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Yoon Y, Aziz AA, Chang IS, Kim B. Prevalence of Escherichia coli in electrogenic biofilm on activated carbon in microbial fuel cell. Appl Microbiol Biotechnol 2024; 108:52. [PMID: 38183478 DOI: 10.1007/s00253-023-12829-1] [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: 03/29/2023] [Revised: 10/11/2023] [Accepted: 11/04/2023] [Indexed: 01/08/2024]
Abstract
For a better understanding of the distribution of depth-dependent electrochemically active bacteria at in the anode zone, a customized system in a microbial fuel cell (MFC) packed with granular activated carbon (GAC) was developed and subsequently optimized via electrochemical tests. The constructed MFC system was sequentially operated using two types of matrice solutions: artificially controlled compositions (i.e., artificial wastewater, AW) and solutions obtained directly from actual sewage-treating municipal plants (i.e., municipal wastewater, MW). Notably, significant difference(s) of system efficiencies between AW or MW matrices were observed via performance tests, in that the electricity production capacity under MW matrices is < 25% that of the AW matrices. Interestingly, species of Escherichia coli (E. coli) sampled from the GAC bed (P1: deeper region in GAC bed, P2: shallow region of GAC near electrolytes) exhibited an average relative abundance of 75 to 90% in AW and a relative abundance of approximately 10% in MW, while a lower relative abundance of E. coli was found in both the AW and MW anolyte samples (L). Moreover, similar bacterial communities were identified in samples P1 and P2 for both the AW and MW solutions, indicating a comparable distribution of bacterial communities over the anode area. These results provide new insights into E. coli contribution in power production for the GAC-packed MFC systems (i.e., despite the low contents of Geobacter (> 8%) and Shewanella (> 1%)) for future applications in sustainable energy research. KEY POINTS: • A microbial community analysis for depth-dependence in biofilm was developed. • The system was operated with two matrices; electrochemical performance was assessed. • E. coli spp. was distinctly found in anode zone layers composed of activated carbon.
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Affiliation(s)
- Younggun Yoon
- SELS Center, Division of Biotechnology, College of Environmental and Bioresource Sciences, Jeonbuk National University, Iksan, Jeonbuk, 54596, South Korea
| | - Azilah Abd Aziz
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-Ro, Buk-Gu, Gwangju, 61005, South Korea
| | - In Seop Chang
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-Ro, Buk-Gu, Gwangju, 61005, South Korea.
| | - Bongkyu Kim
- SELS Center, Division of Biotechnology, College of Environmental and Bioresource Sciences, Jeonbuk National University, Iksan, Jeonbuk, 54596, South Korea.
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Li Y, Cao M, Gupta VK, Wang Y. Metabolic engineering strategies to enable microbial electrosynthesis utilization of CO 2: recent progress and challenges. Crit Rev Biotechnol 2024; 44:352-372. [PMID: 36775662 DOI: 10.1080/07388551.2023.2167065] [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: 06/04/2022] [Revised: 10/17/2022] [Accepted: 12/08/2022] [Indexed: 02/14/2023]
Abstract
Microbial electrosynthesis (MES) is a promising technology that mainly utilizes microbial cells to convert CO2 into value-added chemicals using electrons provided by the cathode. However, the low electron transfer rate is a solid bottleneck hindering the further application of MES. Thus, as an effective strategy, genetic tools play a key role in MES for enhancing the electron transfer rate and diversity of production. We describe a set of genetic strategies based on fundamental characteristics and current successes and discuss their functional mechanisms in driving microbial electrocatalytic reactions to fully comprehend the roles and uses of genetic tools in MES. This paper also analyzes the process of nanomaterial application in extracellular electron transfer (EET). It provides a technique that combines nanomaterials and genetic tools to increase MES efficiency, because nanoparticles have a role in the production of functional genes in EET although genetic tools can subvert MES, it still has issues with difficult transformation and low expression levels. Genetic tools remain one of the most promising future strategies for advancing the MES process despite these challenges.
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Affiliation(s)
- Yixin Li
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Key Laboratory for Chemical Biology of Fujian Province, Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen, China
| | - Mingfeng Cao
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Key Laboratory for Chemical Biology of Fujian Province, Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen, China
- Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen, China
| | - Vijai Kumar Gupta
- Biorefining and Advanced Materials Research Center, SRUC, Edinburgh, UK
| | - Yuanpeng Wang
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Key Laboratory for Chemical Biology of Fujian Province, Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen, China
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3
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Fang Y, Yang G, Wu X, Lin C, Qin B, Zhuang L. A genetic engineering strategy to enhance outer membrane vesicle-mediated extracellular electron transfer of Geobacter sulfurreducens. Biosens Bioelectron 2024; 250:116068. [PMID: 38280298 DOI: 10.1016/j.bios.2024.116068] [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: 12/02/2023] [Revised: 01/21/2024] [Accepted: 01/22/2024] [Indexed: 01/29/2024]
Abstract
Bioelectrochemical systems (BESs) are unique devices that harness the metabolic activity of electroactive microorganisms (EAMs) to convert chemical energy stored in organic substrates into electrical energy. Enhancing electron transfer efficiency between EAMs and electrodes is the key to practical implementation of BESs. Considering the role of outer membrane vesicles (OMVs) in mediating electron transfer of EAMs, a genetic engineering strategy to achieve OMVs overproduction was explored to enhance electron transfer efficiency and the underlying mechanisms were investigated. This study constructed a mutant strain of Geobacter sulfurreducens that lacked the ompA gene encoding an outer membrane protein. Experimental results showed that the mutant strain produced more OMVs and possessed higher electron transfer efficiency in Fe(III) reduction, dye degradation and current generation in BESs than the wild-type strain. More cargoes such as c-type cytochromes, functional proteins, eDNA, polysaccharides and signaling molecules that might be favorable for electron transfer and biofilm formation were found in OMVs produced by ompA-deficient anodic biofilm, which possibly contributed to the improved electron transfer efficiency of ompA-deficient biofilm. The results indicate that overproduction of OMVs in EAMs might be a potential strategy to enhance BESs performance.
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Affiliation(s)
- Yanlun Fang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China
| | - Guiqin Yang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China.
| | - Xian Wu
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China
| | - Canfen Lin
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China
| | - Baoli Qin
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China
| | - Li Zhuang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China.
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Li Y, Liu Y, Guo D, Dong H. Differential degradation of petroleum hydrocarbons by Shewanella putrefaciens under aerobic and anaerobic conditions. Front Microbiol 2024; 15:1389954. [PMID: 38659987 PMCID: PMC11040095 DOI: 10.3389/fmicb.2024.1389954] [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: 02/22/2024] [Accepted: 03/27/2024] [Indexed: 04/26/2024] Open
Abstract
The complexity of crude oil composition, combined with the fluctuating oxygen level in contaminated environments, poses challenges for the bioremediation of oil pollutants, because of compound-specific microbial degradation of petroleum hydrocarbons under certain conditions. As a result, facultative bacteria capable of breaking down petroleum hydrocarbons under both aerobic and anaerobic conditions are presumably effective, however, this hypothesis has not been directly tested. In the current investigation, Shewanella putrefaciens CN32, a facultative anaerobic bacterium, was used to degrade petroleum hydrocarbons aerobically (using O2 as an electron acceptor) and anaerobically (using Fe(III) as an electron acceptor). Under aerobic conditions, CN32 degraded more saturates (65.65 ± 0.01%) than aromatics (43.86 ± 0.03%), with the following order of degradation: dibenzofurans > n-alkanes > biphenyls > fluorenes > naphthalenes > alkylcyclohexanes > dibenzothiophenes > phenanthrenes. In contrast, under anaerobic conditions, CN32 exhibited a higher degradation of aromatics (53.94 ± 0.02%) than saturates (23.36 ± 0.01%), with the following order of degradation: dibenzofurans > fluorenes > biphenyls > naphthalenes > dibenzothiophenes > phenanthrenes > n-alkanes > alkylcyclohexanes. The upregulation of 4-hydroxy-3-polyprenylbenzoate decarboxylase (ubiD), which plays a crucial role in breaking down resistant aromatic compounds, was correlated with the anaerobic degradation of aromatics. At the molecular level, CN32 exhibited a higher efficiency in degrading n-alkanes with low and high carbon numbers relative to those with medium carbon chain lengths. In addition, the degradation of polycyclic aromatic hydrocarbons (PAHs) under both aerobic and anaerobic conditions became increasingly difficult with increased numbers of benzene rings and methyl groups. This study offers a potential solution for the development of targeted remediation of pollutants under oscillating redox conditions.
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Affiliation(s)
- Yang Li
- Center for Geomicrobiology and Biogeochemistry Research, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, China
- School of Earth Sciences and Resources, China University of Geosciences, Beijing, China
| | - Yuan Liu
- Center for Geomicrobiology and Biogeochemistry Research, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, China
- School of Earth Sciences and Resources, China University of Geosciences, Beijing, China
| | - Dongyi Guo
- Center for Geomicrobiology and Biogeochemistry Research, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, China
| | - Hailiang Dong
- Center for Geomicrobiology and Biogeochemistry Research, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, China
- School of Earth Sciences and Resources, China University of Geosciences, Beijing, China
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Long X, Tokunou Y, Okamoto A. Mechano-control of Extracellular Electron Transport Rate via Modification of Inter-heme Coupling in Bacterial Surface Cytochrome. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:7421-7430. [PMID: 37079493 DOI: 10.1021/acs.est.3c00601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Bacterial outer-membrane multi-heme cytochromes (OMCs) mediate extracellular electron transport (EET). While heme alignment dictates the rate of EET, control of inter-heme coupling in a single OMC remains challenging, especially in intact cells. Given that OMCs diffuse and collide without aggregation on the cell surface, the overexpression of OMCs could increase such mechanical stress to impact the OMCs' protein structure. Here, the heme coupling is modified via mechanical interactions among OMCs by controlling their concentrations. Employment of whole-cell circular dichroism (CD) spectra of genetically engineered Escherichia coli reveals that the OMC concentration significantly impacts the molar CD and redox property of OMCs, resulting in a 4-fold change of microbial current production. The overexpression of OMCs increased the conductive current across the biofilm on an interdigitated electrode, indicating that a higher concentration of OMCs causes more lateral inter-protein electron hopping via collision on the cell surface. The present study would open a novel strategy to increase microbial current production by mechanically enhancing the inter-heme coupling.
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Affiliation(s)
- Xizi Long
- School of the Key Laboratory of Typical Environmental Pollution and Health Hazards of Hunan Province, School of Basic Medicine, School of Public Health, Hengyang Medical School, University of South China, Hengyang 421001, China
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Yoshihide Tokunou
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 Japan
| | - Akihiro Okamoto
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 13 West 8, Kitaku, Sapporo, Hokkaido 060-8628, Japan
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Zhao J, Li F, Kong S, Chen T, Song H, Wang Z. Elongated Riboflavin-Producing Shewanella oneidensis in a Hybrid Biofilm Boosts Extracellular Electron Transfer. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2206622. [PMID: 36710254 PMCID: PMC10037984 DOI: 10.1002/advs.202206622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 01/05/2023] [Indexed: 06/18/2023]
Abstract
Shewanella oneidensis is able to carry out extracellular electron transfer (EET), although its EET efficiency is largely limited by low flavin concentrations, poor biofilm forming-ability, and weak biofilm conductivity. After identifying an important role for riboflavin (RF) in EET via in vitro experiments, the synthesis of RF is directed to 837.74 ± 11.42 µm in S. oneidensis. Molecular dynamics simulation reveals RF as a cofactor that binds strongly to the outer membrane cytochrome MtrC, which is correspondingly further overexpressed to enhance EET. Then the cell division inhibitor sulA, which dramatically enhanced the thickness and biomass of biofilm increased by 155% and 77%, respectively, is overexpressed. To reduce reaction overpotential due to biofilm thickness, a spider-web-like hybrid biofilm comprising RF, multiwalled carbon nanotubes (MWCNTs), and graphene oxide (GO) with adsorption-optimized elongated S. oneidensis, achieve a 77.83-fold increase in power (3736 mW m-2 ) relative to MR-1 and dramatically reduce the charge-transfer resistance and boosted biofilm electroactivity. This work provides an elegant paradigm to boost EET based on a synthetic biology strategy and materials science strategy, opens up further opportunities for other electrogenic bacteria.
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Affiliation(s)
- Juntao Zhao
- Frontier Science Center for Synthetic BiologyTianjin UniversityTianjin300072P. R. China
- Key Laboratory of Systems Bioengineering (Ministry of Education)Tianjin UniversityTianjin300072P. R. China
- School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072P. R. China
| | - Feng Li
- Frontier Science Center for Synthetic BiologyTianjin UniversityTianjin300072P. R. China
- Key Laboratory of Systems Bioengineering (Ministry of Education)Tianjin UniversityTianjin300072P. R. China
- School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072P. R. China
| | - Shutian Kong
- Frontier Science Center for Synthetic BiologyTianjin UniversityTianjin300072P. R. China
- Key Laboratory of Systems Bioengineering (Ministry of Education)Tianjin UniversityTianjin300072P. R. China
- School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072P. R. China
| | - Tao Chen
- Frontier Science Center for Synthetic BiologyTianjin UniversityTianjin300072P. R. China
- Key Laboratory of Systems Bioengineering (Ministry of Education)Tianjin UniversityTianjin300072P. R. China
- School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072P. R. China
| | - Hao Song
- Frontier Science Center for Synthetic BiologyTianjin UniversityTianjin300072P. R. China
- Key Laboratory of Systems Bioengineering (Ministry of Education)Tianjin UniversityTianjin300072P. R. China
- School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072P. R. China
| | - Zhiwen Wang
- Frontier Science Center for Synthetic BiologyTianjin UniversityTianjin300072P. R. China
- Key Laboratory of Systems Bioengineering (Ministry of Education)Tianjin UniversityTianjin300072P. R. China
- School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072P. R. China
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Li Y, Luo Q, Liu S, Su J, Chen J, Dong G, Wang Y. Transcriptome analysis of Shewanella xiamenensis co-incubated with internalized carbon dots in response to boosting Cr(VI)-bioreduction. Biochem Eng J 2023. [DOI: 10.1016/j.bej.2022.108775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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8
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Riboflavin-rich Agar Enhances the Rate of Extracellular Electron Transfer from Electrogenic Bacteria Inside a Thin-layer System. Bioelectrochemistry 2022; 148:108252. [DOI: 10.1016/j.bioelechem.2022.108252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/18/2022] [Accepted: 08/21/2022] [Indexed: 11/22/2022]
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Liu S, Liu H, Huang Y, Ma J, Wang Z, Chen R. Dielectric constants of organic pollutants determine their strength for enhancing microbial iron reduction. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:67445-67455. [PMID: 34254247 DOI: 10.1007/s11356-021-14060-9] [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: 12/17/2020] [Accepted: 04/19/2021] [Indexed: 06/13/2023]
Abstract
Physicochemical properties are essential characteristics of organic compounds, which not only impact the fate of organic pollutants but also determine their application in biological processes. Here, we first found that the dielectric constants (ɛ) of organic pollutants negatively correlated to their strength for enhancing microbial Fe(III) reduction. Those with lower ɛ values than 2.61 potentially promoted the above process following the sequence carbon tetrachloride (CT) > benzene > toluene > tetrachloroethylene (PCE) due to their different ability to deprotonate the phosphorus-related groups on the outer cell membrane of iron-reducing bacteria Shewanella oneidensis MR-1 (MR-1). The stronger deprotonation of phosphorus-related groups induced more negative charge of cell surface and more strongly increased cell membrane permeability and consequently stimulated faster release of flavin mononucleotide (FMN) as an electron shuttle/cofactor for Fe(III) reduction. These findings are significant for understanding the biogeochemistry in multi-organic contaminated subsurface and providing knowledge for remediation strategies and current production.
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Affiliation(s)
- Shan Liu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, People's Republic of China
- School of Environmental Studies, China University of Geosciences, Wuhan, 430078, People's Republic of China
| | - Hui Liu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, People's Republic of China.
- School of Environmental Studies, China University of Geosciences, Wuhan, 430078, People's Republic of China.
| | - Yao Huang
- School of Environmental Studies, China University of Geosciences, Wuhan, 430078, People's Republic of China
| | - Jie Ma
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, People's Republic of China
- School of Environmental Studies, China University of Geosciences, Wuhan, 430078, People's Republic of China
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, People's Republic of China
| | - Zhu Wang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, People's Republic of China
- School of Environmental Studies, China University of Geosciences, Wuhan, 430078, People's Republic of China
| | - Rong Chen
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, People's Republic of China
- School of Environmental Studies, China University of Geosciences, Wuhan, 430078, People's Republic of China
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Long X, Okamoto A. Outer membrane compositions enhance the rate of extracellular electron transport via cell-surface MtrC protein in Shewanella oneidensis MR-1. BIORESOURCE TECHNOLOGY 2021; 320:124290. [PMID: 33129092 DOI: 10.1016/j.biortech.2020.124290] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/13/2020] [Accepted: 10/15/2020] [Indexed: 06/11/2023]
Abstract
While cell membrane composition is critical for the function of membrane proteins, membrane modification has not been used to control the rate of extracellular electron transfer (EET) via the outer membrane protein complexes. Here, the rate of electron flow via the cell-surface redox protein, MtrC, was highly enhanced upon change in the outer membrane composition in Shewanella oneidensis MR-1. The MR-1 strain was pre-cultured at 4 °C and 30 °C to initiate differentiation of membrane composition. The whole-cell difference electrochemical assay of wild-type and mutant strains lacking MtrC suggested that the rate of EET via MtrC increased approximately 18 times at 4 °C than 30 °C. Circular dichroism spectroscopy showed that the molar exciton coupling coefficient for inter-heme interaction in MtrC increased in MR-1 at 4 °C than 30 °C. Results suggest that membrane modification may be a novel strategy for improving the efficiency of EET-based technologies.
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Affiliation(s)
- Xizi Long
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; School of Energy and Environment, Southeast University, Nanjing 210096, China
| | - Akihiro Okamoto
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 13 West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
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Zhao J, Li F, Cao Y, Zhang X, Chen T, Song H, Wang Z. Microbial extracellular electron transfer and strategies for engineering electroactive microorganisms. Biotechnol Adv 2020; 53:107682. [PMID: 33326817 DOI: 10.1016/j.biotechadv.2020.107682] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 11/04/2020] [Accepted: 12/09/2020] [Indexed: 11/27/2022]
Abstract
Electroactive microorganisms (EAMs) are ubiquitous in nature and have attracted considerable attention as they can be used for energy recovery and environmental remediation via their extracellular electron transfer (EET) capabilities. Although the EET mechanisms of Shewanella and Geobacter have been rigorously investigated and are well characterized, much less is known about the EET mechanisms of other microorganisms. For EAMs, efficient EET is crucial for the sustainable economic development of bioelectrochemical systems (BESs). Currently, the low efficiency of EET remains a key factor in limiting the development of BESs. In this review, we focus on the EET mechanisms of different microorganisms, (i.e., bacteria, fungi, and archaea). In addition, we describe in detail three engineering strategies for improving the EET ability of EAMs: (1) enhancing transmembrane electron transport via cytochrome protein channels; (2) accelerating electron transport via electron shuttle synthesis and transmission; and (3) promoting the microbe-electrode interface reaction via regulating biofilm formation. At the end of this review, we look to the future, with an emphasis on the cross-disciplinary integration of systems biology and synthetic biology to build high-performance EAM systems.
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Affiliation(s)
- Juntao Zhao
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), SynBioResearch Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China
| | - Feng Li
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), SynBioResearch Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China
| | - Yingxiu Cao
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), SynBioResearch Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China
| | - Xinbo Zhang
- Joint Research Centre for Protective Infrastructure Technology and Environmental Green Bioprocess, Department of Environmental and Municipal Engineering, Tianjin Chengjian University, Tianjin 300384, People's Republic of China
| | - Tao Chen
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), SynBioResearch Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China
| | - Hao Song
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), SynBioResearch Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China
| | - Zhiwen Wang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), SynBioResearch Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China.
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12
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Saito J, Deng X, Okamoto A. Single-Cell Mass Spectroscopic Analysis for Quantifying Active Metabolic Pathway Heterogeneity in a Bacterial Population on an Electrode. Anal Chem 2020; 92:15616-15623. [PMID: 33205944 DOI: 10.1021/acs.analchem.0c03869] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Microbial electrochemical catalysis based on respiratory reactions coupled with extracellular electron transport (EET), which is critical for bioenergy applications, strongly depends on the biocompatibility of the electrode material. However, the comparison of materials for such physiological responses has been difficult because of the lack of a quantitative assay for characterizing cellular metabolism at the electrode surface. Here, we developed a single-cell analysis method specific for the cells attached to the electrode to quantify active metabolic pathway heterogeneity as an index of physiological cell/electrode interaction, which generally increases with metabolic robustness in the microbial population. Nanoscale secondary ion mass spectrometry followed by microbial current production with model EET-capable bacteria, Shewanella oneidensis MR-1 and its mutant strains lacking carbon assimilation pathways, showed that different active metabolic pathways resulted in nearly identical 13C/15N assimilation ratios for individual cells in the presence of isotopically labeled nutrients, demonstrating a correlation between the 13C/15N ratio and the active metabolic pathway. Compared to the nonelectrode conditions, the heterogeneity of the assimilated 13C/15N ratio was highly enhanced on the electrode surface, suggesting that the metabolic robustness of the microbial population increased through the electrochemical interaction with the electrode. The present methodology enables us to quantitatively compare and screen electrode materials that increase the robustness of microbial electrocatalysis.
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Affiliation(s)
- Junki Saito
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.,International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Xiao Deng
- Land and Water, Commonwealth Scientific and Industrial Research Organization, 147 Underwood Avenue, Floreat, Western Australia 6014, Australia
| | - Akihiro Okamoto
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.,Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 13 West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
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Guo Y, Wang G, Zhang H, Wen H, Li W. Effects of biofilm transfer and electron mediators transfer on Klebsiella quasipneumoniae sp. 203 electricity generation performance in MFCs. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:162. [PMID: 32973923 PMCID: PMC7507662 DOI: 10.1186/s13068-020-01800-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 09/07/2020] [Indexed: 05/30/2023]
Abstract
BACKGROUND Extracellular electron transfer (EET) is essential in improving the power generation performance of electrochemically active bacteria (EAB) in microbial fuel cells (MFCs). Currently, the EET mechanisms of dissimilatory metal-reducing (DMR) model bacteria Shewanella oneidensis and Geobacter sulfurreducens have been thoroughly studied. Klebsiella has also been proved to be an EAB capable of EET, but the EET mechanism has not been perfected. This study investigated the effects of biofilm transfer and electron mediators transfer on Klebsiella quasipneumoniae sp. 203 electricity generation performance in MFCs. RESULTS Herein, we covered the anode of MFC with a layer of microfiltration membrane to block the effect of the biofilm mechanism, and then explore the EET of the electron mediator mechanism of K. quasipneumoniae sp. 203 and electricity generation performance. In the absence of short-range electron transfer, we found that K. quasipneumoniae sp. 203 can still produce a certain power generation performance, and coated-MFC reached 40.26 mW/m2 at a current density of 770.9 mA/m2, whereas the uncoated-MFC reached 90.69 mW/m2 at a current density of 1224.49 mA/m2. The difference in the electricity generation performance between coated-MFC and uncoated-MFC was probably due to the microfiltration membrane covered in anode, which inhibited the growth of EAB on the anode. Therefore, we speculated that K. quasipneumoniae sp. 203 can also perform EET through the biofilm mechanism. The protein content, the integrity of biofilm and the biofilm activity all proved that the difference in the electricity generation performance between coated-MFC and uncoated-MFC was due to the extremely little biomass of the anode biofilm. To further verify the effect of electron mediators on electricity generation performance of MFCs, 10 µM 2,6-DTBBQ, 2,6-DTBHQ and DHNA were added to coated-MFC and uncoated-MFC. Combining the time-voltage curve and CV curve, we found that 2,6-DTBBQ and 2,6-DTBHQ had high electrocatalytic activity toward the redox reaction of K. quasipneumoniae sp. 203-inoculated MFCs. It was also speculated that K. quasipneumoniae sp. 203 produced 2,6-DTBHQ and 2,6-DTBBQ. CONCLUSIONS To the best of our knowledge, the three modes of EET did not exist separately. K. quasipneumoniae sp.203 will adopt the corresponding electron transfer mode or multiple ways to realize EET according to the living environment to improve electricity generation performance.
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Affiliation(s)
- Yating Guo
- School of Life Sciences, Jiangsu Normal University, 101 Shanghai Road, Xuzhou, 221116 Jiangsu China
| | - Guozhen Wang
- School of Life Sciences, Jiangsu Normal University, 101 Shanghai Road, Xuzhou, 221116 Jiangsu China
| | - Hao Zhang
- School of Life Sciences, Jiangsu Normal University, 101 Shanghai Road, Xuzhou, 221116 Jiangsu China
| | - Hongyu Wen
- School of Life Sciences, Jiangsu Normal University, 101 Shanghai Road, Xuzhou, 221116 Jiangsu China
| | - Wen Li
- School of Life Sciences, Jiangsu Normal University, 101 Shanghai Road, Xuzhou, 221116 Jiangsu China
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14
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Li Y, Chen Z, Shi Y, Luo Q, Wang Y, Wang H, Peng Y, Wang H, He N, Wang Y. Function of c-type cytochromes of Shewanella xiamenensis in enhanced anaerobic bioreduction of Cr(VI) by graphene oxide and graphene oxide/polyvinyl alcohol films. JOURNAL OF HAZARDOUS MATERIALS 2020; 387:122018. [PMID: 31927260 DOI: 10.1016/j.jhazmat.2020.122018] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/29/2019] [Accepted: 01/02/2020] [Indexed: 06/10/2023]
Abstract
Graphene-based materials have been demonstrated to facilitate electron extracellular transfer (EET) of Shewanella. In this study, compared to group lacking graphene oxide (GO)-based materials, GO films-added group and graphene oxide/polyvinyl alcohol (GO/PVA) film-added group delivered 2.67- and 3.13-fold increases in the Cr(VI) reduction by Shewanella xiamenensis, respectively. The whole reduction process could be divided into three stages, including microbial Cr(VI) reduction and GO reduction stage, microbial GO reduction stage and microbial Cr(VI) reduction mediated by reduced graphene oxide (rGO) stage. Moreover, gene analysis revealed that addition of GO and GO/PVA films stimulated overexpression of several c-type cytochrome (c-Cyts) genes, including mtrA, mtrB, mtrC, mtrD, mtrE, mtrF, omcA, petC and SO-4047. Specifically, appreciable Cr(VI) reduction by the strains that overexpressed mtrA, mtrB, mtrC, mtrD, mtrE, mtrF and omcA further confirmed that overexpression of c-Cyts genes indeed enhanced the efficiency of Cr(VI) reduction. Based on these results, the specific function of every c-Cyt was clearly found in Cr(VI) reduction by the induction of GO-based materials. Our finding has disclosed a synergetic mechanism stimulated by GO-based materials to enhance Cr(VI) bioreduction that was not only mediated through the modification of material but also upregulated the expression of functional genes.
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Affiliation(s)
- Yixin Li
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, PR China
| | - Zheng Chen
- School of Environmental Science and Engineering, Tan Kah Kee College, Xiamen University, Zhangzhou, PR China; Zhejiang Provincial Key Laboratory of Watershed Science and Health, School of Public Health and Management, Wenzhou Medical University, Wenzhou, PR China; Fujian Provincial Key Lab of Coastal Basin Environment, Fujian Polytechnic Normal University, Fuqing, PR China.
| | - Yanyan Shi
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, PR China
| | - Qingliu Luo
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, PR China
| | - Yiming Wang
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, PR China
| | - Honghui Wang
- School of Environmental Science and Engineering, Tan Kah Kee College, Xiamen University, Zhangzhou, PR China
| | - Yajuan Peng
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, PR China
| | - Haitao Wang
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, PR China
| | - Ning He
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, PR China
| | - Yuanpeng Wang
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, PR China.
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15
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Liu W, Wu Y, Liu T, Li F, Dong H, Jing M. Influence of Incubation Temperature on 9,10-Anthraquinone-2-Sulfonate (AQS)-Mediated Extracellular Electron Transfer. Front Microbiol 2019; 10:464. [PMID: 30894849 PMCID: PMC6414795 DOI: 10.3389/fmicb.2019.00464] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 02/21/2019] [Indexed: 11/13/2022] Open
Abstract
The electron shuttling process has been recognized as an important microbial respiration process. Because the incubation temperature can influence both the reactivity of electron mediators and cell growth, it may also affect the electron-shuttle-mediated extracellular electron transfer (EET) process. Here, the effect of incubation temperature (22-38°C) was investigated in a bioelectrochemical system (BES) using Shewanella oneidensis MR-1 and 50 μM of 9,10-anthraquinone-2-sulfonate (AQS). We found that current generation increased as the temperature was increased from 22 to 34°C and then decreased sharply at 38°C. The biofilm biomass, as indicated by the total protein extracted from the electrode, increased as the temperature increased from 22 to 34°C and then decreased at 38°C, mirroring the current generation results. These results were further confirmed by increasing the temperature slowly, step-by-step, in a single BES with a constant biofilm biomass, suggesting that the EET rates could be substantially influenced by temperature, even with the same biofilm. The effects of temperature on the AQS bioreduction rate, c-type cytochrome (c-Cyts)-bound-cofactor-mediated EET, the AQS mid-point potential, and the AQS diffusion coefficient were studied. From these results, we were able to conclude that temperature influenced the EET rates by changing the c-Cyts-bound-cofactor-mediated EET process and the AQS bioreduction rate, and that the change in biofilm formation was a dominant factor influencing the overall EET rates. These findings should contribute to the fundamental understanding of EET processes. Moreover, optimization of the operating parameters for current generation will be helpful for the practical application of bioelectrochemical techniques.
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Affiliation(s)
- Wei Liu
- College of Materials and Energy, South China Agricultural University, Guangzhou, China
| | - Yundang Wu
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science and Technology, Guangzhou, China
| | - Tongxu Liu
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science and Technology, Guangzhou, China
| | - Fangbai Li
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science and Technology, Guangzhou, China
| | - Hui Dong
- College of Materials and Energy, South China Agricultural University, Guangzhou, China
| | - Meiqing Jing
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science and Technology, Guangzhou, China
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16
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Naradasu D, Miran W, Sakamoto M, Okamoto A. Isolation and Characterization of Human Gut Bacteria Capable of Extracellular Electron Transport by Electrochemical Techniques. Front Microbiol 2019; 9:3267. [PMID: 30697198 PMCID: PMC6340925 DOI: 10.3389/fmicb.2018.03267] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 12/17/2018] [Indexed: 01/09/2023] Open
Abstract
Microorganisms are known to exhibit extracellular electron transfer (EET) in a wide variety of habitats. However, as for the human microbiome which significantly impacts our health, the role and importance of EET has not been widely investigated. In this study, we enriched and isolated the EET-capable bacteria from human gut microbes using an electrochemical enrichment method and examined whether the isolates couple EET with anaerobic respiration or fermentation. Upon the use of energy-rich or minimum media (with acetate or lactate) for electrochemical enrichment with the human gut sample at an electrode potential of +0.4 V [vs. the standard hydrogen electrode (SHE)], both culture conditions showed significant current production. However, EET-capable pure strains were enriched specifically with minimum media, and subsequent incubation using the δ-MnO2-agar plate with lactate or acetate led to the isolation of two EET-capable microbial strains, Gut-S1 and Gut-S2, having 99% of 16S rRNA gene sequence identity with Enterococcus avium (E. avium) and Klebsiella pneumoniae (K. pneumoniae), respectively. While the enrichment involved anaerobic respiration with acetate and lactate, further electrochemistry with E. avium and K. pneumoniae revealed that the glucose fermentation was also coupled with EET. These results indicate that EET couples not only with anaerobic respiration as found in environmental bacteria, but also with fermentation in the human gut.
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Affiliation(s)
- Divya Naradasu
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, Tsukuba, Japan.,Department of Advanced Interdisciplinary Studies, Research Center for Advanced Science and Technology, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Waheed Miran
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, Tsukuba, Japan
| | - Mitsuo Sakamoto
- Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba, Japan.,PRIME, Japan Agency for Medical Research and Development (AMED), Tsukuba, Japan
| | - Akihiro Okamoto
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, Tsukuba, Japan.,PRIME, Japan Agency for Medical Research and Development (AMED), Tsukuba, Japan.,Center for Sensor and Actuator Material, National Institute for Materials Science (NIMS), Tsukuba, Japan
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17
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Murugan M, Miran W, Masuda T, Lee DS, Okamoto A. Biosynthesized Iron Sulfide Nanocluster Enhanced Anodic Current Generation by Sulfate Reducing Bacteria in Microbial Fuel Cells. ChemElectroChem 2018. [DOI: 10.1002/celc.201801086] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Muralidharan Murugan
- Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN)National Institute for Materials Science (NIMS) 1-1 Namiki, Tsukuba Ibaraki 305-0044 Japan
- Graduate School of Chemical Sciences and EngineeringHokkaido University Sapporo 060-8628 Japan
| | - Waheed Miran
- Department of Environmental EngineeringKyungpook National University 80 Daehak-ro, Buk-gu Daegu 41566 Republic of Korea
- International Center for Materials Nanoarchitectonics (WPI-MANA)National Institute for Materials Science (NIMS), Namiki, Tsukuba Ibaraki 305-0044 Japan
| | - Takuya Masuda
- Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN)National Institute for Materials Science (NIMS) 1-1 Namiki, Tsukuba Ibaraki 305-0044 Japan
| | - Dae S. Lee
- Department of Environmental EngineeringKyungpook National University 80 Daehak-ro, Buk-gu Daegu 41566 Republic of Korea
| | - Akihiro Okamoto
- International Center for Materials Nanoarchitectonics (WPI-MANA)National Institute for Materials Science (NIMS), Namiki, Tsukuba Ibaraki 305-0044 Japan
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18
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Okamoto A, Tokunou Y, Kalathil S, Hashimoto K. Proton Transport in the Outer‐Membrane Flavocytochrome Complex Limits the Rate of Extracellular Electron Transport. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201704241] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Akihiro Okamoto
- Global Research Center for Environment and Energy based on Nanomaterials Science National Institute for Material Science 1-1 Namiki, Tsukuba Ibaraki 305-0044 Japan
| | - Yoshihide Tokunou
- Department of Applied Chemistry The University of Tokyo 7-3-1 Hongo, Bunkyo-ku Tokyo 113-8656 Japan
| | - Shafeer Kalathil
- Department of Applied Chemistry The University of Tokyo 7-3-1 Hongo, Bunkyo-ku Tokyo 113-8656 Japan
| | - Kazuhito Hashimoto
- Global Research Center for Environment and Energy based on Nanomaterials Science National Institute for Material Science 1-1 Namiki, Tsukuba Ibaraki 305-0044 Japan
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19
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Okamoto A, Tokunou Y, Kalathil S, Hashimoto K. Proton Transport in the Outer-Membrane Flavocytochrome Complex Limits the Rate of Extracellular Electron Transport. Angew Chem Int Ed Engl 2017; 56:9082-9086. [PMID: 28608645 PMCID: PMC5575523 DOI: 10.1002/anie.201704241] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Indexed: 01/17/2023]
Abstract
The microbial transfer of electrons to extracellularly located solid compounds, termed extracellular electron transport (EET), is critical for microbial electrode catalysis. Although the components of the EET pathway in the outer membrane (OM) have been identified, the role of electron/cation coupling in EET kinetics is poorly understood. We studied the dynamics of proton transport associated with EET in an OM flavocytochrome complex in Shewanella oneidensis MR‐1. Using a whole‐cell electrochemical assay, a significant kinetic isotope effect (KIE) was observed following the addition of deuterated water (D2O). The removal of a flavin cofactor or key components of the OM flavocytochrome complex significantly increased the KIE in the presence of D2O to values that were significantly larger than those reported for proton channels and ATP synthase, thus indicating that proton transport by OM flavocytochrome complexes limits the rate of EET.
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Affiliation(s)
- Akihiro Okamoto
- Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Material Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Yoshihide Tokunou
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Shafeer Kalathil
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Kazuhito Hashimoto
- Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Material Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
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20
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Abstract
In MtrF, an outer-membrane multiheme cytochrome, the 10 heme groups are arranged in heme binding domains II and IV along the pseudo-C2 axis, forming the electron transfer (ET) pathways. Previous reports based on molecular dynamics simulations showed that the redox potential (Em) values for the heme pairs located in symmetrical positions in domains II and IV were similar, forming bidirectional ET pathways [Breuer M, Zarzycki P, Blumberger J, Rosso KM (2012) J Am Chem Soc 134(24):9868-9871]. Here, we present the Em values of the 10 hemes in MtrF, solving the linear Poisson-Boltzmann equation and considering the protonation states of all titratable residues and heme propionic groups. In contrast to previous studies, the Em values indicated that the ET is more likely to be downhill from domain IV to II because of localization of acidic residues in domain IV. Reduction of hemes in MtrF lowered the Em values, resulting in switching to alternative downhill ET pathways that extended to the flavin binding sites. These findings present an explanation of how MtrF serves as an electron donor to extracellular substrates.
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21
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SAITO J, HASHIMOTO K, OKAMOTO A. Nanoscale Secondary Ion Mass Spectrometry Analysis of Individual Bacterial Cells Reveals Feedback from Extracellular Electron Transport to Upstream Reactions. ELECTROCHEMISTRY 2017. [DOI: 10.5796/electrochemistry.85.444] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Junki SAITO
- Department of Applied Chemistry, School of Engineering, The University of Tokyo
| | - Kazuhito HASHIMOTO
- Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Materials Science
| | - Akihiro OKAMOTO
- Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Materials Science
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