemical behavior of arsenic.
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Affiliation(s)
- Jia Wang
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China
| | - Zuoming Xie
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, PR China.
| | - Xiaofan Wei
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China
| | - Mengna Chen
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China
| | - Yan Luo
- Environmental Monitoring Station, Jianli Environmental Protection Bureau, Hubei, Jianli 433300, PR China
| | - Yanxin Wang
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, PR China
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10
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McDermott TR, Stolz JF, Oremland RS. Arsenic and the gastrointestinal tract microbiome. ENVIRONMENTAL MICROBIOLOGY REPORTS 2020; 12:136-159. [PMID: 31773890 DOI: 10.1111/1758-2229.12814] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 11/23/2019] [Accepted: 11/25/2019] [Indexed: 06/10/2023]
Abstract
Arsenic is a toxin, ranking first on the Agency for Toxic Substances and Disease Registry and the Environmental Protection Agency Priority List of Hazardous Substances. Chronic exposure increases the risk of a broad range of human illnesses, most notably cancer; however, there is significant variability in arsenic-induced disease among exposed individuals. Human genetics is a known component, but it alone cannot account for the large inter-individual variability in the presentation of arsenicosis symptoms. Each part of the gastrointestinal tract (GIT) may be considered as a unique environment with characteristic pH, oxygen concentration, and microbiome. Given the well-established arsenic redox transformation activities of microorganisms, it is reasonable to imagine how the GIT microbiome composition variability among individuals could play a significant role in determining the fate, mobility and toxicity of arsenic, whether inhaled or ingested. This is a relatively new field of research that would benefit from early dialogue aimed at summarizing what is known and identifying reasonable research targets and concepts. Herein, we strive to initiate this dialogue by reviewing known aspects of microbe-arsenic interactions and placing it in the context of potential for influencing host exposure and health risks. We finish by considering future experimental approaches that might be of value.
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Affiliation(s)
- Timothy R McDermott
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, 59717, USA
| | - John F Stolz
- Department of Biological Sciences and Center for Environmental Research and Education, Duquesne University, Pittsburgh, PA, USA
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11
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Efflux proteins MacAB confer resistance to arsenite and penicillin/macrolide-type antibiotics in Agrobacterium tumefaciens 5A. World J Microbiol Biotechnol 2019; 35:115. [PMID: 31332542 DOI: 10.1007/s11274-019-2689-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 07/07/2019] [Indexed: 10/26/2022]
Abstract
Antibiotic and arsenic (As) contaminations are worldwide public health problems. Previously, the bacterial ABC-type efflux protein MacAB reportedly conferred resistance to macrolide-type antibiotics but not to other metal(loid)s. In this study, the roles of MacAB for the co-resistance of different antibiotics and several metal(loid)s were analyzed in Agrobacterium tumefaciens 5A, a strain resistant to arsenite [As(III)] and several types of antibiotics. The macA and macB genes were cotranscribed, and macB was deleted in A. tumefaciens 5A and heterologously expressed in Escherichia coli AW3110 and E. coli S17-1. Compared to the wild-type strain 5A, the macB deletion strain reduced bacterial resistance levels to several macrolide-type and penicillin-type antibiotics but not to cephalosporin-type antibiotics. In addition, the macB deletion strain showed lower resistance to As(III) but not to arsenate [As(V)], antimonite [Sb(III)] and cadmium chloride [Cd(II)]. The mutant strain 5A-ΔmacB cells accumulated more As(III) than the cells of the wild-type. Furthermore, heterologous expression of MacAB in E. coli S17-1 showed that MacAB was essential for resistance to macrolide, several penicillin-type antibiotics and As(III) but not to As(V). Heterologous expression of MacAB in E. coli AW3110 reduced the cellular accumulation of As(III) but not of As(V), indicating that MacAB is responsible for the efflux of As(III). These results demonstrated that, in addition to macrolide-type antibiotics, MacAB also conferred resistance to penicillin-type antibiotics and As(III) by extruding them out of cells. This finding contributes to a better understanding of the bacterial resistance mechanisms of antibiotics and metal(loid)s.
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12
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Regulation of antimonite oxidation and resistance by the phosphate regulator PhoB in Agrobacterium tumefaciens GW4. Microbiol Res 2019; 226:10-18. [PMID: 31284939 DOI: 10.1016/j.micres.2019.04.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 01/13/2019] [Accepted: 04/24/2019] [Indexed: 11/21/2022]
Abstract
Microbial oxidation of antimonite [Sb(III)] to antimonate [Sb(V)] is a detoxification process which contributes to Sb(III) resistance. Antimonite oxidase AnoA is essential for Sb(III) oxidation, however, the regulation mechanism is still unknown. Recently, we found that the expressions of phosphate transporters were induced by Sb(III) using proteomics analysis in Agrobacterium tumefaciens GW4, thus, we predicted that the phosphate regulator PhoB may regulate bacterial Sb(III) oxidation and resistance. In this study, comprehensive analyses were performed and the results showed that (1) Genomic analysis revealed two phoB (named as phoB1 and phoB2) and one phoR gene in strain GW4; (2) Reporter gene assay showed that both phoB1 and phoB2 were induced in low phosphate condition (50 μM), but only phoB2 was induced by Sb(III); (3) Genes knock-out/complementation, Sb(III) oxidation and Sb(III) resistance tests showed that deletion of phoB2 significantly inhibited the expression of anoA and decreased bacterial Sb(III) oxidation efficiency and Sb(III) resistant. In contrast, deletion of phoB1 did not obviously affect anoA's expression level and Sb(III) oxidation/resistance; (4) A putative Pho motif was predicted in several A. tumefaciens strains and electrophoretic mobility shift assay (EMSA) showed that PhoB2 could bind with the promoter sequence of anoA; (5) Site-directed mutagenesis and short fragment EMSA revealed the exact DNA binding sequence for the protein-DNA interaction. These results showed that PhoB2 positively regulates Sb(III) oxidation and PhoB2 is also associated with Sb(III) resistance. Such regulation mechanism may provide a great contribution for bacterial survival in the environment with Sb and for bioremediation application.
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Qiao Z, Huang J, Cao Y, Shi K, Wang G. Genetics and proteomics analyses reveal the roles of PhoB1 and PhoB2 regulators in bacterial responses to arsenite and phosphate. Res Microbiol 2019; 170:263-271. [PMID: 31279088 DOI: 10.1016/j.resmic.2019.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 06/18/2019] [Accepted: 06/21/2019] [Indexed: 11/25/2022]
Abstract
In bacteria, phosphate (Pi) stress response is governed by the two-component regulatory system, sensor kinase PhoR and its cognate response regulatory protein PhoB. The arsenite [As(III)]-oxidizing bacterium Agrobacterium tumefaciens GW4 contains two phoB genes, phoB1 and phoB2. phoB1 is adjacent to As(III)-oxidizing genes, however, the functions of PhoB1 and PhoB2 remain unclear. Here, phoB1 and phoB2 were each deleted in-frame, and proteomics, qRT-PCR and protein-DNA interaction were performed. We found that (1) phoB1 and phoB2 were both upregulated under low Pi conditions and phoB1 was induced by As(III), but phoB2 was not; (2) deletion of phoB1 reduced As(III)-oxidizing efficiency and protein-DNA interaction analysis showed PhoB1 could interact with aioXSR promoter to regulate As(III) oxidation; (3) deletions of phoB1 or phoB2 both reduced exopolysaccharides (EPS) synthesis; and (4) PhoB1 influenced Pi uptake, As(III) oxidation, EPS synthesis, TCA cycle, energy production and stress response with As(III), and PhoB2 was associated with Pi uptake and EPS synthesis in low Pi conditions. These results showed PhoB1 and PhoB2 were both involved in Pi acquisition, PhoB1 was more important with As(III) and PhoB2 played a major role without As(III). Strain GW4 uses these two regulators to survive under low Pi and arsenic-rich environments.
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Affiliation(s)
- Zixu Qiao
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
| | - Jing Huang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
| | - Yajing Cao
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
| | - Kaixiang Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
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Expression of Genes and Proteins Involved in Arsenic Respiration and Resistance in Dissimilatory Arsenate-Reducing Geobacter sp. Strain OR-1. Appl Environ Microbiol 2019; 85:AEM.00763-19. [PMID: 31101608 DOI: 10.1128/aem.00763-19] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 05/08/2019] [Indexed: 12/13/2022] Open
Abstract
The reduction of arsenate [As(V)] to arsenite [As(III)] by dissimilatory As(V)-reducing bacteria, such as Geobacter spp., may play a significant role in arsenic release from anaerobic sediments into groundwater. The biochemical and molecular mechanisms by which these bacteria cope with this toxic element remain unclear. In this study, the expression of several genes involved in arsenic respiration (arr) and resistance (ars) was determined using Geobacter sp. strain OR-1, the only cultured Geobacter strain capable of As(V) respiration. In addition, proteins expressed differentially under As(V)-respiring conditions were identified by semiquantitative proteomic analysis. Dissimilatory As(V) reductase (Arr) of strain OR-1 was localized predominantly in the periplasmic space, and the transcription of its gene (arrA) was upregulated under As(V)-respiring conditions. The transcription of the detoxifying As(V) reductase gene (arsC) was also upregulated, but its induction required 500 times higher concentration of As(III) (500 μM) than did the arrA gene. Comparative proteomic analysis revealed that in addition to the Arr and Ars proteins, proteins involved in the following processes were upregulated under As(V)-respiring conditions: (i) protein folding and assembly for rescue of proteins with oxidative damage, (ii) DNA replication and repair for restoration of DNA breaks, (iii) anaplerosis and gluconeogenesis for sustainable energy production and biomass formation, and (iv) protein and nucleotide synthesis for the replacement of damaged proteins and nucleotides. These results suggest that strain OR-1 copes with arsenic stress by orchestrating pleiotropic processes that enable this bacterium to resist and actively metabolize arsenic.IMPORTANCE Dissimilatory As(V)-reducing bacteria, such as Geobacter spp., play significant roles in arsenic release and contamination in groundwater and threaten the health of people worldwide. However, the biochemical and molecular mechanisms by which these bacteria cope with arsenic toxicity remain unclear. In this study, it was found that both respiratory and detoxifying As(V) reductases of a dissimilatory As(V)-reducing bacterium, Geobacter sp. strain OR-1, were upregulated under As(V)-respiring conditions. In addition, various proteins expressed specifically or more abundantly in strain OR-1 under arsenic stress were identified. Strain OR-1 actively metabolizes arsenic while orchestrating various metabolic processes that repair oxidative damage caused by arsenic. Such information is useful in assessing and identifying possible countermeasures for the prevention of microbial arsenic release in nature.
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Rawle RA, Kang YS, Bothner B, Wang G, McDermott TR. Transcriptomics analysis defines global cellular response of Agrobacterium tumefaciens 5A to arsenite exposure regulated through the histidine kinases PhoR and AioS. Environ Microbiol 2019; 21:2659-2676. [PMID: 30815967 DOI: 10.1111/1462-2920.14577] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 01/28/2019] [Accepted: 02/26/2019] [Indexed: 11/29/2022]
Abstract
In environments where arsenic and microbes coexist, microbes are the principal drivers of arsenic speciation, which directly affects bioavailability, toxicity and bioaccumulation. Speciation reactions influence arsenic behaviour in environmental systems, directly affecting human and agricultural exposures. Arsenite oxidation decreases arsenic toxicity and mobility in the environment, and therefore understanding its regulation and overall influence on cellular metabolism is of significant interest. The arsenite oxidase (AioBA) is regulated by a three-component signal transduction system AioXSR, which is in turn regulated by the phosphate stress response, with PhoR acting as the master regulator. Using RNA-sequencing, we characterized the global effects of arsenite on gene expression in Agrobacterium tumefaciens 5A. To further elucidate regulatory controls, mutant strains for histidine kinases PhoR and AioS were employed, and illustrate that in addition to arsenic metabolism, a host of other functional responses are regulated in parallel. Impacted functions include arsenic and phosphate metabolism, carbohydrate metabolism, solute transport systems and iron metabolism, in addition to others. These findings contribute significantly to the current understanding of the metabolic impact and genetic circuitry involved during arsenite exposure in bacteria. This informs how arsenic contamination will impact microbial activities involving several biogeochemical cycles in nature.
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Affiliation(s)
- Rachel A Rawle
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Yoon-Suk Kang
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717, USA
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Timothy R McDermott
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717, USA
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16
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Efflux Transporter ArsK Is Responsible for Bacterial Resistance to Arsenite, Antimonite, Trivalent Roxarsone, and Methylarsenite. Appl Environ Microbiol 2018; 84:AEM.01842-18. [PMID: 30315082 DOI: 10.1128/aem.01842-18] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/09/2018] [Indexed: 11/20/2022] Open
Abstract
Arsenic-resistant bacteria have evolved various efflux systems for arsenic resistance. Five arsenic efflux proteins, ArsB, Acr3, ArsP, ArsJ, and MSF1, have been reported. In this study, comprehensive analyses were performed to study the function of a putative major facilitator superfamily gene, arsK, and the regulation of arsK transcriptional expression in Agrobacterium tumefaciens GW4. We found that (i) arsK is located on an arsenic gene island in strain GW4. ArsK orthologs are widely distributed in arsenic-resistant bacteria and are phylogenetically divergent from the five reported arsenic efflux proteins, indicating that it may be a novel arsenic efflux transporter. (ii) Reporter gene assays showed that the expression of arsK was induced by arsenite [As(III)], antimonite [Sb(III)], trivalent roxarsone [Rox(III)], methylarsenite [MAs(III)], and arsenate [As(V)]. (iii) Heterologous expression of ArsK in an arsenic-hypersensitive Escherichia coli strain showed that ArsK was essential for resistance to As(III), Sb(III), Rox(III), and MAs(III) but not to As(V), dimethylarsenite [dimethyl-As(III)], or Cd(II). (iv) ArsK reduced the cellular accumulation of As(III), Sb(III), Rox(III), and MAs(III) but not to As(V) or dimethyl-As(III). (v) A putative arsenic regulator gene arsR2 was cotranscribed with arsK, and (vi) ArsR2 interacted with the arsR2-arsK promoter region without metalloids and was derepressed by As(III), Sb(III), Rox(III), and MAs(III), indicating the repression activity of ArsR2 for the transcription of arsK These results demonstrate that ArsK is a novel arsenic efflux protein for As(III), Sb(III), Rox(III), and MAs(III) and is regulated by ArsR2. Bacteria use the arsR2-arsK operon for resistance to several trivalent arsenicals or antimonials.IMPORTANCE The metalloid extrusion systems are very important bacterial resistance mechanisms. Each of the previously reported ArsB, Acr3, ArsP, ArsJ, and MSF1 transport proteins conferred only inorganic or organic arsenic/antimony resistance. In contrast, ArsK confers resistance to several inorganic and organic trivalent arsenicals and antimonials. The identification of the novel efflux transporter ArsK enriches our understanding of bacterial resistance to trivalent arsenite [As(III)], antimonite [Sb(III)], trivalent roxarsone [Rox(III)], and methylarsenite [MAs(III)].
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17
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Wang Q, Kang YS, Alowaifeer A, Shi K, Fan X, Wang L, Jetter J, Bothner B, Wang G, McDermott TR. Phosphate starvation response controls genes required to synthesize the phosphate analog arsenate. Environ Microbiol 2018; 20:1782-1793. [PMID: 29575522 DOI: 10.1111/1462-2920.14108] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 02/16/2018] [Accepted: 03/14/2018] [Indexed: 11/29/2022]
Abstract
Environmental arsenic poisoning affects roughly 200 million people worldwide. The toxicity and mobility of arsenic in the environment is significantly influenced by microbial redox reactions, with arsenite (AsIII ) being more toxic than arsenate (AsV ). Microbial oxidation of AsIII to AsV is known to be regulated by the AioXSR signal transduction system and viewed to function for detoxification or energy generation. Here, we show that AsIII oxidation is ultimately regulated by the phosphate starvation response (PSR), requiring the sensor kinase PhoR for expression of the AsIII oxidase structural genes aioBA. The PhoRB and AioSR signal transduction systems are capable of transphosphorylation cross-talk, closely integrating AsIII oxidation with the PSR. Further, under PSR conditions, AsV significantly extends bacterial growth and accumulates in the lipid fraction to the apparent exclusion of phosphorus. This could spare phosphorus for nucleic acid synthesis or triphosphate metabolism wherein unstable arsenic esters are not tolerated, thereby enhancing cell survival potential. We conclude that AsIII oxidation is logically part of the bacterial PSR, enabling the synthesis of the phosphate analog AsV to replace phosphorus in specific biomolecules or to synthesize other molecules capable of a similar function, although not for total replacement of cellular phosphate.
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Affiliation(s)
- Qian Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.,Departments of Land Resources & Environmental Sciences, Montana State University, Bozeman, MT 59717, USA
| | - Yoon-Suk Kang
- Departments of Land Resources & Environmental Sciences, Montana State University, Bozeman, MT 59717, USA
| | - Abdullah Alowaifeer
- Departments of Land Resources & Environmental Sciences, Montana State University, Bozeman, MT 59717, USA
| | - Kaixiang Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Xia Fan
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Lu Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Jonathan Jetter
- Departments of Land Resources & Environmental Sciences, Montana State University, Bozeman, MT 59717, USA
| | - Brian Bothner
- Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Timothy R McDermott
- Departments of Land Resources & Environmental Sciences, Montana State University, Bozeman, MT 59717, USA
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18
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Shi K, Wang Q, Fan X, Wang G. Proteomics and genetic analyses reveal the effects of arsenite oxidation on metabolic pathways and the roles of AioR in Agrobacterium tumefaciens GW4. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 235:700-709. [PMID: 29339339 DOI: 10.1016/j.envpol.2018.01.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 01/02/2018] [Accepted: 01/02/2018] [Indexed: 06/07/2023]
Abstract
A heterotrophic arsenite [As(III)]-oxidizing bacterium Agrobacterium tumefaciens GW4 isolated from As(III)-rich groundwater sediment showed high As(III) resistance and could oxidize As(III) to As(V). The As(III) oxidation could generate energy and enhance growth, and AioR was the regulator for As(III) oxidase. To determine the related metabolic pathways mediated by As(III) oxidation and whether AioR regulated other cellular responses to As(III), isobaric tags for relative and absolute quantitation (iTRAQ) was performed in four treatments, GW4 (+AsIII)/GW4 (-AsIII), GW4-ΔaioR (+AsIII)/GW4-ΔaioR (-AsIII), GW4-ΔaioR (-AsIII)/GW4 (-AsIII) and GW4-ΔaioR (+AsIII)/GW4 (+AsIII). A total of 41, 71, 82 and 168 differentially expressed proteins were identified, respectively. Using electrophoretic mobility shift assay (EMSA) and qRT-PCR, 12 genes/operons were found to interact with AioR. These results indicate that As(III) oxidation alters several cellular processes related to arsenite, such as As resistance (ars operon), phosphate (Pi) metabolism (pst/pho system), TCA cycle, cell wall/membrane, amino acid metabolism and motility/chemotaxis. In the wild type with As(III), TCA cycle flow is perturbed, and As(III) oxidation and fermentation are the main energy resources. However, when strain GW4-ΔaioR lost the ability of As(III) oxidation, the TCA cycle is the main way to generate energy. A regulatory cellular network controlled by AioR is constructed and shows that AioR is the main regulator for As(III) oxidation, besides, several other functions related to As(III) are regulated by AioR in parallel.
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Affiliation(s)
- Kaixiang Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Qian Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Xia Fan
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
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19
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Huang K, Xu Y, Packianathan C, Gao F, Chen C, Zhang J, Shen Q, Rosen BP, Zhao FJ. Arsenic methylation by a novel ArsM As(III) S-adenosylmethionine methyltransferase that requires only two conserved cysteine residues. Mol Microbiol 2017; 107:265-276. [PMID: 29134708 DOI: 10.1111/mmi.13882] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 11/08/2017] [Accepted: 11/11/2017] [Indexed: 12/19/2022]
Abstract
Arsenic (As) biomethylation is an important component of the As biogeochemical cycle that can influence As toxicity and mobility in the environment. Biomethylation of As is catalyzed by the enzyme arsenite (As[III]) S-adenosylmethionine methyltransferase (ArsM). To date, all identified ArsM orthologs with As(III) methylation activities have four conserved cysteine residues, which are thought to be essential for As(III) methylation. Here, we isolated an As(III)-methylating bacterium, Bacillus sp. CX-1, and identified a gene encoding a S-adenosylmethionine methyltranserase termed BlArsM with low sequence similarities (≤ 39%) to other ArsMs. BlArsM has six cysteine residues (Cys10, Cys11, Cys145, Cys193, Cys195 and Cys268), three of which (Cys10, Cys145 and Cys195) align with conserved cysteine residues found in most ArsMs. BlarsM is constitutively expressed in Bacillus sp. CX-1. Heterologous expression of BlarsM conferred As(III) resistance. Purified BlArsM methylated both As(III) and methylarsenite (MAs[III]), with a final product of dimethylarsenate (DMAs[V]). When all six cysteines were individually altered to serine residues, only C145S and C195S derivatives lost the ability to methylate As(III) and MAs(III). The derivative C10S/C11S/C193S/C268S was still active. These results suggest that BlArsM is a novel As(III) S-adenosylmethionine methyltransferase requiring only two conserved cysteine residues. A model of As(III) methylation by BlArsM is proposed.
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Affiliation(s)
- Ke Huang
- Jiangsu Provincial Key Laboratory for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yan Xu
- Jiangsu Provincial Key Laboratory for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Charles Packianathan
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Fan Gao
- Jiangsu Provincial Key Laboratory for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Chuan Chen
- Jiangsu Provincial Key Laboratory for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jun Zhang
- Jiangsu Provincial Key Laboratory for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Qirong Shen
- Jiangsu Provincial Key Laboratory for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Barry P Rosen
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Fang-Jie Zhao
- Jiangsu Provincial Key Laboratory for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
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20
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Promotion and Rescue of Intracellular Brucella neotomae Replication during Coinfection with Legionella pneumophila. Infect Immun 2017; 85:IAI.00991-16. [PMID: 28264909 DOI: 10.1128/iai.00991-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 02/28/2017] [Indexed: 12/17/2022] Open
Abstract
We established a new Brucella neotomaein vitro model system for study of type IV secretion system-dependent (T4SS) pathogenesis in the Brucella genus. Importantly, B. neotomae is a rodent pathogen, and unlike B. abortus, B. melitensis, and B. suis, B. neotomae has not been observed to infect humans. It therefore can be handled more facilely using biosafety level 2 practices. More particularly, using a series of novel fluorescent protein and lux operon reporter systems to differentially label pathogens and track intracellular replication, we confirmed T4SS-dependent intracellular growth of B. neotomae in macrophage cell lines. Furthermore, B. neotomae exhibited early endosomal (LAMP-1) and late endoplasmic reticulum (calreticulin)-associated phagosome maturation. These findings recapitulate prior observations for human-pathogenic Brucella spp. In addition, during coinfection experiments with Legionella pneumophila, we found that defective intracellular replication of a B. neotomae T4SS virB4 mutant was rescued and baseline levels of intracellular replication of wild-type B. neotomae were significantly stimulated by coinfection with wild-type but not T4SS mutant L. pneumophila Using confocal microscopy, it was determined that intracellular colocalization of B. neotomae and L. pneumophila was required for rescue and that colocalization came at a cost to L. pneumophila fitness. These findings were not completely expected based on known temporal and qualitative differences in the intracellular life cycles of these two pathogens. Taken together, we have developed a new system for studying in vitroBrucella pathogenesis and found a remarkable T4SS-dependent interplay between Brucella and Legionella during macrophage coinfection.
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21
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Shi K, Fan X, Qiao Z, Han Y, McDermott TR, Wang Q, Wang G. Arsenite oxidation regulator AioR regulates bacterial chemotaxis towards arsenite in Agrobacterium tumefaciens GW4. Sci Rep 2017; 7:43252. [PMID: 28256605 PMCID: PMC5335332 DOI: 10.1038/srep43252] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 01/23/2017] [Indexed: 11/13/2022] Open
Abstract
Some arsenite [As(III)]-oxidizing bacteria exhibit positive chemotaxis towards As(III), however, the related As(III) chemoreceptor and regulatory mechanism remain unknown. The As(III)-oxidizing bacterium Agrobacterium tumefaciens GW4 displays positive chemotaxis towards 0.5–2 mM As(III). Genomic analyses revealed a putative chemoreceptor-encoding gene, mcp, located in the arsenic gene island and having a predicted promoter binding site for the As(III) oxidation regulator AioR. Expression of mcp and other chemotaxis related genes (cheA, cheY2 and fliG) was inducible by As(III), but not in the aioR mutant. Using capillary assays and intrinsic tryptophan fluorescence spectra analysis, Mcp was confirmed to be responsible for chemotaxis towards As(III) and to bind As(III) (but not As(V) nor phosphate) as part of the sensing mechanism. A bacterial one-hybrid system technique and electrophoretic mobility shift assays showed that AioR interacts with the mcp regulatory region in vivo and in vitro, and the precise AioR binding site was confirmed using DNase I foot-printing. Taken together, these results indicate that this Mcp is responsible for the chemotactic response towards As(III) and is regulated by AioR. Additionally, disrupting the mcp gene affected bacterial As(III) oxidation and growth, inferring that Mcp may exert some sort of functional connection between As(III) oxidation and As(III) chemotaxis.
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Affiliation(s)
- Kaixiang Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Xia Fan
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Zixu Qiao
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yushan Han
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Timothy R McDermott
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717, USA
| | - Qian Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.,Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717, USA
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
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22
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Oremland RS, Stolz JF. Metabolomic changes in response to toxic arsenite. Environ Microbiol 2017; 19:413-414. [DOI: 10.1111/1462-2920.13596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
| | - John F. Stolz
- Department of Biological Sciences; Duquesne University; Pittsburgh PA 15282 USA
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23
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An Oxidoreductase AioE is Responsible for Bacterial Arsenite Oxidation and Resistance. Sci Rep 2017; 7:41536. [PMID: 28128323 PMCID: PMC5270249 DOI: 10.1038/srep41536] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 12/19/2016] [Indexed: 11/08/2022] Open
Abstract
Previously, we found that arsenite (AsIII) oxidation could improve the generation of ATP/NADH to support the growth of Agrobacterium tumefaciens GW4. In this study, we found that aioE is induced by AsIII and located in the arsenic island near the AsIII oxidase genes aioBA and co-transcripted with the arsenic resistant genes arsR1-arsC1-arsC2-acr3-1. AioE belongs to TrkA family corresponding the electron transport function with the generation of NADH and H+. An aioE in-frame deletion strain showed a null AsIII oxidation and a reduced AsIII resistance, while a cytC mutant only reduced AsIII oxidation efficiency. With AsIII, aioE was directly related to the increase of NADH, while cytC was essential for ATP generation. In addition, cyclic voltammetry analysis showed that the redox potential (ORP) of AioBA and AioE were +0.297 mV vs. NHE and +0.255 mV vs. NHE, respectively. The ORP gradient is AioBA > AioE > CytC (+0.217 ~ +0.251 mV vs. NHE), which infers that electron may transfer from AioBA to CytC via AioE. The results indicate that AioE may act as a novel AsIII oxidation electron transporter associated with NADH generation. Since AsIII oxidation contributes AsIII detoxification, the essential of AioE for AsIII resistance is also reasonable.
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Tokmina-Lukaszewska M, Shi Z, Tripet B, McDermott TR, Copié V, Bothner B, Wang G. Metabolic response of Agrobacterium tumefaciens 5A to arsenite. Environ Microbiol 2017; 19:710-721. [PMID: 27871140 DOI: 10.1111/1462-2920.13615] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/24/2016] [Accepted: 11/16/2016] [Indexed: 11/26/2022]
Abstract
Wide-spread abundance in soil and water, coupled with high toxicity have put arsenic at the top of the list of environmental contaminants. Early studies demonstrated that both concentration and the valence state of inorganic arsenic (arsenite, As(III) vs. arsenate As(V)) can be modulated by microbes. Using genetics, transcriptomic and proteomic techniques, microbe-arsenic detoxification, respiratory As(V) reduction and As(III) oxidation have since been examined. The effect of arsenic exposure on whole-cell intracellular microbial metabolism, however, has not been extensively studied. We combined LC-MS and 1 H NMR to quantify metabolic changes in Agrobacterium tumefaciens (strain 5A) upon exposure to sub-lethal concentrations of As(III). Metabolomics analysis reveals global differences in metabolite concentrations between control and As(III) exposure groups, with significant perturbations to intermediates shuttling into and cycling within the TCA cycle. These data are most consistent with the disruption of two key TCA cycle enzymes, pyruvate dehydrogenase and α-ketoglutarate dehydrogenase. Glycolysis also appeared altered following As(III) stress, with carbon accumulating as complex saccharides. These observations suggest that an important consequence of As(III) contamination in nature will be to alter microbial carbon metabolism at the microbial community level and thus has the potential to foundationally impact all biogeochemical cycles in the environment.
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Affiliation(s)
| | - Zunji Shi
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA.,State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Brian Tripet
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA
| | - Timothy R McDermott
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, 59717, USA
| | - Valérie Copié
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
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Regulatory Activities of Four ArsR Proteins in Agrobacterium tumefaciens 5A. Appl Environ Microbiol 2016; 82:3471-3480. [PMID: 27037117 DOI: 10.1128/aem.00262-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 03/28/2016] [Indexed: 02/08/2023] Open
Abstract
UNLABELLED ArsR is a well-studied transcriptional repressor that regulates microbe-arsenic interactions. Most microorganisms have an arsR gene, but in cases where multiple copies exist, the respective roles or potential functional overlap have not been explored. We examined the repressors encoded by arsR1 and arsR2 (ars1 operon) and by arsR3 and arsR4 (ars2 operon) in Agrobacterium tumefaciens 5A. ArsR1 and ArsR4 are very similar in their primary sequences and diverge phylogenetically from ArsR2 and ArsR3, which are also quite similar to one another. Reporter constructs (lacZ) for arsR1, arsR2, and arsR4 were all inducible by As(III), but expression of arsR3 (monitored by reverse transcriptase PCR) was not influenced by As(III) and appeared to be linked transcriptionally to an upstream lysR-type gene. Experiments using a combination of deletion mutations and additional reporter assays illustrated that the encoded repressors (i) are not all autoregulatory as is typically known for ArsR proteins, (ii) exhibit variable control of each other's encoding genes, and (iii) exert variable control of other genes previously shown to be under the control of ArsR1. Furthermore, ArsR2, ArsR3, and ArsR4 appear to have an activator-like function for some genes otherwise repressed by ArsR1, which deviates from the well-studied repressor role of ArsR proteins. The differential regulatory activities suggest a complex regulatory network not previously observed in ArsR studies. The results indicate that fine-scale ArsR sequence deviations of the reiterated regulatory proteins apparently translate to different regulatory roles. IMPORTANCE Given the significance of the ArsR repressor in regulating various aspects of microbe-arsenic interactions, it is important to assess potential regulatory overlap and/or interference when a microorganism carries multiple copies of arsR This study explores this issue and shows that the four arsR genes in A. tumefaciens 5A, associated with two separate ars operons, encode proteins exhibiting various degrees of functional overlap with respect to autoregulation and cross-regulation, as well as control of other functional genes. In some cases, differences in regulatory activity are associated with only limited differences in protein primary structure. The experiments summarized herein also present evidence that ArsR proteins appear to have activator functions, representing novel regulatory activities for ArsR, previously known only to be a repressor.
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Andres J, Bertin PN. The microbial genomics of arsenic. FEMS Microbiol Rev 2016; 40:299-322. [DOI: 10.1093/femsre/fuv050] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2015] [Indexed: 12/17/2022] Open
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Liu H, Zhuang W, Zhang S, Rensing C, Huang J, Li J, Wang G. Global Regulator IscR Positively Contributes to Antimonite Resistance and Oxidation in Comamonas testosteroni S44. Front Mol Biosci 2015; 2:70. [PMID: 26734615 PMCID: PMC4683182 DOI: 10.3389/fmolb.2015.00070] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Accepted: 11/29/2015] [Indexed: 11/13/2022] Open
Abstract
Antimonial compounds can be found as a toxic contaminant in the environment. Knowledge on mechanisms of microbial Sb oxidation and its role in microbial tolerance are limited. Previously, we found that Comamonas testosteroni S44 was resistant to multiple heavy metals and was able to oxidize the toxic antimonite [Sb(III)] to the much less toxic antimonate [Sb(V)]. In this study, transposon mutagenesis was performed in C. testosteroni S44 to isolate genes responsible for Sb(III) resistance and oxidation. An insertion mutation into iscR, which regulates genes involved in the biosynthesis of Fe-S clusters, generated a strain called iscR-280. This mutant strain was complemented with a plasmid carrying iscR to generate strain iscR-280C. Compared to the wild type S44 and iscR-280C, strain iscR-280 showed lower resistance to Sb(III) and a lower Sb(III) oxidation rate. Strain iscR-280 also showed lower resistance to As(III), Cd(II), Cu(II), and H2O2. In addition, intracellular γ-glutamylcysteine ligase (γ-GCL) activity and glutathione (GSH) content were decreased in the mutated strain iscR-280. Real-time RT-PCR and lacZ fusion expression assay indicated that transcription of iscR and iscS was induced by Sb(III). Results of electrophoretic mobility shift assay (EMSA) and bacterial one-hybrid (B1H) system demonstrated a positive interaction between IscR and its promoter region. The diverse defective phenotypes and various expression patterns suggest a role for IscR in contributing to multi-metal(loid)s resistance and Sb(III) oxidation via Fe-S cluster biogenesis and oxidative stress protection. Bacterial Sb(III) oxidation is a detoxification reaction.
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Affiliation(s)
- Hongliang Liu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural UniversityWuhan, China; Shandong Provincial Research Center for Bioinformatic Engineering and Technique, School of Life Sciences, Shandong University of TechnologyZibo, China
| | - Weiping Zhuang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Shengzhe Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Christopher Rensing
- Department of Plant and Environmental Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Jun Huang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Jie Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
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Chen F, Cao Y, Wei S, Li Y, Li X, Wang Q, Wang G. Regulation of arsenite oxidation by the phosphate two-component system PhoBR in Halomonas sp. HAL1. Front Microbiol 2015; 6:923. [PMID: 26441863 PMCID: PMC4563254 DOI: 10.3389/fmicb.2015.00923] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 08/21/2015] [Indexed: 01/25/2023] Open
Abstract
Previously, the expression of arsenite [As(III)] oxidase genes aioBA was reported to be regulated by a three-component regulatory system, AioXSR, in a number of As(III)-oxidizing bacterial strains. However, the regulation mechanism is still unknown when aioXSR genes are absent in some As(III)-oxidizing bacterial genomes, such as in Halomonas sp. HAL1. In this study, transposon mutagenesis and gene knock-out mutation were performed, and two mutants, HAL1-phoR931 and HAL1-▵phoB, were obtained in strain HAL1. The phoR and phoB constitute a two-component system which is responsible for phosphate (Pi) acquisition and assimilation. Both of the mutants showed negative As(III)-oxidation phenotypes in low Pi condition (0.1 mM) but not under normal Pi condition (1 mM). The phoBR complementation strain HAL1-▵phoB-C reversed the mutants' null phenotypes back to wild type status. Meanwhile, lacZ reporter fusions using pCM-lacZ showed that the expression of phoBR and aioBA were both induced by As(III) but were not induced in HAL1-phoR931 and HAL1-▵phoB. Using 15 consensus Pho box sequences, a putative Pho box was found in the aioBA regulation region. PhoB was able to bind to the putative Pho box in vivo (bacterial one-hybrid detection) and in vitro (electrophoretic mobility gel shift assay), and an 18-bp binding sequence containing nine conserved bases were determined. This study provided the evidence that PhoBR regulates the expression of aioBA in Halomonas sp. HAL1 under low Pi condition. The new regulation model further implies the close metabolic connection between As and Pi.
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Affiliation(s)
- Fang Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Yajing Cao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Sha Wei
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Yanzhi Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Xiangyang Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Qian Wang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
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Li J, Wang Q, Li M, Yang B, Shi M, Guo W, McDermott TR, Rensing C, Wang G. Proteomics and Genetics for Identification of a Bacterial Antimonite Oxidase in Agrobacterium tumefaciens. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:5980-5989. [PMID: 25909855 DOI: 10.1021/es506318b] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Antimony (Sb) and its compounds are listed by the United States Environmental Protection Agency (USEPA, 1979) and the European Union (CEC, 1976) as a priority pollutant. Microbial redox transformations are presumed to be an important part of antimony cycling in nature; however, regulation of these processes and the enzymology involved are unknown. In this study, comparative proteomics and reverse transcriptase-PCR analysis of Sb(III)-oxidizing bacterium Agrobacterium tumefaciens GW4 revealed an oxidoreductase (anoA) is widely distributed in microorganisms, including at least some documented to be able to oxidize Sb(III). Deletion of the anoA gene reduced Sb(III) resistance and decreased Sb(III) oxidation by ∼27%, whereas the anoA complemented strain was similar to the wild type GW4 and a GW4 anoA overexpressing strain increased Sb(III) oxidation by ∼34%. Addition of Sb(III) up-regulated anoA expression and cloning anoA to Escherichia coli demonstrated direct transferability of this activity. A His-tag purified AnoA was found to require NADP(+) as cofactor, and exhibited a K(m) for Sb(III) of 64 ± 10 μM and a V(max) of 150 ± 7 nmol min(-1) mg(-1). This study contributes important initial steps toward a mechanistic understanding of microbe-antimony interactions and enhances our understanding of how microorganisms participate in antimony biogeochemical cycling in nature.
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Affiliation(s)
- Jingxin Li
- †State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China
| | - Qian Wang
- †State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China
| | - Mingshun Li
- †State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China
| | - Birong Yang
- †State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China
| | - Manman Shi
- †State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China
| | - Wei Guo
- †State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China
| | - Timothy R McDermott
- ‡Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, Montana 59717, United States
| | - Christopher Rensing
- §Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, DK-1871, Denmark
| | - Gejiao Wang
- †State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China
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Santos-Beneit F. The Pho regulon: a huge regulatory network in bacteria. Front Microbiol 2015; 6:402. [PMID: 25983732 PMCID: PMC4415409 DOI: 10.3389/fmicb.2015.00402] [Citation(s) in RCA: 214] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 04/17/2015] [Indexed: 12/15/2022] Open
Abstract
One of the most important achievements of bacteria is its capability to adapt to the changing conditions of the environment. The competition for nutrients with other microorganisms, especially in the soil, where nutritional conditions are more variable, has led bacteria to evolve a plethora of mechanisms to rapidly fine-tune the requirements of the cell. One of the essential nutrients that are normally found in low concentrations in nature is inorganic phosphate (Pi). Bacteria, as well as other organisms, have developed several systems to cope for the scarcity of this nutrient. To date, the unique mechanism responding to Pi starvation known in detail is the Pho regulon, which is normally controlled by a two component system and constitutes one of the most sensible and efficient regulatory mechanisms in bacteria. Many new members of the Pho regulon have emerged in the last years in several bacteria; however, there are still many unknown questions regarding the activation and function of the whole system. This review describes the most important findings of the last three decades in relation to Pi regulation in bacteria, including: the PHO box, the Pi signaling pathway and the Pi starvation response. The role of the Pho regulon in nutritional regulation cross-talk, secondary metabolite production, and pathogenesis is discussed in detail.
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Affiliation(s)
- Fernando Santos-Beneit
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne UK
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Abstract
Arsenic and antimony are toxic metalloids and are considered priority environmental pollutants by the U.S. Environmental Protection Agency. Significant advances have been made in understanding microbe-arsenic interactions and how they influence arsenic redox speciation in the environment. However, even the most basic features of how and why a microorganism detects and reacts to antimony remain poorly understood. Previous work with Agrobacterium tumefaciens strain 5A concluded that oxidation of antimonite [Sb(III)] and arsenite [As(III)] required different biochemical pathways. Here, we show with in vivo experiments that a mutation in aioA [encoding the large subunit of As(III) oxidase] reduces the ability to oxidize Sb(III) by approximately one-third relative to the ability of the wild type. Further, in vitro studies with the purified As(III) oxidase from Rhizobium sp. strain NT-26 (AioA shares 94% amino acid sequence identity with AioA of A. tumefaciens) provide direct evidence of Sb(III) oxidation but also show a significantly decreased Vmax compared to that of As(III) oxidation. The aioBA genes encoding As(III) oxidase are induced by As(III) but not by Sb(III), whereas arsR gene expression is induced by both As(III) and Sb(III), suggesting that detection and transcriptional responses for As(III) and Sb(III) differ. While Sb(III) and As(III) are similar with respect to cellular extrusion (ArsB or Acr3) and interaction with ArsR, they differ in the regulatory mechanisms that control the expression of genes encoding the different Ars or Aio activities. In summary, this study documents an enzymatic basis for microbial Sb(III) oxidation, although additional Sb(III) oxidation activity also is apparent in this bacterium.
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Wang Q, Qin D, Zhang S, Wang L, Li J, Rensing C, McDermott TR, Wang G. Fate of arsenate following arsenite oxidation in Agrobacterium tumefaciens GW4. Environ Microbiol 2014; 17:1926-40. [PMID: 24673976 DOI: 10.1111/1462-2920.12465] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 03/20/2014] [Indexed: 10/25/2022]
Abstract
The fate of arsenate (As(V) ) generated by microbial arsenite (As(III) ) oxidation is poorly understood. Agrobacterium tumefaciens wild-type strain (GW4) was studied to determine how the cell copes with As(V) generated in batch culture. GW4 grown heterotrophically with mannitol used As(III) as a supplemental energy supply as reflected by enhanced growth and increased cellular levels of NADH and ATP. Under low phosphate (Pi) conditions and presence of As(III) oxidation, up to ∼ 50% of the resulting As(V) was taken up and found associated with the periplasm, membrane or cytoplasm fractions of the cells. Arsenic was found associated with proteins and polar lipids, but not in nucleic acids or sugars. Thin-layer chromatography and gas chromatography-mass spectrometry analysis suggested the presence of arsenolipids in membranes, presumably as part of the bilayer structure of the cell membrane and replacing Pi under Pi-limiting conditions. The potential role of a Pi-binding protein (PstS) for As(V) uptake was assessed with the His-tag purified protein. Intrinsic tryptophan fluorescence spectra analysis suggests that PstS can bind As(V) , but with lower affinity as compared with Pi. In early stationary phase cells, the As(V) : Pi ratio was approximately 4.3 and accompanied by an altered cell ultrastructure.
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Affiliation(s)
- Qian Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Dong Qin
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Shengzhe Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Lu Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jingxin Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Christopher Rensing
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Timothy R McDermott
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, 59717, USA
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
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Kang YS, Shi Z, Bothner B, Wang G, McDermott TR. Involvement of the Acr3 and DctA anti-porters in arsenite oxidation in Agrobacterium tumefaciens 5A. Environ Microbiol 2014; 17:1950-62. [PMID: 24674103 DOI: 10.1111/1462-2920.12468] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 03/22/2014] [Indexed: 12/01/2022]
Abstract
Microbial arsenite (AsIII) oxidation forms a critical piece of the arsenic cycle in nature, though our understanding of how and why microorganisms oxidize AsIII remains rudimentary. Our model organism Agrobacterium tumefaciens 5A contains two distinct ars operons (ars1 and ars2) that are similar in their coding region content. The ars1 operon is located nearby the aio operon that is essential for AsIII oxidation. The AsIII/H(+) anti-porters encoded by acr3-1 and acr3-2 are required for maximal AsIII and antimonite (SbIII) resistance, but acr3-1 (negatively regulated by ArsR-1) appears more active in this regard and also required for AsIII oxidation and expression of aioBA. A malate-phosphate anti-porter DctA is regulated by RpoN and AsIII, and is required for normal growth with malate as a sole carbon source. Qualitatively, a ΔdctA mutant was normal for AsIII oxidation and AsIII/SbIII resistance at metalloid concentrations inhibitory to the Δacr3-1 mutant; however, aioBA induction kinetics was significantly phase-shift delayed. Acr3 involvement in AsIII/SbIII resistance is reasonably well understood, but the role of Acr3 and DctA anti-porters in AsIII oxidation and its regulation is unexpected, and suggests that controlled AsIII trafficking across the cytoplasmic membrane is important to a process understood to occur in the periplasm.
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Affiliation(s)
- Yoon-Suk Kang
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, 59717, USA
| | - Zunji Shi
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, 59717, USA.,State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Timothy R McDermott
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, 59717, USA
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Li X, Zhang L, Wang G. Genomic evidence reveals the extreme diversity and wide distribution of the arsenic-related genes in Burkholderiales. PLoS One 2014; 9:e92236. [PMID: 24632831 PMCID: PMC3954881 DOI: 10.1371/journal.pone.0092236] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 02/19/2014] [Indexed: 11/18/2022] Open
Abstract
So far, numerous genes have been found to associate with various strategies to resist and transform the toxic metalloid arsenic (here, we denote these genes as "arsenic-related genes"). However, our knowledge of the distribution, redundancies and organization of these genes in bacteria is still limited. In this study, we analyzed the 188 Burkholderiales genomes and found that 95% genomes harbored arsenic-related genes, with an average of 6.6 genes per genome. The results indicated: a) compared to a low frequency of distribution for aio (arsenite oxidase) (12 strains), arr (arsenate respiratory reductase) (1 strain) and arsM (arsenite methytransferase)-like genes (4 strains), the ars (arsenic resistance system)-like genes were identified in 174 strains including 1,051 genes; b) 2/3 ars-like genes were clustered as ars operon and displayed a high diversity of gene organizations (68 forms) which may suggest the rapid movement and evolution for ars-like genes in bacterial genomes; c) the arsenite efflux system was dominant with ACR3 form rather than ArsB in Burkholderiales; d) only a few numbers of arsM and arrAB are found indicating neither As III biomethylation nor AsV respiration is the primary mechanism in Burkholderiales members; (e) the aio-like gene is mostly flanked with ars-like genes and phosphate transport system, implying the close functional relatedness between arsenic and phosphorus metabolisms. On average, the number of arsenic-related genes per genome of strains isolated from arsenic-rich environments is more than four times higher than the strains from other environments. Compared with human, plant and animal pathogens, the environmental strains possess a larger average number of arsenic-related genes, which indicates that habitat is likely a key driver for bacterial arsenic resistance.
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Affiliation(s)
- Xiangyang Li
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, P. R. China
| | - Linshuang Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, P. R. China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, P. R. China
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Zhang S, Rensing C, Zhu YG. Cyanobacteria-mediated arsenic redox dynamics is regulated by phosphate in aquatic environments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:994-1000. [PMID: 24359134 DOI: 10.1021/es403836g] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Studies of cyanobacteria in environments where arsenic (As) and phosphate (P) both occur in significant concentrations have so far only focused on the effect of P on As(V) toxicity and bioaccumulation, with little attention to the influence of P on As redox transformations. Our study revealed that As(III) oxidation by Synechocystis appeared to be more effective with increased P levels. We demonstrated that the higher As(III) percentage in the medium under P-limited conditions was due to enhanced As(V) uptake and the subsequent efflux of intracellularly reduced As(III) which in turn contributed to higher As(III) concentrations in the medium. Arsenic redox changes by Synechocystis under P-limited conditions is a dynamic cyclic process that includes the following: surface As(III) oxidation (either in the periplasm or near the outer membrane), As(V) uptake, intracellular As(V) reduction, and As(III) efflux. These observations not only expand our understanding of how P influences microbial As redox metabolisms but also provide insights into the biogeochemical coupling between As and P in As contaminated eutrophic aquatic environments and artificial wetland-paddy fields.
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Affiliation(s)
- Siyu Zhang
- State Key Lab of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, People's Republic of China
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Tomczyk-Żak K, Kaczanowski S, Drewniak Ł, Dmoch Ł, Sklodowska A, Zielenkiewicz U. Bacteria diversity and arsenic mobilization in rock biofilm from an ancient gold and arsenic mine. THE SCIENCE OF THE TOTAL ENVIRONMENT 2013; 461-462:330-340. [PMID: 23743145 DOI: 10.1016/j.scitotenv.2013.04.087] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 04/23/2013] [Accepted: 04/28/2013] [Indexed: 06/02/2023]
Abstract
In this paper we characterize the biofilm community from an ancient Złoty Stok gold and arsenic mine. Bacterial diversity was examined using a culture-independent technique based on 16S rRNA gene amplification, cloning and sequencing. We show that unexpectedly the microbial diversity of this community was extremely high (more than 190 OTUs detected), with the most numerous members from Rhizobiales (α-Proteobacteria). Although the level of rock biofilm diversity was similar to the microbial mat community we have previously characterized in the same adit, its taxonomic composition was completely different. Detailed analysis of functional arrA and aioA genes, chemical properties of siderophores found in pore water as well as the biofilm chemical composition suggest that the biofilm community contributes to arsenic pollution of surrounding water in a biogeochemical cycle similar to the one observed in bacterial mats. To interpret our results concerning the biological arsenic cycle, we applied the theory of ecological pyramids of Charles Elton.
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Affiliation(s)
- Karolina Tomczyk-Żak
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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Slyemi D, Moinier D, Talla E, Bonnefoy V. Organization and regulation of the arsenite oxidase operon of the moderately acidophilic and facultative chemoautotrophic Thiomonas arsenitoxydans. Extremophiles 2013; 17:911-20. [DOI: 10.1007/s00792-013-0573-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 07/30/2013] [Indexed: 10/26/2022]
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Kruger MC, Bertin PN, Heipieper HJ, Arsène-Ploetze F. Bacterial metabolism of environmental arsenic--mechanisms and biotechnological applications. Appl Microbiol Biotechnol 2013; 97:3827-41. [PMID: 23546422 DOI: 10.1007/s00253-013-4838-5] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 03/05/2013] [Accepted: 03/06/2013] [Indexed: 01/13/2023]
Abstract
Arsenic causes threats for environmental and human health in numerous places around the world mainly due to its carcinogenic potential at low doses. Removing arsenic from contaminated sites is hampered by the occurrence of several oxidation states with different physicochemical properties. The actual state of arsenic strongly depends on its environment whereby microorganisms play important roles in its geochemical cycle. Due to its toxicity, nearly all organisms possess metabolic mechanisms to resist its hazardous effects, mainly by active extrusion, but also by extracellular precipitation, chelation, and intracellular sequestration. Some microbes are even able to actively use various arsenic compounds in their metabolism, either as an electron donor or as a terminal electron acceptor for anaerobic respiration. Some microorganisms can also methylate inorganic arsenic, probably as a resistance mechanism, or demethylate organic arsenicals. Bioavailability of arsenic in water and sediments is strongly influenced by such microbial activities. Therefore, understanding microbial reactions to arsenic is of importance for the development of technologies for improved bioremediation of arsenic-contaminated waters and environments. This review gives an overview of the current knowledge on bacterial interactions with arsenic and on biotechnologies for its detoxification and removal.
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Affiliation(s)
- Martin C Kruger
- Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Permoserstr. 15, 04318 Leipzig, Germany
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Huertas MJ, Michán C. Indispensable or toxic? The phosphate versus arsenate debate. Microb Biotechnol 2012; 6:209-11. [PMID: 23280010 PMCID: PMC3815915 DOI: 10.1111/1751-7915.12024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- M José Huertas
- Instituto de Bioquímica Vegetal y Fotosíntesis, Centro de Investigaciones Isla de la Cartuja, Universidad de Sevilla-CSIC, Av. Américo Vespucio 49, 41092 Seville, Spain
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