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Zhao B, Zhang Z, Feng K, Peng X, Wang D, Cai W, Liu W, Wang A, Deng Y. Inoculum source determines the stress resistance of electroactive functional taxa in biofilms: A metagenomic perspective. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 945:174018. [PMID: 38906302 DOI: 10.1016/j.scitotenv.2024.174018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 05/20/2024] [Accepted: 06/13/2024] [Indexed: 06/23/2024]
Abstract
The inoculum has a crucial impact on bioreactor initialization and performance. However, there is currently a lack of guidance on selecting appropriate inocula for applications in environmental biotechnology. In this study, we applied microbial electrolysis cells (MECs) as models to investigate the differences in the functional potential of electroactive microorganisms (EAMs) within anodic biofilms developed from four different inocula (natural or artificial), using shotgun metagenomic techniques. We specifically focused on extracellular electron transfer (EET) function and stress resistance, which affect the performance and stability of MECs. Community profiling revealed that the family Geobacteraceae was the key EAM taxon in all biofilms, with Geobacter as the dominant genus. The c-type cytochrome gene imcH showed universal importance for Geobacteraceae EET and was utilized as a marker gene to evaluate the EET potential of EAMs. Additionally, stress response functional genes were used to assess the stress resistance potential of Geobacter species. Comparative analysis of imcH gene abundance revealed that EAMs with comparable overall EET potential could be enriched from artificial and natural inocula (P > 0.05). However, quantification of stress response gene copy numbers in the genomes demonstrated that EAMs originating from natural inocula possessed superior stress resistance potential (196 vs. 163). Overall, this study provides novel perspectives on the inoculum effect in bioreactors and offers theoretical guidance for selecting inoculum in environmental engineering applications.
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Affiliation(s)
- Bo Zhao
- CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Zhaojing Zhang
- Institute of Marine Science and Technology, Shandong University, Qingdao 266237, China
| | - Kai Feng
- CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing 100085, China
| | - Xi Peng
- CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Danrui Wang
- CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Weiwei Cai
- School of Civil Engineering, Beijing Jiaotong University, Beijing, China
| | - Wenzong Liu
- State Key Lab of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China
| | - Aijie Wang
- CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing 100085, China; State Key Lab of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China
| | - Ye Deng
- CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China.
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Zhong H, Lyu H, Wang Z, Tian J, Wu Z. Application of dissimilatory iron-reducing bacteria for the remediation of soil and water polluted with chlorinated organic compounds: Progress, mechanisms, and directions. CHEMOSPHERE 2024; 352:141505. [PMID: 38387660 DOI: 10.1016/j.chemosphere.2024.141505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 02/16/2024] [Accepted: 02/19/2024] [Indexed: 02/24/2024]
Abstract
Chlorinated organic compounds are widely used as solvents, but they are pollutants that can have adverse effects on the environment and human health. Dissimilatory iron-reducing bacteria (DIRB) such as Shewanella and Geobacter have been applied to treat a wide range of halogenated organic compounds due to their specific biological properties. Until now, there has been no systematic review on the mechanisms of direct or indirect degradation of halogenated organic compounds by DIRB. This work summarizes the discussion of DIRB's ability to enhance the dechlorination of reaction systems through different pathways, both biological and biochemical. For biological dechlorination, some DIRB have self-dechlorination capabilities that directly dechlorinate by hydrolysis. Adjustment of dechlorination genes through genetic engineering can improve the dechlorination capabilities of DIRB. DIRB can also adjust the capacity for the microbial community to dechlorinate and provide nutrients to enhance the expression of dechlorination genes in other bacteria. In biochemical dechlorination, DIRB bioconverts Fe(III) to Fe(II), which is capable of dichlorination. On this basis, the DIRB-driven Fenton reaction can efficiently degrade chlorinated organics by continuously maintaining anoxic conditions to generate Fe(II) and oxic conditions to generate H2O2. DIRB can drive microbial fuel cells due to their electroactivity and have a good dechlorination capacity at low levels of energy consumption. The contribution of DIRB to the removal of pesticides, antibiotics and POPs is summarized. Then the DIRB electron transfer mechanism is discussed, which is core to their ability to dechlorinate. Finally, the prospect of future work on the removal of chlorine-containing organic pollutants by DIRB is presented, and the main challenges and further research directions are suggested.
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Affiliation(s)
- Hua Zhong
- Tianjin Key Laboratory of Clean Energy and Pollution Control, Hebei Engineering Research Center of Pollution Control in Power System, School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Honghong Lyu
- Tianjin Key Laboratory of Clean Energy and Pollution Control, Hebei Engineering Research Center of Pollution Control in Power System, School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China.
| | - Zhiqiang Wang
- Tianjin Key Laboratory of Clean Energy and Pollution Control, Hebei Engineering Research Center of Pollution Control in Power System, School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Jingya Tian
- Tianjin Key Laboratory of Clean Energy and Pollution Control, Hebei Engineering Research Center of Pollution Control in Power System, School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Zhineng Wu
- Tianjin Key Laboratory of Clean Energy and Pollution Control, Hebei Engineering Research Center of Pollution Control in Power System, School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China.
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Pimenta AI, Paquete CM, Morgado L, Edwards MJ, Clarke TA, Salgueiro CA, Pereira IAC, Duarte AG. Characterization of the inner membrane cytochrome ImcH from Geobacter reveals its importance for extracellular electron transfer and energy conservation. Protein Sci 2023; 32:e4796. [PMID: 37779214 PMCID: PMC10601379 DOI: 10.1002/pro.4796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 08/30/2023] [Accepted: 09/16/2023] [Indexed: 10/03/2023]
Abstract
Electroactive bacteria combine the oxidation of carbon substrates with an extracellular electron transfer (EET) process that discharges electrons to an electron acceptor outside the cell. This process involves electron transfer through consecutive redox proteins that efficiently connect the inner membrane to the cell exterior. In this study, we isolated and characterized the quinone-interacting membrane cytochrome c ImcH from Geobacter sulfurreducens, which is involved in the EET process to high redox potential acceptors. Spectroscopic and electrochemical studies show that ImcH hemes have low midpoint redox potentials, ranging from -150 to -358 mV, and connect the oxidation of the quinol-pool to EET, transferring electrons to the highly abundant periplasmic cytochrome PpcA with higher affinity than to its homologues. Despite the larger number of hemes and transmembrane helices, the ImcH structural model has similarities with the NapC/NirT/NrfH superfamily, namely the presence of a quinone-binding site on the P-side of the membrane. In addition, the first heme, likely involved on the quinol oxidation, has apparently an unusual His/Gln coordination. Our work suggests that ImcH is electroneutral and transfers electrons and protons to the same side of the membrane, contributing to the maintenance of a proton motive force and playing a central role in recycling the menaquinone pool.
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Affiliation(s)
- Andreia I. Pimenta
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaOeirasPortugal
| | - Catarina M. Paquete
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaOeirasPortugal
| | - Leonor Morgado
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, NOVA School of Science and TechnologyUniversidade NOVA de LisboaCaparicaPortugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and TechnologyUniversidade NOVA de LisboaCaparicaPortugal
| | | | - Thomas A. Clarke
- Centre for Molecular and Structural Biochemistry, School of Biological SciencesUniversity of East AngliaNorwichUK
| | - Carlos A. Salgueiro
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, NOVA School of Science and TechnologyUniversidade NOVA de LisboaCaparicaPortugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and TechnologyUniversidade NOVA de LisboaCaparicaPortugal
| | - Inês A. C. Pereira
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaOeirasPortugal
| | - Américo G. Duarte
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaOeirasPortugal
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Zhou J, Smith JA, Li M, Holmes DE. Methane production by Methanothrix thermoacetophila via direct interspecies electron transfer with Geobacter metallireducens. mBio 2023; 14:e0036023. [PMID: 37306514 PMCID: PMC10470525 DOI: 10.1128/mbio.00360-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 04/13/2023] [Indexed: 06/13/2023] Open
Abstract
Methanothrix is widely distributed in natural and artificial anoxic environments and plays a major role in global methane emissions. It is one of only two genera that can form methane from acetate dismutation and through participation in direct interspecies electron transfer (DIET) with exoelectrogens. Although Methanothrix is a significant member of many methanogenic communities, little is known about its physiology. In this study, transcriptomics helped to identify potential routes of electron transfer during DIET between Geobacter metallireducens and Methanothrix thermoacetophila. Additions of magnetite to cultures significantly enhanced growth by acetoclastic methanogenesis and by DIET, while granular activated carbon (GAC) amendments impaired growth. Transcriptomics suggested that the OmaF-OmbF-OmcF porin complex and the octaheme outer membrane c-type cytochrome encoded by Gmet_0930, were important for electron transport across the outer membrane of G. metallireducens during DIET with Mx. thermoacetophila. Clear differences in the metabolism of Mx. thermoacetophila when grown via DIET or acetate dismutation were not apparent. However, genes coding for proteins involved in carbon fixation, the sheath fiber protein MspA, and a surface-associated quinoprotein, SqpA, were highly expressed in all conditions. Expression of gas vesicle genes was significantly lower in DIET- than acetate-grown cells, possibly to facilitate better contact between membrane-associated redox proteins during DIET. These studies reveal potential electron transfer mechanisms utilized by both Geobacter and Methanothrix during DIET and provide important insights into the physiology of Methanothrix in anoxic environments. IMPORTANCE Methanothrix is a significant methane producer in a variety of methanogenic environments including soils and sediments as well as anaerobic digesters. Its abundance in these anoxic environments has mostly been attributed to its high affinity for acetate and its ability to grow by acetoclastic methanogenesis. However, Methanothrix species can also generate methane by directly accepting electrons from exoelectrogenic bacteria through direct interspecies electron transfer (DIET). Methane production through DIET is likely to further increase their contribution to methane production in natural and artificial environments. Therefore, acquiring a better understanding of DIET with Methanothrix will help shed light on ways to (i) minimize microbial methane production in natural terrestrial environments and (ii) maximize biogas formation by anaerobic digesters treating waste.
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Affiliation(s)
- Jinjie Zhou
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University , Shenzhen, Guangdong, China
- Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University , Shenzhen, Guangdong, China
- Department of Microbiology, University of Massachusetts-Amherst , Amherst, Massachusetts, USA
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University , Shenzhen, Guangdong, China
| | - Jessica A Smith
- Department of Microbiology, University of Massachusetts-Amherst , Amherst, Massachusetts, USA
- Department of Biomolecular Sciences, Central Connecticut State University , New Britain, Connecticut, USA
| | - Meng Li
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University , Shenzhen, Guangdong, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University , Shenzhen, Guangdong, China
| | - Dawn E Holmes
- Department of Microbiology, University of Massachusetts-Amherst , Amherst, Massachusetts, USA
- Department of Physical and Biological Science, Western New England University , Springfield, Massachusetts, USA
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Zhang D, Ke T, Xiu W, Ren C, Chen G, Lloyd JR, Bassil NM, Richards LA, Polya DA, Wang G, Guo H. Quantifying sulfidization and non-sulfidization in long-term in-situ microbial colonized As(V)-ferrihydrite coated sand columns: Insights into As mobility. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 858:160066. [PMID: 36356776 DOI: 10.1016/j.scitotenv.2022.160066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/30/2022] [Accepted: 11/04/2022] [Indexed: 06/16/2023]
Abstract
Sulfide-induced reduction (sulfidization) of arsenic (As)-bearing Fe(III) (oxyhydro)oxides may lead to As mobilization in aquifer systems. However, little is known about the relative contributions of sulfidization and non-sulfidization of Fe(III) (oxyhydro)oxides reduction to As mobilization. To address this issue, high As groundwater with low sulfide (LS) and high sulfide (HS) concentrations were pumped through As(V)-bearing ferrihydrite-coated sand columns (LS-column and HS-column, respectively) being settled within wells in the western Hetao Basin, China. Sulfidization of As(V)-bearing ferrihydrite was evidenced by the increase in dissolved Fe(II) and the presence of solid Fe(II) and elemental sulfur (S0) in both the columns. A conceptual model was built using accumulated S0 and Fe(II) produced in the columns to calculate the proportions of sulfidization-induced Fe(III) (oxyhydro)oxide reduction and non-sulfidization-induced Fe(III) (oxyhydro)oxide reduction. Fe(III) reduction via sulfidization occurred preferentially in the inlet ends (LS-column, 31 %; HS-column, 86 %), while Fe(III) reduction via non-sulfidization processes predominated in the outlet ends (LS-column, 96 %; HS-column, 86 %), and was attributed to the metabolism of genera associated with Fe(III) reduction (including Shewanella, Ferribacterium, and Desulfuromonas). Arsenic was mobilized in the columns via sulfidization and non-sulfidization processes. More As was released from the solid of the HS-column than that of the LS-column due to the higher intensity of sulfidization in the presence of higher concentrations of dissolved S(-II). Overall, this study highlights the sulfidization of As-bearing Fe(III) (oxyhydro)oxides as an important As-mobilizing pathway in complex As-Fe-S bio-hydrogeochemical networks.
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Affiliation(s)
- Di Zhang
- State Key Laboratory of Biogeology and Environmental Geology and MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Tiantian Ke
- State Key Laboratory of Biogeology and Environmental Geology and MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Wei Xiu
- State Key Laboratory of Biogeology and Environmental Geology and MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, PR China; Institute of Earth sciences, China University of Geosciences (Beijing), Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China; Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom.
| | - Cui Ren
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Guangyu Chen
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Jonathan R Lloyd
- Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Naji M Bassil
- Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Laura A Richards
- Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - David A Polya
- Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Guangcai Wang
- State Key Laboratory of Biogeology and Environmental Geology and MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Huaming Guo
- State Key Laboratory of Biogeology and Environmental Geology and MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
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Gao Z, Bai Y, Su J, Ali A, Li K, Hu R, Wang Y. Manganese redox cycling in immobilized bioreactors for simultaneous removal of nitrate and 17β-estradiol: Performance, mechanisms and community assembly potential. BIORESOURCE TECHNOLOGY 2023; 367:128282. [PMID: 36368483 DOI: 10.1016/j.biortech.2022.128282] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 10/31/2022] [Accepted: 11/02/2022] [Indexed: 06/16/2023]
Abstract
The application of bio-manganese (Mn) redox cycling for continuous removal of contaminants provides promise for addressing coexisting contaminants in groundwater, however, the feasibility of constructing Mn redox cycling system (MCS) through community assembly remains to be elucidated. In this study, Mn-reducing strain MFG10 and Mn-oxidizing strain MFQ7 synergistically removed 94.67 % of 17β-estradiol (E2) within 12 h. Analysis of potential variations in Mn oxides suggested that MCS accelerated the production of reactive oxygen species (ROS) and Mn(III), which interacted to promote E2 removal. After continuous operation of the Mn ore-based immobilized bioreactor for 270 days, the experimental group (EG) achieved average removal efficiencies of 89.63 % and 97.57 % for NO3--N and E2, respectively. High-throughput sequencing results revealed complex symbiotic relationships in EG. Community assembly significantly enhanced the metabolic and physiological activity of the bioreactor, which promoting the expression of core functions including nitrogen metabolism, Mn cycling and organic matter resistance.
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Affiliation(s)
- Zhihong Gao
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Yihan Bai
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Junfeng Su
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
| | - Amjad Ali
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Kai Li
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Ruizhu Hu
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Yue Wang
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
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Guo J, Jiang J, Peng Z, Zhong Y, Jiang Y, Jiang Z, Hu Y, Dong Y, Shi L. Global occurrence of the bacteria with capability for extracellular reduction of iodate. Front Microbiol 2022; 13:1070601. [PMID: 36504819 PMCID: PMC9732548 DOI: 10.3389/fmicb.2022.1070601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 11/11/2022] [Indexed: 11/27/2022] Open
Abstract
The γ-proteobacterium Shewanella oneidensis MR-1 reduces iodate to iodide extracellularly. Both dmsEFAB and mtrCAB gene clusters are involved in extracellular reduction of iodate by S. oneidensis MR-1. DmsEFAB reduces iodate to hypoiodous acid and hydrogen peroxide (H2O2). Subsequently, H2O2 is reduced by MtrCAB to facilitate DmsEFAB-mediated extracellular reduction of iodate. To investigate the distribution of bacteria with the capability for extracellular reduction of iodate, bacterial genomes were systematically searched for both dmsEFAB and mtrCAB gene clusters. The dmsEFAB and mtrCAB gene clusters were found in three Ferrimonas and 26 Shewanella species. Coexistence of both dmsEFAB and mtrCAB gene clusters in these bacteria suggests their potentials for extracellular reduction of iodate. Further analyses demonstrated that these bacteria were isolated from a variety of ecosystems, including the lakes, rivers, and subsurface rocks in East and Southeast Asia, North Africa, and North America. Importantly, most of the bacteria with both dmsEFAB and mtrCAB gene clusters were found in different marine environments, which ranged from the Arctic Ocean to Antarctic coastal marine environments as well as from the Atlantic Ocean to the Indian and Pacific Oceans. Widespread distribution of the bacteria with capability for extracellular reduction of iodate around the world suggests their significant importance in global biogeochemical cycling of iodine. The genetic organization of dmsEFAB and mtrCAB gene clusters also varied substantially. The identified mtrCAB gene clusters often contained additional genes for multiheme c-type cytochromes. The numbers of dmsEFAB gene cluster detected in a given bacterial genome ranged from one to six. In latter, duplications of dmsEFAB gene clusters occurred. These results suggest different paths for these bacteria to acquire their capability for extracellular reduction of iodate.
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Affiliation(s)
- Jinzhi Guo
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Jie Jiang
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Zhaofeng Peng
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China,*Correspondence: Zhaofeng Peng,
| | - Yuhong Zhong
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Yongguang Jiang
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Zhou Jiang
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China,State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
| | - Yidan Hu
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Yiran Dong
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China,State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China,Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, China University of Geosciences, Wuhan, China,State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, China
| | - Liang Shi
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China,State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China,Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, China University of Geosciences, Wuhan, China,State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, China,*Correspondence: Zhaofeng Peng,
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8
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Quinones: More Than Electron Shuttles. Res Microbiol 2022; 173:103953. [DOI: 10.1016/j.resmic.2022.103953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 04/08/2022] [Accepted: 04/14/2022] [Indexed: 11/21/2022]
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9
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Zhu TT, Cheng ZH, Yu SS, Li WW, Liu DF, Yu HQ. Unexpected role of electron-transfer hub in direct degradation of pollutants by exoelectrogenic bacteria. Environ Microbiol 2022; 24:1838-1848. [PMID: 35170205 DOI: 10.1111/1462-2920.15939] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 01/28/2022] [Accepted: 02/11/2022] [Indexed: 11/25/2022]
Abstract
Exoelectrogenic bacteria (EEB) are capable of anaerobic respiration with diverse extracellular electron acceptors including insoluble minerals, electrodes and flavins, but the detailed electron transfer pathways and reaction mechanisms remain elusive. Here, we discover that CymA, which is usually considered to solely serve as an inner-membrane electron transfer hub in Shewanella oneidensis MR-1 (a model EEB), might also function as a reductase for direct reducing diverse nitroaromatic compounds (e.g., 2,4-dichloronitrobenzene) and azo dyes. Such a process can be accelerated by dosing anthraquinone-2,6-disulfonate. The CymA-based reduction pathways in S. oneidensis MR-1 for different contaminants could be functionally reconstructed and strengthened in Escherichia coli. The direct reduction of lowly polar contaminants by quinol oxidases like CymA homologs might be universal in diverse microbes. This work offers new insights into the pollutant reduction mechanisms of EEB and unveils a new function of CymA to act as a terminal reductase. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Ting-Ting Zhu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China
| | - Zhou-Hua Cheng
- School of Life Sciences, University of Science and Technology of China, Hefei, 230026, China
| | - Sheng-Song Yu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China
| | - Wen-Wei Li
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China.,University of Science and Technology of China-City University of Hong Kong Joint Advanced Research Center, Suzhou Institute for Advance Research of USTC, Suzhou, 215123, China
| | - Dong-Feng Liu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China.,Anhui Key Laboratory of Sewage Purification and Ecological Rehabilitation Materials, Hefei, 230601, China
| | - Han-Qing Yu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China
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Clarke TA. Plugging into bacterial nanowires: a comparison of model electrogenic organisms. Curr Opin Microbiol 2022; 66:56-62. [PMID: 34999354 DOI: 10.1016/j.mib.2021.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 12/20/2022]
Abstract
Extracellular electron transport (EET) is an important metabolic process used by many bacteria to remove excess electrons generated through cellular metabolism. However, there is still limited understanding about how the molecular mechanisms used to export electrons impact cellular metabolism. Here the EET pathways of two of the best-studied electrogenic organisms, Shewanella oneidensis and Geobacter sulferreducens, are described. Both organisms have superficially similar overall EET routes, but differ in the mechanisms used to oxidise menaquinol, transfer electrons across the outer membrane and reduce extracellular substrates. These mechanistic differences substantially impact both substrate choice and bacterial lifestyle.
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Affiliation(s)
- Thomas Andrew Clarke
- School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, United Kingdom.
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11
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Xiu W, Ke T, Lloyd JR, Shen J, Bassil NM, Song H, Polya DA, Zhao Y, Guo H. Understanding Microbial Arsenic-Mobilization in Multiple Aquifers: Insight from DNA and RNA Analyses. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:15181-15195. [PMID: 34706533 DOI: 10.1021/acs.est.1c04117] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Biogeochemical processes critically control the groundwater arsenic (As) enrichment; however, the key active As-mobilizing biogeochemical processes and associated microbes in high dissolved As and sulfate aquifers are poorly understood. To address this issue, the groundwater-sediment geochemistry, total and active microbial communities, and their potential functions in the groundwater-sediment microbiota from the western Hetao basin were determined using 16S rRNA gene (rDNA) and associated 16S rRNA (rRNA) sequencing. The relative abundances of either sediment or groundwater total and active microbial communities were positively correlated. Interestingly, groundwater active microbial communities were mainly associated with ammonium and sulfide, while sediment active communities were highly related to water-extractable nitrate. Both sediment-sourced and groundwater-sourced active microorganisms (rRNA/rDNA ratios > 1) noted Fe(III)-reducers (induced by ammonium oxidation) and As(V)-reducers, emphasizing the As mobilization via Fe(III) and/or As(V) reduction. Moreover, active cryptic sulfur cycling between groundwater and sediments was implicated in affecting As mobilization. Sediment-sourced active microorganisms were potentially involved in anaerobic pyrite oxidation (driven by denitrification), while groundwater-sourced organisms were associated with sulfur disproportionation and sulfate reduction. This study provides an extended whole-picture concept model of active As-N-S-Fe biogeochemical processes affecting As mobilization in high dissolved As and sulfate aquifers.
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Affiliation(s)
- Wei Xiu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, P.R. China
- Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, P.R. China
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, P.R. China
| | - Tiantian Ke
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, P.R. China
| | - Jonathan R Lloyd
- Williamson Research Centre for Molecular Environmental Science, School of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Jiaxing Shen
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, P.R. China
| | - Naji M Bassil
- Williamson Research Centre for Molecular Environmental Science, School of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Hokyung Song
- Williamson Research Centre for Molecular Environmental Science, School of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - David A Polya
- Williamson Research Centre for Molecular Environmental Science, School of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Yi Zhao
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, P.R. China
| | - Huaming Guo
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, P.R. China
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, P.R. China
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12
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Evidence for Horizontal and Vertical Transmission of Mtr-Mediated Extracellular Electron Transfer among the Bacteria. mBio 2021; 13:e0290421. [PMID: 35100867 PMCID: PMC8805035 DOI: 10.1128/mbio.02904-21] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Some bacteria and archaea have evolved the means to use extracellular electron donors and acceptors for energy metabolism, a phenomenon broadly known as extracellular electron transfer (EET). One such EET mechanism is the transmembrane electron conduit MtrCAB, which has been shown to transfer electrons derived from metabolic substrates to electron acceptors, like Fe(III) and Mn(IV) oxides, outside the cell. Although most studies of MtrCAB-mediated EET have been conducted in Shewanella oneidensis MR-1, recent investigations in Vibrio and Aeromonas species have revealed that the electron-donating proteins that support MtrCAB in Shewanella are not as representative as previously thought. This begs the question of how widespread the capacity for MtrCAB-mediated EET is, the changes it has accrued in different lineages, and where these lineages persist today. Here, we employed a phylogenetic and comparative genomics approach to identify the MtrCAB system across all domains of life. We found mtrCAB in the genomes of numerous diverse Bacteria from a wide range of environments, and the patterns therein strongly suggest that mtrCAB was distributed through both horizontal and subsequent vertical transmission, and with some cases indicating downstream modular diversification of both its core and accessory components. Our data point to an emerging evolutionary story about metal-oxidizing and -reducing metabolism, demonstrates that this capacity for EET has broad relevance to a diversity of taxa and the biogeochemical cycles they drive, and lays the foundation for further studies to shed light on how this mechanism may have coevolved with Earth's redox landscape. IMPORTANCE While many metabolisms make use of soluble, cell-permeable substrates like oxygen or hydrogen, there are other substrates, like iron or manganese, that cannot be brought into the cell. Some bacteria and archaea have evolved the means to directly "plug in" to such environmental electron reservoirs in a process known as extracellular electron transfer (EET), making them powerful agents of biogeochemical change and promising vehicles for bioremediation and alternative energy. Yet the diversity, distribution, and evolution of EET mechanisms are poorly constrained. Here, we present findings showing that the genes encoding one such EET system (mtrCAB) are present in a broad diversity of bacteria found in a wide range of environments, emphasizing the ubiquity and potential impact of EET in our biosphere. Our results suggest that these genes have been disseminated largely through horizontal transfer, and the changes they have accrued in these lineages potentially reflect adaptations to changing environments.
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Valenzuela EI, Cervantes FJ. The role of humic substances in mitigating greenhouse gases emissions: Current knowledge and research gaps. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 750:141677. [PMID: 33182214 DOI: 10.1016/j.scitotenv.2020.141677] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 08/10/2020] [Accepted: 08/11/2020] [Indexed: 06/11/2023]
Abstract
Humic substances (HS) constitute a highly transformed fraction of natural organic matter (NOM) with a heterogeneous structure, which is rich in electron-transferring functional moieties. Because of this feature, HS display a versatile reactivity with a diversity of environmentally relevant organic and inorganic compounds either by abiotic or microbial processes. Consequently, extensive research has been conducted related to the potential of HS to drive relevant processes in bio-engineered systems, as well as in the biogeochemical cycling of key elements in natural environments. Nevertheless, the increase in the number of reports examining the relationship between HS and the microorganisms related to the production and consumption of greenhouse gases (GHG), the main drivers of global warming, has just emerged in the last years. In this paper, we discuss the importance of HS, and their analogous redox-active organic molecules (RAOM), on controlling the emission of three of the most relevant GHG due to their tight relationship with microbial activity, their abundance on the Earth's atmosphere, and their important global warming potentials: carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). The current knowledge gaps concerning the microbial component, on-site occurrence, and environmental constraints affecting these HS-mediated processes are provided. Furthermore, strategies involving the metabolic traits that GHG-consuming/HS-reducing and -oxidizing microbes display for the development of environmental engineered processes are also discussed.
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Affiliation(s)
- Edgardo I Valenzuela
- División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico.
| | - Francisco J Cervantes
- Laboratory for Research on Advanced Processes for Water Treatment, Engineering Institute, Campus Juriquilla, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico.
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14
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Torres-Rojas F, Muñoz D, Tapia N, Canales C, Vargas IT. Bioelectrochemical chlorate reduction by Dechloromonas agitata CKB. BIORESOURCE TECHNOLOGY 2020; 315:123818. [PMID: 32688253 DOI: 10.1016/j.biortech.2020.123818] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/05/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
Chlorate has been described as an emerging pollutant that compromises water sources. In this study, bioelectrochemical reactors (BERs) using Dechloromonas agitata CKB, were evaluated as a sustainable alternative for chlorate removal. BERs were operated under flow-recirculation and batch modes with an applied cell-voltage of 0.44 V over a resistance of 1 kΩ. Results show chlorate removal up to 607.288 mg/L. After 115 days, scanning electron microscopy showed biofilm development over the electrodes, and electrochemical impedance spectroscopy confirmed the biocatalytic effect of CKB. The theoretical chlorate bioreduction potential (ε° = 0.792 V) was proven, and a kinetic study indicated that 6 electrons were involved in the reduction mechanism. Finally, a hypothetical bioelectrochemical mechanism for chlorate reduction in a BER was proposed. This research expands upon current knowledge of novel electrochemically active microorganisms and widens the scope of BER applications for chlorate removal.
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Affiliation(s)
- Felipe Torres-Rojas
- Departamento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile
| | - Diana Muñoz
- Departamento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile; Centro de Desarrollo Urbano Sustentable (CEDEUS), Chile
| | - Natalia Tapia
- Departamento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile; Centro de Desarrollo Urbano Sustentable (CEDEUS), Chile
| | - Camila Canales
- Science Institute & Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, University of Iceland, VR-III, Hjardarhaga 2, 107 Reykjavík, Iceland
| | - Ignacio T Vargas
- Departamento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile; Centro de Desarrollo Urbano Sustentable (CEDEUS), Chile.
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15
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A Hybrid Extracellular Electron Transfer Pathway Enhances the Survival of Vibrio natriegens. Appl Environ Microbiol 2020; 86:AEM.01253-20. [PMID: 32737131 DOI: 10.1128/aem.01253-20] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/28/2020] [Indexed: 02/06/2023] Open
Abstract
Vibrio natriegens is the fastest-growing microorganism discovered to date, making it a useful model for biotechnology and basic research. While it is recognized for its rapid aerobic metabolism, less is known about anaerobic adaptations in V. natriegens or how the organism survives when oxygen is limited. Here, we describe and characterize extracellular electron transfer (EET) in V. natriegens, a metabolism that requires movement of electrons across protective cellular barriers to reach the extracellular space. V. natriegens performs extracellular electron transfer under fermentative conditions with gluconate, glucosamine, and pyruvate. We characterized a pathway in V. natriegens that requires CymA, PdsA, and MtrCAB for Fe(III) citrate and Fe(III) oxide reduction, which represents a hybrid of strategies previously discovered in Shewanella and Aeromonas Expression of these V. natriegens genes functionally complemented Shewanella oneidensis mutants. Phylogenetic analysis of the inner membrane quinol dehydrogenases CymA and NapC in gammaproteobacteria suggests that CymA from Shewanella diverged from Vibrionaceae CymA and NapC. Analysis of sequenced Vibrionaceae revealed that the genetic potential to perform EET is conserved in some members of the Harveyi and Vulnificus clades but is more variable in other clades. We provide evidence that EET enhances anaerobic survival of V. natriegens, which may be the primary physiological function for EET in Vibrionaceae IMPORTANCE Bacteria from the genus Vibrio occupy a variety of marine and brackish niches with fluctuating nutrient and energy sources. When oxygen is limited, fermentation or alternative respiration pathways must be used to conserve energy. In sedimentary environments, insoluble oxide minerals (primarily iron and manganese) are able to serve as electron acceptors for anaerobic respiration by microorganisms capable of extracellular electron transfer, a metabolism that enables the use of these insoluble substrates. Here, we identify the mechanism for extracellular electron transfer in Vibrio natriegens, which uses a combination of strategies previously identified in Shewanella and Aeromonas We show that extracellular electron transfer enhanced survival of V. natriegens under fermentative conditions, which may be a generalized strategy among Vibrio spp. predicted to have this metabolism.
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16
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Inoue M, Izumihara H, Fukuyama Y, Omae K, Yoshida T, Sako Y. Carbon monoxide-dependent transcriptional changes in a thermophilic, carbon monoxide-utilizing, hydrogen-evolving bacterium Calderihabitans maritimus KKC1 revealed by transcriptomic analysis. Extremophiles 2020; 24:551-564. [PMID: 32388815 PMCID: PMC7306483 DOI: 10.1007/s00792-020-01175-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 04/27/2020] [Indexed: 11/30/2022]
Abstract
Calderihabitans maritimus KKC1 is a thermophilic, carbon monoxide (CO)-utilizing, hydrogen-evolving bacterium that harbors seven cooS genes for anaerobic CO dehydrogenases and six hyd genes for [NiFe] hydrogenases and capable of using a variety of electron acceptors coupled to CO oxidation. To understand the relationships among these unique features and the transcriptional adaptation of the organism to CO, we performed a transcriptome analysis of C. maritimus KKC1 grown under 100% CO and N2 conditions. Of its 3114 genes, 58 and 32 genes were significantly upregulated and downregulated in the presence of CO, respectively. A cooS–ech gene cluster, an “orphan” cooS gene, and bidirectional hyd genes were upregulated under CO, whereas hydrogen-uptake hyd genes were downregulated. Transcriptional changes in anaerobic respiratory genes supported the broad usage of electron acceptors in C. maritimus KKC1 under CO metabolism. Overall, the majority of the differentially expressed genes were oxidoreductase-like genes, suggesting metabolic adaptation to the cellular redox change upon CO oxidation. Moreover, our results suggest a transcriptional response mechanism to CO that involves multiple transcription factors, as well as a CO-responsive transcriptional activator (CooA). Our findings shed light on the diverse mechanisms for transcriptional and metabolic adaptations to CO in CO-utilizing and hydrogen-evolving bacteria.
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Affiliation(s)
- Masao Inoue
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Hikaru Izumihara
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Yuto Fukuyama
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Kimiho Omae
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Takashi Yoshida
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Yoshihiko Sako
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan.
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17
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Zhu W, Yao M, Gao H, Wen H, Zhao X, Zhang J, Bai H. Enhanced extracellular electron transfer between Shewanella putrefaciens and carbon felt electrode modified by bio-reduced graphene oxide. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 691:1089-1097. [PMID: 31466191 DOI: 10.1016/j.scitotenv.2019.07.104] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Revised: 07/07/2019] [Accepted: 07/07/2019] [Indexed: 06/10/2023]
Abstract
Extracellular electron transfer (EET) is a governing factor for the electrochemical performance of a bioelectrochemical system (BES) such as the microbial fuel cell (MFC). Herein, an in situ method to fabricate a bio-reduced graphene oxide (GO) (br-GO) modified carbon felt electrode to increase EET was developed. GO (0.5mgmL-1) was spiked into the anode chamber in a three-electrode BES and was transformed to br-GO with a self-assembled three-dimensional (3D) structure. The response of the br-GO modified electrode potential to the attached population of Shewanella putrefaciens increased from 0.071V to 0.517V (vs Ag/AgCl). Meanwhile, br-GO modification resulted a significant enhancement in the total amount of extracellular electrons transferred between the modified electrode and microbe. The process of br-GO modification lowered the charge transfer resistance of the electrode and enhanced the EET. The modified electrode was further employed as an anode in the MFC, and consequently, the power density of the MFC was significantly enhanced. The current study not only gives a simple and effective way for improving the EET with br-GO fabrication, but also provides a strategy to enhance the power density of the MFC.
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Affiliation(s)
- Weihuang Zhu
- Key Laboratory of Northwest Water Resources, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
| | - Min Yao
- Key Laboratory of Northwest Water Resources, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Haoxiang Gao
- Key Laboratory of Northwest Water Resources, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Hu Wen
- Key Laboratory of Northwest Water Resources, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Xiaoli Zhao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Jianfeng Zhang
- Key Laboratory of Northwest Water Resources, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Huiling Bai
- College of literature, Xi'an University of Architecture and Technology, Xi'an 710055, China
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Abstract
Cable bacteria of the family Desulfobulbaceae form centimeter-long filaments comprising thousands of cells. They occur worldwide in the surface of aquatic sediments, where they connect sulfide oxidation with oxygen or nitrate reduction via long-distance electron transport. In the absence of pure cultures, we used single-filament genomics and metagenomics to retrieve draft genomes of 3 marine Candidatus Electrothrix and 1 freshwater Ca. Electronema species. These genomes contain >50% unknown genes but still share their core genomic makeup with sulfate-reducing and sulfur-disproportionating Desulfobulbaceae, with few core genes lost and 212 unique genes (from 197 gene families) conserved among cable bacteria. Last common ancestor analysis indicates gene divergence and lateral gene transfer as equally important origins of these unique genes. With support from metaproteomics of a Ca. Electronema enrichment, the genomes suggest that cable bacteria oxidize sulfide by reversing the canonical sulfate reduction pathway and fix CO2 using the Wood-Ljungdahl pathway. Cable bacteria show limited organotrophic potential, may assimilate smaller organic acids and alcohols, fix N2, and synthesize polyphosphates and polyglucose as storage compounds; several of these traits were confirmed by cell-level experimental analyses. We propose a model for electron flow from sulfide to oxygen that involves periplasmic cytochromes, yet-unidentified conductive periplasmic fibers, and periplasmic oxygen reduction. This model proposes that an active cable bacterium gains energy in the anodic, sulfide-oxidizing cells, whereas cells in the oxic zone flare off electrons through intense cathodic oxygen respiration without energy conservation; this peculiar form of multicellularity seems unparalleled in the microbial world.
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Paquete CM, Rusconi G, Silva AV, Soares R, Louro RO. A brief survey of the "cytochromome". Adv Microb Physiol 2019; 75:69-135. [PMID: 31655743 DOI: 10.1016/bs.ampbs.2019.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Multihaem cytochromes c are widespread in nature where they perform numerous roles in diverse anaerobic metabolic pathways. This is achieved in two ways: multihaem cytochromes c display a remarkable diversity of ways to organize multiple hemes within the protein frame; and the hemes possess an intrinsic reactive versatility derived from diverse spin, redox and coordination states. Here we provide a brief survey of multihaem cytochromes c that have been characterized in the context of their metabolic role. The contribution of multihaem cytochromes c to dissimilatory pathways handling metallic minerals, nitrogen compounds, sulfur compounds, organic compounds and phototrophism are described. This aims to set the stage for the further exploration of the vast unknown "cytochromome" that can be anticipated from genomic databases.
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