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Gonzalez V, Abarca-Hurtado J, Arancibia A, Claverías F, Guevara MR, Orellana R. Novel Insights on Extracellular Electron Transfer Networks in the Desulfovibrionaceae Family: Unveiling the Potential Significance of Horizontal Gene Transfer. Microorganisms 2024; 12:1796. [PMID: 39338472 PMCID: PMC11434368 DOI: 10.3390/microorganisms12091796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2024] [Revised: 07/24/2024] [Accepted: 07/25/2024] [Indexed: 09/30/2024] Open
Abstract
Some sulfate-reducing bacteria (SRB), mainly belonging to the Desulfovibrionaceae family, have evolved the capability to conserve energy through microbial extracellular electron transfer (EET), suggesting that this process may be more widespread than previously believed. While previous evidence has shown that mobile genetic elements drive the plasticity and evolution of SRB and iron-reducing bacteria (FeRB), few have investigated the shared molecular mechanisms related to EET. To address this, we analyzed the prevalence and abundance of EET elements and how they contributed to their differentiation among 42 members of the Desulfovibrionaceae family and 23 and 59 members of Geobacteraceae and Shewanellaceae, respectively. Proteins involved in EET, such as the cytochromes PpcA and CymA, the outer membrane protein OmpJ, and the iron-sulfur cluster-binding CbcT, exhibited widespread distribution within Desulfovibrionaceae. Some of these showed modular diversification. Additional evidence revealed that horizontal gene transfer was involved in the acquiring and losing of critical genes, increasing the diversification and plasticity between the three families. The results suggest that specific EET genes were widely disseminated through horizontal transfer, where some changes reflected environmental adaptations. These findings enhance our comprehension of the evolution and distribution of proteins involved in EET processes, shedding light on their role in iron and sulfur biogeochemical cycling.
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Affiliation(s)
- Valentina Gonzalez
- Laboratorio de Biología Celular y Ecofisiología Microbiana, Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Leopoldo Carvallo 270, Valparaíso 2360001, Chile; (V.G.); (J.A.-H.); (A.A.)
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología Daniel Alkalay-Lowitt, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso 2390123, Chile;
- Departamento de Química y Medio Ambiente, Sede Viña del Mar, Universidad Técnica Federico Santa María, Avenida Federico Santa María 6090, Viña del Mar 2520000, Chile
| | - Josefina Abarca-Hurtado
- Laboratorio de Biología Celular y Ecofisiología Microbiana, Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Leopoldo Carvallo 270, Valparaíso 2360001, Chile; (V.G.); (J.A.-H.); (A.A.)
| | - Alejandra Arancibia
- Laboratorio de Biología Celular y Ecofisiología Microbiana, Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Leopoldo Carvallo 270, Valparaíso 2360001, Chile; (V.G.); (J.A.-H.); (A.A.)
- HUB Ambiental UPLA, Universidad de Playa Ancha, Leopoldo Carvallo 207, Playa Ancha, Valparaíso 2340000, Chile
| | - Fernanda Claverías
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología Daniel Alkalay-Lowitt, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso 2390123, Chile;
| | - Miguel R. Guevara
- Laboratorio de Data Science, Facultad de Ingeniería, Universidad de Playa Ancha, Leopoldo Carvallo 270, Valparaíso 2340000, Chile;
| | - Roberto Orellana
- Laboratorio de Biología Celular y Ecofisiología Microbiana, Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Leopoldo Carvallo 270, Valparaíso 2360001, Chile; (V.G.); (J.A.-H.); (A.A.)
- HUB Ambiental UPLA, Universidad de Playa Ancha, Leopoldo Carvallo 207, Playa Ancha, Valparaíso 2340000, Chile
- Núcleo Milenio BioGEM, Valparaíso 2390123, Chile
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2
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Hsu D, Flynn JR, Schuler CJ, Santelli CM, Toner BM, Bond DR, Gralnick JA. Isolation and genomic analysis of " Metallumcola ferriviriculae" MK1, a Gram-positive, Fe(III)-reducing bacterium from the Soudan Underground Mine, an iron-rich Martian analog site. Appl Environ Microbiol 2024; 90:e0004424. [PMID: 39007603 PMCID: PMC11337815 DOI: 10.1128/aem.00044-24] [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: 01/10/2024] [Accepted: 06/18/2024] [Indexed: 07/16/2024] Open
Abstract
The Soudan Underground Mine State Park, found in the Vermilion Iron Range in northern Minnesota, provides access to a ~ 2.7 billion-year-old banded iron formation. Exploratory boreholes drilled between 1958 and 1962 on the 27th level (713 m underground) of the mine intersect calcium and iron-rich brines that have recently been subject to metagenomic analysis and microbial enrichments. Using concentrated brine samples pumped from a borehole depth of up to 55 m, a novel Gram-positive bacterium was enriched under anaerobic, acetate-oxidizing, and Fe(III) citrate-reducing conditions. The isolated bacterium, designated strain MK1, is non-motile, rod-shaped, spore-forming, anaerobic, and mesophilic, with a growth range between 24°C and 30°C. The complete circular MK1 genome was found to be 3,720,236 bp and encodes 25 putative multiheme cytochromes, including homologs to inner membrane cytochromes in the Gram-negative bacterium Geobacter sulfurreducens and cytoplasmic membrane and periplasmic cytochromes in the Gram-positive bacterium Thermincola potens. However, MK1 does not encode homologs of the peptidoglycan (CwcA) and cell surface-associated (OcwA) multiheme cytochromes proposed to be required by T. potens to perform extracellular electron transfer. The 16S rRNA gene sequence of MK1 indicates that its closest related isolate is Desulfitibacter alkalitolerans strain sk.kt5 (91% sequence identity), which places MK1 in a novel genus within the Desulfitibacteraceae family and Moorellales order. Within the Moorellales order, only Calderihabitans maritimus strain KKC1 has been reported to reduce Fe(III), and only D. alkalitolerans can also grow in temperatures below 40°C. Thus, MK1 represents a novel species within a novel genus, for which we propose the name "Metallumcola ferriviriculae" strain MK1, and provides a unique opportunity to study a cytochrome-rich, mesophilic, Gram-positive, spore-forming Fe(III)-reducing bacterium.IMPORTANCEThe Soudan Underground Mine State Park gives access to understudied regions of the deep terrestrial subsurface that potentially predate the Great Oxidation Event. Studying organisms that have been relatively unperturbed by surface conditions for as long as 2.7 billion years may give us a window into ancient life before oxygen dominated the planet. Additionally, studying microbes from anoxic and iron-rich environments can help us better understand the requirements of life in analogous environments, such as on Mars. The isolation and characterization of "Metallumcola ferriviriculae" strain MK1 give us insights into a novel genus and species that is distinct both from its closest related isolates and from iron reducers characterized to date. "M. ferriviriculae" strain MK1 may also act as a model organism to study how the processes of sporulation and germination are affected by insoluble extracellular acceptors, as well as the impact of spores in the deep terrestrial biosphere.
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Affiliation(s)
- David Hsu
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Jack R. Flynn
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Christopher J. Schuler
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
| | - Cara M. Santelli
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
| | - Brandy M. Toner
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
- Department of Soil, Water, and Climate, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Daniel R. Bond
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Jeffrey A. Gralnick
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
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3
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Hou L, Zheng B, Jiang Z, Hu Y, Shi L, Dong Y, Jiang Y. The dmsEFABGH operon encodes an essential and modular electron transfer pathway for extracellular iodate reduction by Shewanella oneidensis MR-1. Microbiol Spectr 2024; 12:e0051224. [PMID: 38916364 PMCID: PMC11302344 DOI: 10.1128/spectrum.00512-24] [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: 02/27/2024] [Accepted: 06/03/2024] [Indexed: 06/26/2024] Open
Abstract
Extracellular iodate reduction by Shewanella spp. contributes to iodide generation in the biogeochemical cycling of iodine. However, there is a disagreement on whether Shewanella spp. use different extracellular electron transfer pathways with dependence on electron donors in iodate reduction. In this study, a series of gene deletion mutants of Shewanella oneidensis MR-1 were created to investigate the roles of dmsEFABGH, mtrCAB, and so4357-so4362 operons in iodate reduction. The iodate-reducing activity of the mutants was tested with lactate, formate, and H2 as the sole electron donors, respectively. In the absence of single-dms gene, iodate reduction efficiency of the mutants was only 12.9%-84.0% with lactate at 24 hours, 22.1%-85.9% with formate at 20 hours, and 19.6%-57.7% with H2 at 42 hours in comparison to complete reduction by the wild type. Progressive inhibition of iodate reduction was observed when the dms homolog from the so4357-so4362 operon was deleted in the single-dms gene mutants. This result revealed complementation of dmsEFABGH by so4357-so4362 at the single-gene level, indicating modularity of the extracellular electron transfer pathway encoded by dmsEFABGH operon. Under the conditions of all electron donors, significant inhibition of iodate reduction and accumulation of H2O2 were detected for ΔmtrCAB. Collectively, these results demonstrated that the dmsEFABGH operon encodes an essential and modular iodate-reducing pathway without electron donor dependence in S. oneidensis MR-1. The mtrCAB operon was involved in H2O2 elimination with all electron donors. The findings in this study improved the understanding of molecular mechanisms underlying extracellular iodate reduction.IMPORTANCEIodine is an essential trace element for human and animals. Recent studies revealed the contribution of microbial extracellular reduction of iodate in biogeochemical cycling of iodine. Multiple reduced substances can be utilized by microorganisms as energy source for iodate reduction. However, varied electron transfer pathways were proposed for iodate reduction with different electron donors in the model strain Shewanella oneidensis MR-1. Here, through a series of gene deletion and iodate reduction experiments, we discovered that the dmsEFABGH operon was essential for iodate reduction with at least three electron donors, including lactate, formate, and H2. The so4357-so4362 operon was first demonstrated to be capable of complementing the function of dmsEFABGH at single-gene level.
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Affiliation(s)
- Lingyu Hou
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China
| | - Beiling Zheng
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China
| | - Zhou Jiang
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China
| | - Yidan Hu
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China
| | - Liang Shi
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, Hubei, China
| | - Yiran Dong
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, Hubei, China
| | - Yongguang Jiang
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China
- Hubei Key Laboratory of Wetland Evolution & Eco-Restoration, Wuhan, Hubei, China
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4
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Ferreira MR, Morgado L, Salgueiro CA. Periplasmic electron transfer network in Geobacter sulfurreducens revealed by biomolecular interaction studies. Protein Sci 2024; 33:e5082. [PMID: 38935664 PMCID: PMC11210610 DOI: 10.1002/pro.5082] [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: 01/21/2024] [Revised: 05/31/2024] [Accepted: 06/03/2024] [Indexed: 06/29/2024]
Abstract
Multiheme cytochromes located in different compartments are crucial for extracellular electron transfer in the bacterium Geobacter sulfurreducens to drive important environmental processes and biotechnological applications. Recent studies have unveiled that for particular sets of electron terminal acceptors, discrete respiratory pathways selectively recruit specific cytochromes from both the inner and outer membranes. However, such specificity was not observed for the abundant periplasmic cytochromes, namely the triheme cytochrome family PpcA-E. In this work, the distinctive NMR spectroscopic signatures of these proteins in different redox states were explored to monitor pairwise interactions and electron transfer reactions between each pair of cytochromes. The results showed that the five proteins interact transiently and can exchange electrons between each other revealing intra-promiscuity within the members of this family. This discovery is discussed in the light of the establishment of an effective electron transfer network by this pool of cytochromes. This network is advantageous to the bacteria as it enables the maintenance of the functional working potential redox range within the cells.
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Affiliation(s)
- Marisa R. Ferreira
- 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
| | - 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
| | - 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
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Portela PC, Shipps CC, Shen C, Srikanth V, Salgueiro CA, Malvankar NS. Widespread extracellular electron transfer pathways for charging microbial cytochrome OmcS nanowires via periplasmic cytochromes PpcABCDE. Nat Commun 2024; 15:2434. [PMID: 38509081 PMCID: PMC10954620 DOI: 10.1038/s41467-024-46192-0] [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: 08/04/2023] [Accepted: 02/19/2024] [Indexed: 03/22/2024] Open
Abstract
Extracellular electron transfer (EET) via microbial nanowires drives globally-important environmental processes and biotechnological applications for bioenergy, bioremediation, and bioelectronics. Due to highly-redundant and complex EET pathways, it is unclear how microbes wire electrons rapidly (>106 s-1) from the inner-membrane through outer-surface nanowires directly to an external environment despite a crowded periplasm and slow (<105 s-1) electron diffusion among periplasmic cytochromes. Here, we show that Geobacter sulfurreducens periplasmic cytochromes PpcABCDE inject electrons directly into OmcS nanowires by binding transiently with differing efficiencies, with the least-abundant cytochrome (PpcC) showing the highest efficiency. Remarkably, this defined nanowire-charging pathway is evolutionarily conserved in phylogenetically-diverse bacteria capable of EET. OmcS heme reduction potentials are within 200 mV of each other, with a midpoint 82 mV-higher than reported previously. This could explain efficient EET over micrometres at ultrafast (<200 fs) rates with negligible energy loss. Engineering this minimal nanowire-charging pathway may yield microbial chassis with improved performance.
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Affiliation(s)
- Pilar C Portela
- Microbial Sciences Institute, Yale University, West Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Catharine C Shipps
- Microbial Sciences Institute, Yale University, West Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Cong Shen
- Microbial Sciences Institute, Yale University, West Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Vishok Srikanth
- Microbial Sciences Institute, Yale University, West Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Carlos A Salgueiro
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal.
- UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal.
| | - Nikhil S Malvankar
- Microbial Sciences Institute, Yale University, West Haven, CT, USA.
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA.
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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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7
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Ford KC, TerAvest MA. The electron transport chain of Shewanella oneidensis MR-1 can operate bidirectionally to enable microbial electrosynthesis. Appl Environ Microbiol 2024; 90:e0138723. [PMID: 38117056 PMCID: PMC10807441 DOI: 10.1128/aem.01387-23] [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: 08/11/2023] [Accepted: 11/13/2023] [Indexed: 12/21/2023] Open
Abstract
Extracellular electron transfer is a process by which bacterial cells can exchange electrons with a redox-active material located outside of the cell. In Shewanella oneidensis, this process is natively used to facilitate respiration using extracellular electron acceptors such as Fe(III) or an anode. Previously, it was demonstrated that this process can be used to drive the microbial electrosynthesis (MES) of 2,3-butanediol (2,3-BDO) in S. oneidensis exogenously expressing butanediol dehydrogenase (BDH). Electrons taken into the cell from a cathode are used to generate NADH, which in turn is used to reduce acetoin to 2,3-BDO via BDH. However, generating NADH via electron uptake from a cathode is energetically unfavorable, so NADH dehydrogenases couple the reaction to proton motive force. We therefore need to maintain the proton gradient across the membrane to sustain NADH production. This work explores accomplishing this task by bidirectional electron transfer, where electrons provided by the cathode go to both NADH formation and oxygen (O2) reduction by oxidases. We show that oxidases use trace dissolved oxygen in a microaerobic bioelectrical chemical system (BES), and the translocation of protons across the membrane during O2 reduction supports 2,3-BDO generation. Interestingly, this process is inhibited by high levels of dissolved oxygen in this system. In an aerated BES, O2 molecules react with the strong reductant (cathode) to form reactive oxygen species, resulting in cell death.IMPORTANCEMicrobial electrosynthesis (MES) is increasingly employed for the generation of specialty chemicals, such as biofuels, bioplastics, and cancer therapeutics. For these systems to be viable for industrial scale-up, it is important to understand the energetic requirements of the bacteria to mitigate unnecessary costs. This work demonstrates sustained production of an industrially relevant chemical driven by a cathode. Additionally, it optimizes a previously published system by removing any requirement for phototrophic energy, thereby removing the additional cost of providing a light source. We also demonstrate the severe impact of oxygen intrusion into bioelectrochemical systems, offering insight to future researchers aiming to work in an anaerobic environment. These studies provide insight into both the thermodynamics of electrosynthesis and the importance of the bioelectrochemical systems' design.
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Affiliation(s)
- Kathryne C. Ford
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Michaela A. TerAvest
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
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8
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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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9
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Abstract
Extracellular electron transfer (EET) is the physiological process that enables the reduction or oxidation of molecules and minerals beyond the surface of a microbial cell. The first bacteria characterized with this capability were Shewanella and Geobacter, both reported to couple their growth to the reduction of iron or manganese oxide minerals located extracellularly. A key difference between EET and nearly every other respiratory activity on Earth is the need to transfer electrons beyond the cell membrane. The past decade has resolved how well-conserved strategies conduct electrons from the inner membrane to the outer surface. However, recent data suggest a much wider and less well understood collection of mechanisms enabling electron transfer to distant acceptors. This review reflects the current state of knowledge from Shewanella and Geobacter, specifically focusing on transfer across the outer membrane and beyond-an activity that enables reduction of highly variable minerals, electrodes, and even other organisms.
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Affiliation(s)
- J A Gralnick
- BioTechnology Institute and Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA; ,
| | - D R Bond
- BioTechnology Institute and Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA; ,
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10
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Klein EM, Knoll MT, Gescher J. Microbe-Anode Interactions: Comparing the impact of genetic and material engineering approaches to improve the performance of microbial electrochemical systems (MES). Microb Biotechnol 2023; 16:1179-1202. [PMID: 36808480 PMCID: PMC10221544 DOI: 10.1111/1751-7915.14236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/20/2023] Open
Abstract
Microbial electrochemical systems (MESs) are a highly versatile platform technology with a particular focus on power or energy production. Often, they are used in combination with substrate conversion (e.g., wastewater treatment) and production of value-added compounds via electrode-assisted fermentation. This rapidly evolving field has seen great improvements both technically and biologically, but this interdisciplinarity sometimes hampers overseeing strategies to increase process efficiency. In this review, we first briefly summarize the terminology of the technology and outline the biological background that is essential for understanding and thus improving MES technology. Thereafter, recent research on improvements at the biofilm-electrode interface will be summarized and discussed, distinguishing between biotic and abiotic approaches. The two approaches are then compared, and resulting future directions are discussed. This mini-review therefore provides basic knowledge of MES technology and the underlying microbiology in general and reviews recent improvements at the bacteria-electrode interface.
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Affiliation(s)
- Edina M. Klein
- Institute of Technical MicrobiologyUniversity of Technology HamburgHamburgGermany
| | - Melanie T. Knoll
- Institute of Technical MicrobiologyUniversity of Technology HamburgHamburgGermany
| | - Johannes Gescher
- Institute of Technical MicrobiologyUniversity of Technology HamburgHamburgGermany
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11
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Li J, Han H, Chang Y, Wang B. The material-microorganism interface in microbial hybrid electrocatalysis systems. NANOSCALE 2023; 15:6009-6024. [PMID: 36912348 DOI: 10.1039/d3nr00742a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
This review presents a comprehensive summary of the material-microorganism interface in microbial hybrid electrocatalysis systems. Microbial hybrid electrocatalysis has been developed to combine the advantages of inorganic electrocatalysis and microbial catalysis. However, electron transfer at the interfaces between microorganisms and materials is a very critical issue that affects the efficiency of the system. Therefore, this review focuses on the electron transfer at the material-microorganism interface and the strategies for building efficient microorganism and material interfaces. We begin with a brief introduction of the electron transfer mechanism in both the bioanode and biocathode of bioelectrochemical systems to understand the material-microorganism interface. Next, we summarise the strategies for constructing efficient material-microorganism interfaces including material design and modification and bacterial engineering. We also discuss emerging studies on the bio-inorganic hybrid electrocatalysis system. Understanding the interface between electrode/active materials and the microorganisms, especially the electron transfer processes, could help to drive the evolution of material-microorganism hybrid electrocatalysis systems towards maturity.
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Affiliation(s)
- Jiyao Li
- Department of Environmental Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), Beijing 100190, China.
| | - Hexing Han
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), Beijing 100190, China.
| | - Yanhong Chang
- Department of Environmental Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Bin Wang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), Beijing 100190, China.
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12
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Verma M, Singh V, Mishra V. Moving towards the enhancement of extracellular electron transfer in electrogens. World J Microbiol Biotechnol 2023; 39:130. [PMID: 36959310 DOI: 10.1007/s11274-023-03582-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/15/2023] [Indexed: 03/25/2023]
Abstract
Electrogens are very common in nature and becoming a contemporary theme for research as they can be exploited for extracellular electron transfer. Extracellular electron transfer is the key mechanism behind bioelectricity generation and bioremediation of pollutants via microbes. Extracellular electron transfer mechanisms for electrogens other than Shewanella and Geobacter are less explored. An efficient extracellular electron transfer system is crucial for the sustainable future of bioelectrochemical systems. At present, the poor extracellular electron transfer efficiency remains a decisive factor in limiting the development of efficient bioelectrochemical systems. In this review article, the EET mechanisms in different electrogens (bacteria and yeast) have been focused. Apart from the well-known electron transfer mechanisms of Shewanella oneidensis and Geobacter metallireducens, a brief introduction of the EET pathway in Rhodopseudomonas palustris TIE-1, Sideroxydans lithotrophicus ES-1, Thermincola potens JR, Lysinibacillus varians GY32, Carboxydothermus ferrireducens, Enterococcus faecalis and Saccharomyces cerevisiae have been included. In addition to this, the article discusses the several approaches to anode modification and genetic engineering that may be used in order to increase the rate of extracellular electron transfer. In the side lines, this review includes the engagement of the electrogens for different applications followed by the future perspective of efficient extracellular electron transfer.
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Affiliation(s)
- Manisha Verma
- School of Biochemical Engineering, IIT (BHU), 221005, Varanasi, India
| | - Vishal Singh
- School of Biochemical Engineering, IIT (BHU), 221005, Varanasi, India
| | - Vishal Mishra
- School of Biochemical Engineering, IIT (BHU), 221005, Varanasi, India.
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13
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Bird LJ, Leary DH, Hervey J, Compton J, Phillips D, Tender LM, Voigt CA, Glaven SM. Marine Biofilm Engineered to Produce Current in Response to Small Molecules. ACS Synth Biol 2023; 12:1007-1020. [PMID: 36926839 DOI: 10.1021/acssynbio.2c00417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Engineered electroactive bacteria have potential applications ranging from sensing to biosynthesis. In order to advance the use of engineered electroactive bacteria, it is important to demonstrate functional expression of electron transfer modules in chassis adapted to operationally relevant conditions, such as non-freshwater environments. Here, we use the Shewanella oneidensis electron transfer pathway to induce current production in a marine bacterium, Marinobacter atlanticus, during biofilm growth in artificial seawater. Genetically encoded sensors optimized for use in Escherichia coli were used to control protein expression in planktonic and biofilm attached cells. Significant current production required the addition of menaquinone, which M. atlanticus does not produce, for electron transfer from the inner membrane to the expressed electron transfer pathway. Current through the S. oneidensis pathway in M. atlanticus was observed when inducing molecules were present during biofilm formation. Electron transfer was also reversible, indicating that electron transfer into M. atlanticus could be controlled. These results show that an operationally relevant marine bacterium can be genetically engineered for environmental sensing and response using an electrical signal.
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Affiliation(s)
- Lina J Bird
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Dagmar H Leary
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Judson Hervey
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Jaimee Compton
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Daniel Phillips
- Biochemistry Branch, Oak Ridge Institute for Science and Education/US Army DEVCOM Chemical Biological Center, Aberdeen Proving Grounds, Maryland 21005, United States
| | - Leonard M Tender
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Christopher A Voigt
- Department of Biological Engineering and the Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Sarah M Glaven
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
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14
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Atkinson JT, Chavez MS, Niman CM, El-Naggar MY. Living electronics: A catalogue of engineered living electronic components. Microb Biotechnol 2023; 16:507-533. [PMID: 36519191 PMCID: PMC9948233 DOI: 10.1111/1751-7915.14171] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 09/26/2022] [Accepted: 11/01/2022] [Indexed: 12/23/2022] Open
Abstract
Biology leverages a range of electrical phenomena to extract and store energy, control molecular reactions and enable multicellular communication. Microbes, in particular, have evolved genetically encoded machinery enabling them to utilize the abundant redox-active molecules and minerals available on Earth, which in turn drive global-scale biogeochemical cycles. Recently, the microbial machinery enabling these redox reactions have been leveraged for interfacing cells and biomolecules with electrical circuits for biotechnological applications. Synthetic biology is allowing for the use of these machinery as components of engineered living materials with tuneable electrical properties. Herein, we review the state of such living electronic components including wires, capacitors, transistors, diodes, optoelectronic components, spin filters, sensors, logic processors, bioactuators, information storage media and methods for assembling these components into living electronic circuits.
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Affiliation(s)
- Joshua T Atkinson
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, USA
| | - Marko S Chavez
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, USA
| | - Christina M Niman
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, USA
| | - Mohamed Y El-Naggar
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, USA.,Department of Biological Sciences, University of Southern California, Los Angeles, California, USA.,Department of Chemistry, University of Southern California, Los Angeles, California, USA
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15
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Wu Y, Zhu X, Wang X, Lin Z, Reinfelder JR, Li F, Liu T. A New Electron Shuttling Pathway Mediated by Lipophilic Phenoxazine via the Interaction with Periplasmic and Inner Membrane Proteins of Shewanella oneidensis MR-1. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:2636-2646. [PMID: 36652548 DOI: 10.1021/acs.est.2c07862] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Although it has been established that electron mediators substantially promote extracellular electron transfer (EET), electron shuttling pathways are not fully understood. Here, a new electron shuttling pathway was found in the EET process by Shewanella oneidensis MR-1 with resazurin, a lipophilic electron mediator. With resazurin, the genes encoding outer-membrane cytochromes (mtrCBA and omcA) were downregulated. Although cytochrome deletion substantially reduced biocurrent generation to 1-12% of that of wild-type (WT) cells, the presence of resazurin restored biocurrent generation to 168 μA·cm-2 (ΔmtrA/omcA/mtrC), nearly equivalent to that of WT cells (194 μA·cm-2), indicating that resazurin-mediated electron transfer was not dependent on the Mtr pathway. Biocurrent generation by resazurin was much lower in ΔcymA and ΔmtrA/omcA/mtrC/fccA/cctA mutants (4 and 6 μA·cm-2) than in WT cells, indicating a key role of FccA, CctA, and CymA in this process. The effectiveness of resazurin in EET of Mtr cytochrome mutants is also supported by cyclic voltammetry, resazurin reduction kinetics, and in situ c-type cytochrome spectroscopy results. The findings demonstrated that low molecular weight, lipophilic electron acceptors, such as phenoxazine and phenazine, may facilitate electron transfer directly from periplasmic and inner membrane proteins, thus providing new insight into the roles of exogenous electron mediators in electron shuttling in natural and engineered biogeochemical systems.
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Affiliation(s)
- Yundang Wu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Xiao Zhu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Xinxin Wang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- College of Materials and Energy, South China Agricultural University, Guangzhou 510642, China
| | - Zhixin Lin
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - John R Reinfelder
- Department of Environmental Sciences, Rutgers University, New Brunswick, New Jersey 08901, United States
| | - Fangbai Li
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Tongxu Liu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
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16
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The Extracellular Electron Transport Pathway Reduces Copper for Sensing by the CopRS Two-Component System under Anaerobic Conditions in Listeria monocytogenes. J Bacteriol 2023; 205:e0039122. [PMID: 36622231 PMCID: PMC9879103 DOI: 10.1128/jb.00391-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The renowned antimicrobial activity of copper stems in part from its ability to undergo redox cycling between Cu1+/2+ oxidation states. Bacteria counter copper toxicity with a network of sensors that often include two-component signaling systems to direct transcriptional responses. As in typical two-component systems, ligand binding by the extracellular domain of the membrane bound copper sensor component leads to phosphorylation and activation of the cognate response regulator transcription factor. In Listeria monocytogenes, the plasmid-borne CopRS two-component system upregulates both copper resistance and lipoprotein remodeling genes upon copper challenge, but the oxidation state of copper bound by CopS is unknown. Herein, we show CopS utilizes a triad of key residues (His-His-Phe) that are predicted to be at the dimerization interface and that are analogous with the Escherichia coli CusS copper sensor to specifically bind Cu1+/Ag1+ and activate CopR transcription. We demonstrate Cu2+ only induces CopRS if first reduced by electron transport systems, as strains lacking menaquinone carriers were unable to respond to Cu2+. The flavin-dependent extracellular electron transport system (EET) was the main mechanism for metal reduction, capable of either generating inducing ligand (Cu2+ to Cu1+) or removing it by precipitation (Ag1+ to Ag0). We show that EET flux is directly proportional to the rate of Cu2+ reduction and that since EET activity is low under oxygenated conditions when a competing respiratory chain is operating, CopRS signaling in turn is activated only under anaerobic conditions. EET metal reduction thus sensitizes cells to copper while providing resistance to silver under anaerobic growth. IMPORTANCE Two-component extracellular copper sensing from the periplasm of Gram-negative bacteria has been well studied, but copper detection at the cell surface of the Gram-positive L. monocytogenes is less understood. Collectively, our results show that EET is most active under anaerobic conditions and reduces Cu2+ and Ag1+ to, respectively, generate or remove the monovalent ligands that directly bind to CopS and lead to the induction of lipoprotein remodeling genes. This reducing activity regulates CopRS signaling and links the upregulation of copper resistance genes with increasing EET flux. Our studies provide insight into how a two-component copper sensing system is integrated into a model monoderm Firmicute to take cues from the electron transport chain activity.
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17
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Tang Z, Liu R, Chen X, Gao D, Zhang JR, Zhu JJ, Chen Z. Plasmonic Probing Single-Cell Bio-Current Waves with a Shrinking Magnetite Nanoprobe. ACS NANO 2022; 16:20842-20850. [PMID: 36475619 DOI: 10.1021/acsnano.2c08223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Probing of the single-cell level extracellular electron transfer highlights the maximum output current for microbial fuel cells (MFCs) at hundreds of femtoampere per cell, which is difficult to achieve by existing devices. Past studies focus on the external factors for boosting charge-extraction efficiency from bacteria. Here, we elucidate the intracellular factors that determine this output limit by monitoring the respiratory-driven shrinking kinetics of a single magnetite nanoprobe immobilized on a single Shewanella oneidensis MR-1 cell with plasmonic imaging. Quantified dissolving of nanoprobes unveils a previously undescribed bio-current fluctuation between 0 and 2.7 fA on a ∼40 min cycle. Simultaneously tracing of endogenous oscillations indicates that the bio-current waves are correlated with the periodic cellular electrokinesis. The unsynchronized electron transfer capability in the cell population results in the mean current of 0.24 fA per cell, significantly smaller than in single cells. It explains why the averaged output current of MFCs cannot reach the measured single-cell currents. This work offers a different perspective to improve the power output by extending the active episodes of the bio-current waves.
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Affiliation(s)
- Zhuodong Tang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing210023, People's Republic of China
| | - Rui Liu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing210023, People's Republic of China
| | - Xueqin Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing210023, People's Republic of China
| | - Di Gao
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing210023, People's Republic of China
| | - Jian-Rong Zhang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing210023, People's Republic of China
| | - Jun-Jie Zhu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing210023, People's Republic of China
- Shenzhen Research Institute of Nanjing University, Shenzhen518000, People's Republic of China
| | - Zixuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing210023, People's Republic of China
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18
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Choi S, Chan CH, Bond DR. Lack of Specificity in Geobacter Periplasmic Electron Transfer. J Bacteriol 2022; 204:e0032222. [PMID: 36383007 PMCID: PMC9765071 DOI: 10.1128/jb.00322-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 10/23/2022] [Indexed: 11/17/2022] Open
Abstract
Reduction of extracellular acceptors requires electron transfer across the periplasm. In Geobacter sulfurreducens, three separate cytoplasmic membrane cytochromes are utilized depending on redox potential, and at least five cytochrome conduits span the outer membrane. Because G. sulfurreducens produces 5 structurally similar triheme periplasmic cytochromes (PpcABCDE) that differ in expression level, midpoint potential, and heme biochemistry, many hypotheses propose distinct periplasmic carriers could be used for specific redox potentials, terminal acceptors, or growth conditions. Using a panel of marker-free single, quadruple, and quintuple mutants, little support for these models could be found. Three quadruple mutants containing only one paralog (PpcA, PpcB, and PpcD) reduced Fe(III) citrate and Fe(III) oxide at the same rate and extent, even though PpcB and PpcD were at much lower periplasmic levels than PpcA. Mutants containing only PpcC and PpcE showed defects, but these cytochromes were nearly undetectable in the periplasm. When expressed sufficiently, PpcC and PpcE supported wild-type Fe(III) reduction. PpcA and PpcE from G. metallireducens similarly restored metal respiration in G. sulfurreducens. PgcA, an unrelated extracellular triheme c-type cytochrome, also participated in periplasmic electron transfer. While triheme cytochromes were important for metal reduction, sextuple ΔppcABCDE ΔpgcA mutants grew near wild-type rates with normal cyclic voltammetry profiles when using anodes as electron acceptors. These results reveal broad promiscuity in the periplasmic electron transfer network of metal-reducing Geobacter and suggest that an as-yet-undiscovered periplasmic mechanism supports electron transfer to electrodes. IMPORTANCE Many inner and outer membrane cytochromes used by Geobacter for electron transfer to extracellular acceptors have specific functions. How these are connected by periplasmic carriers remains poorly understood. G. sulfurreducens contains multiple triheme periplasmic cytochromes with unique biochemical properties and expression profiles. It is hypothesized that each could be involved in a different respiratory pathway, depending on redox potential or energy needs. Here, we show that Geobacter periplasmic cytochromes instead show evidence of being highly promiscuous. Any of 6 triheme cytochromes supported similar growth with soluble or insoluble metals, but none were required when cells utilized electrodes. These findings fail to support many models of Geobacter electron transfer, and question why these organisms produce such an array of periplasmic cytochromes.
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Affiliation(s)
- Sol Choi
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Chi Ho Chan
- BioTechnology Institute, University of Minnesota, Saint Paul, Minnesota, USA
| | - Daniel R. Bond
- BioTechnology Institute, University of Minnesota, Saint Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, Minnesota, USA
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19
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Feng H, Xu L, Chen R, Ma X, Qiao H, Zhao N, Ding Y, Wu D. Detoxification mechanisms of electroactive microorganisms under toxicity stress: A review. Front Microbiol 2022; 13:1084530. [DOI: 10.3389/fmicb.2022.1084530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 11/14/2022] [Indexed: 11/30/2022] Open
Abstract
Remediation of environmental toxic pollutants has attracted extensive attention in recent years. Microbial bioremediation has been an important technology for removing toxic pollutants. However, microbial activity is also susceptible to toxicity stress in the process of intracellular detoxification, which significantly reduces microbial activity. Electroactive microorganisms (EAMs) can detoxify toxic pollutants extracellularly to a certain extent, which is related to their unique extracellular electron transfer (EET) function. In this review, the extracellular and intracellular aspects of the EAMs’ detoxification mechanisms are explored separately. Additionally, various strategies for enhancing the effect of extracellular detoxification are discussed. Finally, future research directions are proposed based on the bottlenecks encountered in the current studies. This review can contribute to the development of toxic pollutants remediation technologies based on EAMs, and provide theoretical and technical support for future practical engineering applications.
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20
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Jain A, Kalb MJ, Gralnick JA. Reconstructing electron transfer components from an Fe(II) oxidizing bacterium. Microbiology (Reading) 2022; 168. [DOI: 10.1099/mic.0.001240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neutrophilic Fe(II) oxidizing bacteria play an important role in biogeochemical processes and have also received attention for multiple technological applications. These micro-organisms are thought to couple their metabolism with extracellular electron transfer (EET) while oxidizing Fe(II) as electron donor outside the cell. Sideroxydans lithotrophicus ES-1 is a freshwater chemolithoautotrophic Fe(II) oxidizing bacterium that is challenging to culture and not yet genetically tractable. Analysis of the S. lithotrophicus ES-1 genome predicts multiple EET pathways, which are proposed to be involved in Fe(II) oxidation, but not yet validated. Here we expressed components of two of the proposed EET pathways, including the Mto and Slit_0867–0870 PCC3 pathways, from S. lithotrophicus ES-1 into
Aeromonas hydrophila
, an established model EET organism. We demonstrate that combinations of putative inner membrane and periplasmic components from the Mto and Slit_0867–0870 PCC3 pathways partially complemented EET activity in
Aeromonas
mutants lacking native components. Our results provide evidence for electron transfer functionality and interactions of inner membrane and periplasmic components from the Mto and Slit_0867–0870 PCC3 pathways. Based on these findings, we suggest that EET in S. lithotrophicus ES-1 could be more complicated than previously considered and raises questions regarding directionality of these electron transfer pathways.
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Affiliation(s)
- Abhiney Jain
- BioTechnology Institute and Department of Plant and Microbial Biology, University of Minnesota — Twin Cities, St. Paul, MN 55108, USA
| | - Madison J. Kalb
- BioTechnology Institute and Department of Plant and Microbial Biology, University of Minnesota — Twin Cities, St. Paul, MN 55108, USA
| | - Jeffrey A. Gralnick
- BioTechnology Institute and Department of Plant and Microbial Biology, University of Minnesota — Twin Cities, St. Paul, MN 55108, USA
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21
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Guo J, Jiang Y, Hu Y, Jiang Z, Dong Y, Shi L. The Roles of DmsEFAB and MtrCAB in Extracellular Reduction of Iodate by Shewanella oneidensis MR-1 with Lactate as the Sole Electron Donor. Environ Microbiol 2022; 24:5039-5050. [PMID: 35837844 DOI: 10.1111/1462-2920.16130] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 06/27/2022] [Accepted: 07/06/2022] [Indexed: 11/26/2022]
Abstract
To investigate their roles in extracellular reduction of iodate (IO3 - ) with lactate as an electron donor, the gene clusters of dmsEFAB, mtrCAB, mtrDEF, and so4360-4357 in Shewanella oneidensis MR-1were systematically deleted. Deletions of dmsEFAB and/or mtrCAB gene clusters diminished the bacterial ability to reduce IO3 - . Furthermore, DmsEFAB and MtrCAB worked collaboratively to reduce IO3 - of which DmsEFAB played a more dominant role than MtrCAB. MtrCAB was involved in detoxifying the reaction intermediate hydrogen peroxide (H2 O2 ). The reaction intermediate hypoiodous acid (HIO) was also found to inhibit microbial IO3 - reduction. SO4360-4357 and MtrDEF, however, were not involved in IO3 - reduction. Collectively, these results suggest a novel mechanism of extracellular reduction of IO3 - at molecular level, in which DmsEFAB reduces IO3 - to HIO and H2 O2 . The latter is further reduced to H2 O by MtrCAB to facilitate the DmsEFAB-mediated IO3 - reduction. The extracellular electron transfer pathway of S. oneidensis MR-1is believed to mediate electron transfer from bacterial cytoplasmic membrane, across the cell envelope to the DmsEFAB and MtrCAB on the bacterial outer membrane.
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Affiliation(s)
- Jinzhi Guo
- Department of Biological Sciences and Technology, School of Environmental Studies, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, Hubei, China
| | - Yongguang Jiang
- Department of Biological Sciences and Technology, School of Environmental Studies, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, Hubei, China
| | - Yidan Hu
- Department of Biological Sciences and Technology, School of Environmental Studies, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, Hubei, China
| | - Zhou Jiang
- Department of Biological Sciences and Technology, School of Environmental Studies, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, Hubei, China
| | - Yiran Dong
- Department of Biological Sciences and Technology, School of Environmental Studies, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, Hubei, China.,State Key Laboratory of Biogeology and Environmental Geology, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, Hubei, China.,Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, Hubei, China
| | - Liang Shi
- Department of Biological Sciences and Technology, School of Environmental Studies, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, Hubei, China.,State Key Laboratory of Biogeology and Environmental Geology, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, Hubei, China.,Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, Hubei, China.,State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, Ministry of Ecology and Environment, China University of Geosciences, Wuhan, Hubei, China
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22
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Membrane-anchored HDCR nanowires drive hydrogen-powered CO 2 fixation. Nature 2022; 607:823-830. [PMID: 35859174 DOI: 10.1038/s41586-022-04971-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 06/13/2022] [Indexed: 01/11/2023]
Abstract
Filamentous enzymes have been found in all domains of life, but the advantage of filamentation is often elusive1. Some anaerobic, autotrophic bacteria have an unusual filamentous enzyme for CO2 fixation-hydrogen-dependent CO2 reductase (HDCR)2,3-which directly converts H2 and CO2 into formic acid. HDCR reduces CO2 with a higher activity than any other known biological or chemical catalyst4,5, and it has therefore gained considerable interest in two areas of global relevance: hydrogen storage and combating climate change by capturing atmospheric CO2. However, the mechanistic basis of the high catalytic turnover rate of HDCR has remained unknown. Here we use cryo-electron microscopy to reveal the structure of a short HDCR filament from the acetogenic bacterium Thermoanaerobacter kivui. The minimum repeating unit is a hexamer that consists of a formate dehydrogenase (FdhF) and two hydrogenases (HydA2) bound around a central core of hydrogenase Fe-S subunits, one HycB3 and two HycB4. These small bacterial polyferredoxin-like proteins oligomerize through their C-terminal helices to form the backbone of the filament. By combining structure-directed mutagenesis with enzymatic analysis, we show that filamentation and rapid electron transfer through the filament enhance the activity of HDCR. To investigate the structure of HDCR in situ, we imaged T. kivui cells with cryo-electron tomography and found that HDCR filaments bundle into large ring-shaped superstructures attached to the plasma membrane. This supramolecular organization may further enhance the stability and connectivity of HDCR to form a specialized metabolic subcompartment within the cell.
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23
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Gao Z, Su J, Ali A, Wang X, Bai Y, Wang Y, Wang Z. Denitrification strategy of Pantoea sp. MFG10 coupled with microbial dissimilatory manganese reduction: Deciphering the physiological response based on extracellular secretion. BIORESOURCE TECHNOLOGY 2022; 355:127278. [PMID: 35545210 DOI: 10.1016/j.biortech.2022.127278] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
In this study, the manganese (Mn) reduction-coupled denitrification strategy of dissimilatory Mn reducing bacteria was insightfully investigated. Different parameters (MnO2 level, pH, and temperature) were optimized by kinetic fitting to improve denitrification and Mn reduction effects. The 300 mg L-1 MnO2 addition achieved 98.72% NO3--N removal in 12 h, which was 54.62% higher than blank group without MnO2. Scale-up studies showed that the metabolic activity of the bacteria was effectively enhanced by the addition of MnO2. Besides the deepening of humification in the system, tryptophan-like protein and polysaccharide as potential electron donor precursors revealed remarkable contributions to the extracellular secretion-dependent denitrification process of DMRB. The effect of EPS on Mn reduction depends mainly on the capture of MnO2 by the LB-EPS layer versus its dissolution in the TB-EPS layer. Ultimately, the EPS possess a dual effect of accelerated denitrification and Mn reduction efficiency due to the enhanced EET process.
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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
| | - 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
| | - Xumian 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
| | - 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
| | - 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
| | - Zhao 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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24
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Anand A, Patel A, Chen K, Olson CA, Phaneuf PV, Lamoureux C, Hefner Y, Szubin R, Feist AM, Palsson BO. Laboratory evolution of synthetic electron transport system variants reveals a larger metabolic respiratory system and its plasticity. Nat Commun 2022; 13:3682. [PMID: 35760776 PMCID: PMC9237125 DOI: 10.1038/s41467-022-30877-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 05/24/2022] [Indexed: 11/09/2022] Open
Abstract
The bacterial respiratory electron transport system (ETS) is branched to allow condition-specific modulation of energy metabolism. There is a detailed understanding of the structural and biochemical features of respiratory enzymes; however, a holistic examination of the system and its plasticity is lacking. Here we generate four strains of Escherichia coli harboring unbranched ETS that pump 1, 2, 3, or 4 proton(s) per electron and characterized them using a combination of synergistic methods (adaptive laboratory evolution, multi-omic analyses, and computation of proteome allocation). We report that: (a) all four ETS variants evolve to a similar optimized growth rate, and (b) the laboratory evolutions generate specific rewiring of major energy-generating pathways, coupled to the ETS, to optimize ATP production capability. We thus define an Aero-Type System (ATS), which is a generalization of the aerobic bioenergetics and is a metabolic systems biology description of respiration and its inherent plasticity. The bacterial respiratory electron transport system (ETS) is branched to allow condition-specific modulation of energy metabolism. Here the authors examine the systems level properties of aerobic electron transport system using adaptive laboratory evolution and multi-omics analyses.
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Affiliation(s)
- Amitesh Anand
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA. .,Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra, India.
| | - Arjun Patel
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Ke Chen
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Connor A Olson
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Patrick V Phaneuf
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Cameron Lamoureux
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Ying Hefner
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Richard Szubin
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Adam M Feist
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.,Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Kongens, Lyngby, Denmark
| | - Bernhard O Palsson
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA. .,Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Kongens, Lyngby, Denmark.
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25
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Chen Z, Zhang J, Lyu Q, Wang H, Ji X, Yan Z, Chen F, Dahlgren RA, Zhang M. Modular configurations of living biomaterials incorporating nano-based artificial mediators and synthetic biology to improve bioelectrocatalytic performance: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 824:153857. [PMID: 35176368 DOI: 10.1016/j.scitotenv.2022.153857] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/24/2022] [Accepted: 02/09/2022] [Indexed: 06/14/2023]
Abstract
Currently, the industrial application of bioelectrochemical systems (BESs) that are incubated with natural electrochemically active microbes (EABs) is limited due to inefficient extracellular electron transfer (EET) by natural EABs. Notably, recent studies have identified several novel living biomaterials comprising highly efficient electron transfer systems allowing unparalleled proficiency of energy conversion. Introduction of these biomaterials into BESs could fundamentally increase their utilization for a wide range of applications. This review provides a comprehensive assessment of recent advancements in the design of living biomaterials that can be exploited to enhance bioelectrocatalytic performance. Further, modular configurations of abiotic and biotic components promise a powerful enhancement through integration of nano-based artificial mediators and synthetic biology. Herein, recent advancements in BESs are synthesized and assessed, including heterojunctions between conductive nanomaterials and EABs, in-situ hybrid self-assembly of EABs and nano-sized semiconductors, cytoprotection in biohybrids, synthetic biological modifications of EABs and electroactive biofilms. Since living biomaterials comprise a broad range of disciplines, such as molecular biology, electrochemistry and material sciences, full integration of technological advances applied in an interdisciplinary framework will greatly enhance/advance the utility and novelty of BESs. Overall, emerging fundamental knowledge concerning living biomaterials provides a powerful opportunity to markedly boost EET efficiency and facilitate the industrial application of BESs to meet global sustainability challenges/goals.
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Affiliation(s)
- Zheng Chen
- School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, People's Republic of China; School of Environmental Science & Engineering, Tan Kah Kee College, Xiamen University, Zhangzhou 363105, People's Republic of China; Fujian Provincial Key Lab of Coastal Basin Environment, Fujian Polytechnic Normal University, Fuqing 350300, People's Republic of China.
| | - Jing Zhang
- School of Environmental Science & Engineering, Tan Kah Kee College, Xiamen University, Zhangzhou 363105, People's Republic of China
| | - Qingyang Lyu
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China
| | - Honghui Wang
- School of Environmental Science & Engineering, Tan Kah Kee College, Xiamen University, Zhangzhou 363105, People's Republic of China
| | - Xiaoliang Ji
- School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, People's Republic of China
| | - Zhiying Yan
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China
| | - Fang Chen
- Fujian Provincial Key Lab of Coastal Basin Environment, Fujian Polytechnic Normal University, Fuqing 350300, People's Republic of China
| | - Randy A Dahlgren
- School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, People's Republic of China; Department of Land, Air and Water Resources, University of California, Davis, CA 95616, USA
| | - Minghua Zhang
- School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, People's Republic of China; Department of Land, Air and Water Resources, University of California, Davis, CA 95616, USA
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26
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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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27
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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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28
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Bird LJ, Kundu BB, Tschirhart T, Corts AD, Su L, Gralnick JA, Ajo-Franklin CM, Glaven SM. Engineering Wired Life: Synthetic Biology for Electroactive Bacteria. ACS Synth Biol 2021; 10:2808-2823. [PMID: 34637280 DOI: 10.1021/acssynbio.1c00335] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Electroactive bacteria produce or consume electrical current by moving electrons to and from extracellular acceptors and donors. This specialized process, known as extracellular electron transfer, relies on pathways composed of redox active proteins and biomolecules and has enabled technologies ranging from harvesting energy on the sea floor, to chemical sensing, to carbon capture. Harnessing and controlling extracellular electron transfer pathways using bioengineering and synthetic biology promises to heighten the limits of established technologies and open doors to new possibilities. In this review, we provide an overview of recent advancements in genetic tools for manipulating native electroactive bacteria to control extracellular electron transfer. After reviewing electron transfer pathways in natively electroactive organisms, we examine lessons learned from the introduction of extracellular electron transfer pathways into Escherichia coli. We conclude by presenting challenges to future efforts and give examples of opportunities to bioengineer microbes for electrochemical applications.
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Affiliation(s)
- Lina J. Bird
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Biki B. Kundu
- PhD Program in Systems, Synthetic, and Physical Biology, Rice University, Houston, Texas 77005, United States
| | - Tanya Tschirhart
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Anna D. Corts
- Joyn Bio, Boston, Massachusetts 02210, United States
| | - Lin Su
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210018, People’s Republic of China
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Jeffrey A. Gralnick
- Department of Plant and Microbial Biology, BioTechnology Institute, University of Minnesota, St. Paul, Minnesota 55108, United States
| | | | - Sarah M. Glaven
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, D.C. 20375, United States
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29
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Baruch M, Tejedor-Sanz S, Su L, Ajo-Franklin CM. Electronic control of redox reactions inside Escherichia coli using a genetic module. PLoS One 2021; 16:e0258380. [PMID: 34793478 PMCID: PMC8601525 DOI: 10.1371/journal.pone.0258380] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 09/26/2021] [Indexed: 11/22/2022] Open
Abstract
Microorganisms regulate the redox state of different biomolecules to precisely control biological processes. These processes can be modulated by electrochemically coupling intracellular biomolecules to an external electrode, but current approaches afford only limited control and specificity. Here we describe specific electrochemical control of the reduction of intracellular biomolecules in Escherichia coli through introduction of a heterologous electron transfer pathway. E. coli expressing cymAmtrCAB from Shewanella oneidensis MR-1 consumed electrons directly from a cathode when fumarate or nitrate, both intracellular electron acceptors, were present. The fumarate-triggered current consumption occurred only when fumarate reductase was present, indicating all the electrons passed through this enzyme. Moreover, CymAMtrCAB-expressing E. coli used current to stoichiometrically reduce nitrate. Thus, our work introduces a modular genetic tool to reduce a specific intracellular redox molecule with an electrode, opening the possibility of electronically controlling biological processes such as biosynthesis and growth in any microorganism.
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Affiliation(s)
- Moshe Baruch
- The Molecular Foundry, Biological Nanostructures Facility, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Sara Tejedor-Sanz
- The Molecular Foundry, Biological Nanostructures Facility, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of BioSciences, Rice University, Houston, Texas, United States of America
| | - Lin Su
- The Molecular Foundry, Biological Nanostructures Facility, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of BioSciences, Rice University, Houston, Texas, United States of America
| | - Caroline M. Ajo-Franklin
- The Molecular Foundry, Biological Nanostructures Facility, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of BioSciences, Rice University, Houston, Texas, United States of America
- Institute for Biosciences and Bioengineering, Rice University, Houston, Texas, United States of America
- * E-mail:
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30
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Insights into the Biosynthesis of Nanoparticles by the Genus Shewanella. Appl Environ Microbiol 2021; 87:e0139021. [PMID: 34495739 DOI: 10.1128/aem.01390-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The exploitation of microorganisms for the fabrication of nanoparticles (NPs) has garnered considerable research interest globally. The microbiological transformation of metals and metal salts into respective NPs can be achieved under environmentally benign conditions, offering a more sustainable alternative to chemical synthesis methods. Species of the metal-reducing bacterial genus Shewanella are able to couple the oxidation of various electron donors, including lactate, pyruvate, and hydrogen, to the reduction of a wide range of metal species, resulting in biomineralization of a multitude of metal NPs. Single-metal-based NPs as well as composite materials with properties equivalent or even superior to physically and chemically produced NPs have been synthesized by a number of Shewanella species. A mechanistic understanding of electron transfer-mediated bioreduction of metals into respective NPs by Shewanella is crucial in maximizing NP yields and directing the synthesis to produce fine-tuned NPs with tailored properties. In addition, thorough investigations into the influence of process parameters controlling the biosynthesis is another focal point for optimizing the process of NP generation. Synthesis of metal-based NPs using Shewanella species offers a low-cost, eco-friendly alternative to current physiochemical methods. This article aims to shed light on the contribution of Shewanella as a model organism in the biosynthesis of a variety of NPs and critically reviews the current state of knowledge on factors controlling their synthesis, characterization, potential applications in different sectors, and future prospects.
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31
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Sun W, Lin Z, Yu Q, Cheng S, Gao H. Promoting Extracellular Electron Transfer of Shewanella oneidensis MR-1 by Optimizing the Periplasmic Cytochrome c Network. Front Microbiol 2021; 12:727709. [PMID: 34675900 PMCID: PMC8524038 DOI: 10.3389/fmicb.2021.727709] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 09/13/2021] [Indexed: 11/13/2022] Open
Abstract
The low efficiency of extracellular electron transfer (EET) is a major bottleneck for Shewanella oneidensis MR-1 acting as an electroactive biocatalyst in bioelectrochemical systems. Although it is well established that a periplasmic c-type cytochrome (c-Cyt) network plays a critical role in regulating EET efficiency, the understanding of the network in terms of structure and electron transfer activity is obscure and partial. In this work, we attempted to systematically investigate the impacts of the network components on EET in their absence and overproduction individually in microbial fuel cell (MFC). We found that overexpression of c-Cyt CctA leads to accelerated electron transfer between CymA and the Mtr system, which function as the primary quinol oxidase and the outer-membrane (OM) electron hub in EET. In contrast, NapB, FccA, and TsdB in excess severely impaired EET, reducing EET capacity in MFC by more than 50%. Based on the results from both strategies, a series of engineered strains lacking FccA, NapB, and TsdB in combination while overproducing CctA were tested for a maximally optimized c-Cyt network. A strain depleted of all NapB, FccA, and TsdB with CctA overproduction achieved the highest maximum power density in MFCs (436.5 mW/m2), ∼3.62-fold higher than that of wild type (WT). By revealing that optimization of periplasmic c-Cyt composition is a practical strategy for improving EET efficiency, our work underscores the importance in understanding physiological and electrochemical characteristics of c-Cyts involved in EET.
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Affiliation(s)
- Weining Sun
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Zhufan Lin
- Department of Energy Engineering, State Key Laboratory of Clean Energy, Zhejiang University, Hangzhou, China
| | - Qingzi Yu
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Shaoan Cheng
- Department of Energy Engineering, State Key Laboratory of Clean Energy, Zhejiang University, Hangzhou, China
| | - Haichun Gao
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, China
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32
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Piper SEH, Edwards MJ, van Wonderen JH, Casadevall C, Martel A, Jeuken LJC, Reisner E, Clarke TA, Butt JN. Bespoke Biomolecular Wires for Transmembrane Electron Transfer: Spontaneous Assembly of a Functionalized Multiheme Electron Conduit. Front Microbiol 2021; 12:714508. [PMID: 34484155 PMCID: PMC8415449 DOI: 10.3389/fmicb.2021.714508] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 07/12/2021] [Indexed: 11/13/2022] Open
Abstract
Shewanella oneidensis exchanges electrons between cellular metabolism and external redox partners in a process that attracts much attention for production of green electricity (microbial fuel cells) and chemicals (microbial electrosynthesis). A critical component of this pathway is the outer membrane spanning MTR complex, a biomolecular wire formed of the MtrA, MtrB, and MtrC proteins. MtrA and MtrC are decaheme cytochromes that form a chain of close-packed hemes to define an electron transfer pathway of 185 Å. MtrA is wrapped inside MtrB for solubility across the outer membrane lipid bilayer; MtrC sits outside the cell for electron exchange with external redox partners. Here, we demonstrate tight and spontaneous in vitro association of MtrAB with separately purified MtrC. The resulting complex is comparable with the MTR complex naturally assembled by Shewanella in terms of both its structure and rates of electron transfer across a lipid bilayer. Our findings reveal the potential for building bespoke electron conduits where MtrAB combines with chemically modified MtrC, in this case, labeled with a Ru-dye that enables light-triggered electron injection into the MtrC heme chain.
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Affiliation(s)
- Samuel E H Piper
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Marcus J Edwards
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Jessica H van Wonderen
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Carla Casadevall
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Lars J C Jeuken
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Erwin Reisner
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Thomas A Clarke
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Julea N Butt
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
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33
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Condition-Specific Molecular Network Analysis Revealed That Flagellar Proteins Are Involved in Electron Transfer Processes of Shewanella piezotolerans WP3. Genet Res (Camb) 2021; 2021:9953783. [PMID: 34456634 PMCID: PMC8371737 DOI: 10.1155/2021/9953783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 05/28/2021] [Accepted: 07/20/2021] [Indexed: 12/01/2022] Open
Abstract
Because of the ability to metabolize a large number of electron acceptors such as nitrate, nitrite, fumarate, and metal oxides, Shewanella species have attracted much attention in recent years. Generally, the use of these electron acceptors is mainly achieved through electron transfer proteins and their interactions which will dynamically change across different environmental conditions in cells. Therefore, functional analysis of condition-specific molecular networks can reveal biological information on electron transfer processes. By integrating expression data and molecular networks, we constructed condition-specific molecular networks for Shewanella piezotolerans WP3. We then identified condition-specific key genes and studied their potential functions with an emphasis on their roles in electron transfer processes. Functional module analysis showed that different flagellar assembly modules appeared under these conditions and suggested that flagellar proteins are important for these conditions. We also identified the electron transfer modules underlying these various environmental conditions. The present results could help with screening electron transfer genes and understanding electron transfer processes under various environmental conditions for the Shewanella species.
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Yu SS, Chen JJ, Cheng RF, Min Y, Yu HQ. Iron Cycle Tuned by Outer-Membrane Cytochromes of Dissimilatory Metal-Reducing Bacteria: Interfacial Dynamics and Mechanisms In Vitro. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:11424-11433. [PMID: 34319703 DOI: 10.1021/acs.est.1c01440] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The biogeochemical cycle of iron is of great importance to living organisms on Earth, and dissimilatory metal-reducing bacteria (DMRB) with the capability of reducing hematite (α-Fe2O3) by outer-membrane (OM) cytochromes play a great role in the iron cycle. However, the dynamic binding of cytochromes to α-Fe2O3 at the molecular level and the resulting impact on the photon-to-electron conversion of α-Fe2O3 for the iron cycle are not fully understood. To address these issues, two-dimensional IR correlation analysis coupled with molecular dynamics (MD) simulations was conducted for an OmcA-Fe2O3 system as OmcA bonds stronger with hematite in a typical DMRB,Shewanella. The photoelectric response of α-Fe2O3 with the OmcA coating was evaluated at three different potentials. Specifically, the binding groups from OmcA to α-Fe2O3 were in the sequence of carboxyl groups, amide II, and amide I. Further MD analysis reveals that both electrostatic interactions and hydrogen bonds played essential roles in the binding process, leading to the structural changes of OmcA to facilitate iron reduction. Moreover, the OmcA coating could store the photogenerated electrons from α-Fe2O3 like a capacitor and utilize the stored electrons for α-Fe2O3 reduction in dark and anoxic environments, further driving the biogeochemical cycle of iron. These investigations give the dynamic information on the OM protein/hematite interaction and provide fundamental insights into the biogeochemical cycle of iron by taking the photon-induced redox chemistry of iron oxide into consideration.
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Affiliation(s)
- 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
| | - Jie-Jie Chen
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Rui-Fen Cheng
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Yuan Min
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, 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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Edel M, Sturm G, Sturm-Richter K, Wagner M, Ducassou JN, Couté Y, Horn H, Gescher J. Extracellular riboflavin induces anaerobic biofilm formation in Shewanella oneidensis. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:130. [PMID: 34082787 PMCID: PMC8176591 DOI: 10.1186/s13068-021-01981-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/26/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Some microorganisms can respire with extracellular electron acceptors using an extended electron transport chain to the cell surface. This process can be applied in bioelectrochemical systems in which the organisms produce an electrical current by respiring with an anode as electron acceptor. These organisms apply flavin molecules as cofactors to facilitate one-electron transfer catalyzed by the terminal reductases and in some cases as endogenous electron shuttles. RESULTS In the model organism Shewanella oneidensis, riboflavin production and excretion trigger a specific biofilm formation response that is initiated at a specific threshold concentration, similar to canonical quorum-sensing molecules. Riboflavin-mediated messaging is based on the overexpression of the gene encoding the putrescine decarboxylase speC which leads to posttranscriptional overproduction of proteins involved in biofilm formation. Using a model of growth-dependent riboflavin production under batch and biofilm growth conditions, the number of cells necessary to produce the threshold concentration per time was deduced. Furthermore, our results indicate that specific retention of riboflavin in the biofilm matrix leads to localized concentrations, which by far exceed the necessary threshold value. CONCLUSION This study describes a new quorum-sensing mechanism in S. oneidensis. Biofilm formation of S. oneidensis is induced by low concentrations of riboflavin resulting in an upregulation of the ornithine-decarboxylase speC. The results can be applied for the development of strains catalyzing increased current densities in bioelectrochemical systems.
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Affiliation(s)
- Miriam Edel
- Institute for Applied Biosciences, Department of Applied Biology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Gunnar Sturm
- Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
| | - Katrin Sturm-Richter
- Institute for Applied Biosciences, Department of Applied Biology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Michael Wagner
- Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
| | | | - Yohann Couté
- University Grenoble Alpes, CEA, INSERM, IRIG, BGE, Grenoble, France
| | - Harald Horn
- Engler-Bunte-Institute, Water Chemistry and Water Technology, Karlsruhe Institute of Technology, Karlsruhe, Germany
- DVGW Research Laboratories for Water Chemistry and Water Technology, Karlsruhe, Germany
| | - Johannes Gescher
- Institute for Applied Biosciences, Department of Applied Biology, Karlsruhe Institute of Technology, Karlsruhe, Germany.
- Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany.
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Kouzuma A. Molecular mechanisms regulating the catabolic and electrochemical activities of Shewanella oneidensis MR-1. Biosci Biotechnol Biochem 2021; 85:1572-1581. [PMID: 33998649 DOI: 10.1093/bbb/zbab088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 04/17/2021] [Indexed: 11/14/2022]
Abstract
Electrochemically active bacteria (EAB) interact electrochemically with electrodes via extracellular electron transfer (EET) pathways. These bacteria have attracted significant attention due to their utility in environmental-friendly bioelectrochemical systems (BESs), including microbial fuel cells and electrofermentation systems. The electrochemical activity of EAB is dependent on their carbon catabolism and respiration; thus, understanding how these processes are regulated will provide insights into the development of a more efficient BES. The process of biofilm formation by EAB on BES electrodes is also important for electric current generation because it facilitates physical and electrochemical interactions between EAB cells and electrodes. This article summarizes the current knowledge on EET-related metabolic and cellular functions of a model EAB, Shewanella oneidensis MR-1, focusing specifically on regulatory systems for carbon catabolism, EET pathways, and biofilm formation. Based on recent developments, the author also discusses potential uses of engineered S. oneidensis strains for various biotechnological applications.
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Affiliation(s)
- Atsushi Kouzuma
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
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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: 22] [Impact Index Per Article: 7.3] [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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Ding D, Wu M, Liu Y. Genome-scale mutant fitness reveals versatile c-type cytochromes in Shewanella oneidensis MR-1. Mol Omics 2021; 17:288-295. [PMID: 33554980 DOI: 10.1039/d0mo00107d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Shewanella has been widely investigated for its metabolic versatility and use of a large number of extracellular electron acceptors. Many c-type cytochromes are responsible for this diversity, mainly in condition-specific fashions. By using genome-scale mutant fitness data, we studied which genes (particularly c-type cytochromes) were used to coordinate various electron transfer processes in the present work. First, by integrating fitness profiles with protein-protein interaction (PPI) networks, we showed that the genes with a high total fitness value were generally more important in PPI networks than those with low fitness values. Then, we identified genes that are important across many experiments, and further fitness analysis confirmed five versatile c-type cytochromes: ScyA (SO0264), PetC (SO0610), CcoP (SO2361), CcoO (SO2363) and CytcB (SO4666), which are considered to be crucial in most experimental conditions. Finally, we demonstrated a mediating role in the periplasm for the less-reported CytcB by combining protein structure, subcellular localization and disordered region analysis. Comparative genome analysis further revealed that it is distinctive in Shewanella species. Collectively, these results suggest that periplasmic electron transfer processes are more diverse and flexible than previously reported, giving insight for further experimental studies of Shewanella oneidensis MR-1.
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Affiliation(s)
- Dewu Ding
- School of Mathematics and Computer Science, Yichun University, Yichun, 336000, P. R. China.
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Zheng T, Xu B, Ji Y, Zhang W, Xin F, Dong W, Wei P, Ma J, Jiang M. Microbial fuel cell-assisted utilization of glycerol for succinate production by mutant of Actinobacillus succinogenes. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:23. [PMID: 33451363 PMCID: PMC7811241 DOI: 10.1186/s13068-021-01882-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 01/09/2021] [Indexed: 05/31/2023]
Abstract
BACKGROUND The global production of glycerol is increasing year by year since the demands of biodiesel is rising. It is benefit for high-yield succinate synthesis due to its high reducing property. A. succinogenes, a succinate-producing candidate, cannot grow on glycerol anaerobically, as it needs a terminal electron acceptor to maintain the balance of intracellular NADH and NAD+. Microbial fuel cell (MFC) has been widely used to release extra intracellular electrons. However, A. succinogenes is a non-electroactive strain which need the support of electron shuttle in MFC, and pervious research showed that acid-tolerant A. succinogenes has higher content of unsaturated fatty acids, which may be beneficial for the transmembrane transport of lipophilic electron shuttle. RESULTS MFC-assisted succinate production was evaluated using neutral red as an electron shuttle to recover the glycerol utilization. First, an acid-tolerant mutant JF1315 was selected by atmospheric and room temperature plasma (ARTP) mutagenesis aiming to improve transmembrane transport of neutral red (NR). Additionally, MFC was established to increase the ratio of oxidized NR to reduced NR. By combining these two strategies, ability of JF1315 for glycerol utilization was significantly enhanced, and 23.92 g/L succinate was accumulated with a yield of 0.88 g/g from around 30 g/L initial glycerol, along with an output voltage above 300 mV. CONCLUSIONS A novel MFC-assisted system was established to improve glycerol utilization by A. succinogenes for succinate and electricity production, making this system as a platform for chemicals production and electrical supply simultaneously.
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Affiliation(s)
- Tianwen Zheng
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800, P. R. China
| | - Bin Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800, P. R. China
| | - Yaliang Ji
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800, P. R. China
| | - Wenming Zhang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800, P. R. China
- Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800, P. R. China
| | - Fengxue Xin
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800, P. R. China
- Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800, P. R. China
| | - Weiliang Dong
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800, P. R. China
- Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800, P. R. China
| | - Ping Wei
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800, P. R. China
- Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800, P. R. China
| | - Jiangfeng Ma
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800, P. R. China.
- Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800, P. R. China.
| | - Min Jiang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800, P. R. China
- Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800, P. R. China
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Xiao X, Yu HQ. Molecular mechanisms of microbial transmembrane electron transfer of electrochemically active bacteria. Curr Opin Chem Biol 2020; 59:104-110. [DOI: 10.1016/j.cbpa.2020.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 06/14/2020] [Accepted: 06/15/2020] [Indexed: 10/23/2022]
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Beblawy S, Philipp LA, Gescher J. Accelerated Electro-Fermentation of Acetoin in Escherichia coli by Identifying Physiological Limitations of the Electron Transfer Kinetics and the Central Metabolism. Microorganisms 2020; 8:microorganisms8111843. [PMID: 33238546 PMCID: PMC7700339 DOI: 10.3390/microorganisms8111843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 11/19/2020] [Accepted: 11/21/2020] [Indexed: 11/16/2022] Open
Abstract
Anode-assisted fermentations offer the benefit of an anoxic fermentation routine that can be applied to produce end-products with an oxidation state independent from the substrate. The whole cell biocatalyst transfers the surplus of electrons to an electrode that can be used as a non-depletable electron acceptor. So far, anode-assisted fermentations were shown to provide high carbon efficiencies but low space-time yields. This study aimed at increasing space-time yields of an Escherichia coli-based anode-assisted fermentation of glucose to acetoin. The experiments build on an obligate respiratory strain, that was advanced using selective adaptation and targeted strain development. Several transfers under respiratory conditions led to point mutations in the pfl, aceF and rpoC gene. These mutations increased anoxic growth by three-fold. Furthermore, overexpression of genes encoding a synthetic electron transport chain to methylene blue increased the electron transfer rate by 2.45-fold. Overall, these measures and a medium optimization increased the space-time yield in an electrode-assisted fermentation by 3.6-fold.
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Affiliation(s)
- Sebastian Beblawy
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany; (S.B.); (L.-A.P.)
| | - Laura-Alina Philipp
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany; (S.B.); (L.-A.P.)
| | - Johannes Gescher
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany; (S.B.); (L.-A.P.)
- Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Correspondence:
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Engineering S. oneidensis for Performance Improvement of Microbial Fuel Cell-a Mini Review. Appl Biochem Biotechnol 2020; 193:1170-1186. [PMID: 33200267 DOI: 10.1007/s12010-020-03469-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 11/09/2020] [Indexed: 02/02/2023]
Abstract
Microbial fuel cell (MFC) is a promising technology that utilizes exoelectrogens cultivated in the form of biofilm to generate power from various types of sources supplied. A metal-reducing pathway is utilized by these organisms to transfer electrons obtained from the metabolism of substrate from anaerobic respiration extracellularly. A widely established model organism that is capable of extracellular electron transfer (EET) is Shewanella oneidensis. This review highlights the strategies used in the transformation of S. oneidensis and the recent development of MFC in terms of intervention through genetic modifications. S. oneidensis was genetically engineered for several aims including the study on the underlying mechanisms of EET, and the enhancement of power generation and wastewater treating potential when used in an MFC. Through engineering S. oneidensis, genes responsible for EET are identified and strategies on enhancing the EET efficiency are studied. Overexpressing genes related to EET to enhance biofilm formation, mediator biosynthesis, and respiration appears as one of the common approaches.
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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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Liu DF, Li WW. Potential-dependent extracellular electron transfer pathways of exoelectrogens. Curr Opin Chem Biol 2020; 59:140-146. [PMID: 32769012 DOI: 10.1016/j.cbpa.2020.06.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/10/2020] [Accepted: 06/13/2020] [Indexed: 10/23/2022]
Abstract
Exoelectrogens are distinct from other bacteria owing to their unique extracellular electron transfer (EET) abilities that allow for anaerobic respiration with various external redox-active surfaces, including electrode and metal oxides. Although the EET process is known to trigger diverse extracellular redox reactions, the reverse impact has been long overlooked. Recent evidences show that exoelectrogens can sense the potential changes of external surfaces and alter their EET strategies accordingly, which imparts them remarkable abilities in adapting to diverse and redox-variable environment. This mini-review provides a condensed overview and critical analysis about the recent discoveries on redox-dependent EET pathways of exoelectrogens, with focus on Geobacter sulfurreducens and Shewanella oneidensis. We summarize the detailed responses of various EET components, analyze the drives and mechanisms of such responses, highlight the diversity of EET dynamics among different bacterial species and under integrated effects of redox potential and surface chemistry, and discusses the future research needs.
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Affiliation(s)
- 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
| | - 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; USTC-City U Joint Advanced Research Center, Suzhou 215123, China.
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He X, Wu X, Qiao Y, Hu T, Wang D, Han X, Li CM. Electrical tension-triggered conversion of anaerobic to aerobic respiration of Shewanella putrefaciens CN32 cells while promoting biofilm growth in microbial fuel cells. Chem Commun (Camb) 2020; 56:6050-6053. [PMID: 32347873 DOI: 10.1039/d0cc01605e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A global gene expression analysis of Shewanella putrefaciens CN32 cells nearby a nanostructured microbial anode reveals an electrical tension-triggered conversion of anaerobic respiration to aerobic respiration with increased excretion of flavin electron shuttles and cytochrome C proteins, which sheds light on the role of electric tension in cell organisms.
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Affiliation(s)
- Xiu He
- Institute for Clean Energy & Advanced Materials, Faculty of Materials & Energy, Southwest University, No. 2 Tiansheng Road, Chongqing 400715, P. R. China.
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Philipp LA, Edel M, Gescher J. Genetic engineering for enhanced productivity in bioelectrochemical systems. ADVANCES IN APPLIED MICROBIOLOGY 2020; 111:1-31. [PMID: 32446410 DOI: 10.1016/bs.aambs.2020.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A shift from petrochemical processes toward a bio-based economy is one of the most advocated developments for a sustainable future. To achieve this will require the biotechnological production of platform chemicals that can be further processed by chemical engineering. Bioelectrochemical systems (BESs) are a novel tool within the biotechnology field. In BESs, microbes serve as biocatalysts for the production of biofuels and value-added compounds, as well as for the production of electricity. Although the general feasibility of bioelectrochemical processes has been demonstrated in recent years, much research has been conducted to develop biocatalysts better suited to meet industrial demands. Initially, mainly natural exoelectrogenic organisms were investigated for their performance in BESs. Driven by possibilities of recent developments in genetic engineering and synthetic biology, the spectrum of microbial catalysts and their versatility (substrate and product range) have expanded significantly. Despite these developments, there is still a tremendous gap between currently achievable space-time yields and current densities on the one hand and the theoretical limits of BESs on the other. It will be necessary to move the performance of the biocatalysts closer to the theoretical possibilities in order to establish viable production routines. This review summarizes the status quo of engineering microbial biocatalysts for anode-applications with high space-time yields. Furthermore, we will address some of the theoretical limitations of these processes exemplarily and discuss which of the present strategies might be combined to achieve highly synergistic effects and, thus, meet industrial demands.
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Affiliation(s)
- Laura-Alina Philipp
- Karlsruhe Institute of Technology, Institute for Applied Biosciences-Department of Applied Biology, Karlsruhe, Germany
| | - Miriam Edel
- Karlsruhe Institute of Technology, Institute for Applied Biosciences-Department of Applied Biology, Karlsruhe, Germany
| | - Johannes Gescher
- Karlsruhe Institute of Technology, Institute for Applied Biosciences-Department of Applied Biology, Karlsruhe, Germany; Karlsruhe Institute of Technology, Institute for Biological Interfaces, Eggenstein-Leopoldshafen, Germany.
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The Crystal Structure of a Biological Insulated Transmembrane Molecular Wire. Cell 2020; 181:665-673.e10. [PMID: 32289252 PMCID: PMC7198977 DOI: 10.1016/j.cell.2020.03.032] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 12/18/2019] [Accepted: 03/13/2020] [Indexed: 01/15/2023]
Abstract
A growing number of bacteria are recognized to conduct electrons across their cell envelope, and yet molecular details of the mechanisms supporting this process remain unknown. Here, we report the atomic structure of an outer membrane spanning protein complex, MtrAB, that is representative of a protein family known to transport electrons between the interior and exterior environments of phylogenetically and metabolically diverse microorganisms. The structure is revealed as a naturally insulated biomolecular wire possessing a 10-heme cytochrome, MtrA, insulated from the membrane lipidic environment by embedding within a 26 strand β-barrel formed by MtrB. MtrAB forms an intimate connection with an extracellular 10-heme cytochrome, MtrC, which presents its hemes across a large surface area for electrical contact with extracellular redox partners, including transition metals and electrodes. The 20 hemes of a 3-component complex are arranged to move electrons across 185 Å A β-barrel and 10-heme cytochrome form an insulated transmembrane nanowire An extracellular 10-heme cytochrome has a large surface area for electron exchange The hemes of both cytochromes are packed with a maximum inter-heme distance of 8 Å
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Wroblewska-Wolna AM, Harvie AJ, Rowe SF, Critchley K, Butt JN, Jeuken LJC. Quantum dot interactions with and toxicity to Shewanella oneidensis MR-1. NANOTECHNOLOGY 2020; 31:134005. [PMID: 31810073 DOI: 10.1088/1361-6528/ab5f78] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Combining abiotic photosensitisers such as quantum dots (QDs) with non-photosynthetic bacteria presents an intriguing concept into the design of artificial photosynthetic organisms and solar-driven fuel production. Shewanella oneidensis MR-1 (MR-1) is a versatile bacterium concerning respiration, metabolism and biocatalysis, and is a promising organism for artificial photosynthesis as the bacterium's synthetic and catalytic ability provides a potential system for bacterial biohydrogen production. MR-1's hydrogenases are present in the periplasmatic space. It follows that for photoenergised electrons to reach these enzymes, QDs will need to be able to enter the periplasm, or electrons need to enter the periplasm via the Mtr pathway that is responsible for MR-1's extracellular electron transfer ability. As a step towards this goal, various QDs were tested for their photo-reducing potential, nanotoxicology and further for their interaction with MR-1. CdTe/CdS/TGA, CdTe/CdS/Cysteamine, a commercial, negatively charged CdTe and CuInS2/ZnS/PMAL QDs were examined. The photoreduction potential of the QDs was confirmed by measuring their ability to photoreduce methyl viologen with different sacrificial electron donors. The commercial CdTe and CuInS2/ZnS/PMAL QDs showed no toxicity towards MR-1 as evaluated by a colony-forming units method and a fluorescence viability assay. Only the commercial negatively charged CdTe QDs showed good interaction with MR-1. With transmission electron microscopy, QDs were observed both in the cytoplasm and periplasm. These results inform on the possibilities and bottlenecks when developing bionanotechnological systems for the photosynthetic production of biohydrogen by MR-1.
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Kong G, Song D, Guo J, Sun G, Zhu C, Chen F, Yang Y, Xu M. Lack of Periplasmic Non-heme Protein SorA Increases Shewanella decolorationis Current Generation. Front Microbiol 2020; 11:262. [PMID: 32158435 PMCID: PMC7052111 DOI: 10.3389/fmicb.2020.00262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 02/04/2020] [Indexed: 11/13/2022] Open
Abstract
Bacterial extracellular electron transport (EET) plays an important role in many natural and engineering processes. Some periplasmic non-heme redox proteins usually coexist with c-type cytochromes (CTCs) during the EET process. However, in contrast to CTCs, little is known about the roles of these non-heme redox proteins in EET. In this study, the transcriptome of Shewanella decolorationis S12 showed that the gene encoding a periplasmic sulfite dehydrogenase molybdenum-binding subunit SorA was significantly up-regulated during electrode respiration in microbial fuel cells (MFCs) compared with that during azo-dye reduction. The maximum current density of MFCs catalyzed by a mutant strain lacking SorA (ΔsorA) was 25% higher than that of wild strain S12 (20 vs. 16 μA/cm2). Both biofilm formation and the current generation of the anodic biofilms were increased by the disruption of sorA, which suggests that the existence of SorA in S. decolorationis S12 inhibits electrode respiration. In contrast, disruption of sorA had no effect on respiration by S. decolorationis S12 with oxygen, fumarate, azo dye, or ferric citrate as electron acceptors. This is the first report of the specific effect of a periplasmic non-heme redox protein on EET to electrode and provides novel information for enhancing bacterial current generation.
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Affiliation(s)
- Guannan Kong
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
- Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China
| | - Da Song
- Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China
| | - Jun Guo
- Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China
| | - Guoping Sun
- Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Chunjie Zhu
- Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Fusheng Chen
- College of Food Science and Technology, Henan University of Technology, Zhengzhou, China
| | - Yonggang Yang
- Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangzhou, China
| | - Meiying Xu
- Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China
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