1
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Klein EM, Heintz H, Wurst R, Schuldt S, Hähl H, Jacobs K, Gescher J. Comparative analysis of the influence of BpfA and BpfG on biofilm development and current density in Shewanella oneidensis under oxic, fumarate- and anode-respiring conditions. Sci Rep 2024; 14:23174. [PMID: 39369013 PMCID: PMC11455927 DOI: 10.1038/s41598-024-73474-w] [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: 07/18/2024] [Accepted: 09/17/2024] [Indexed: 10/07/2024] Open
Abstract
Biofilm formation by Shewanella oneidensis has been extensively studied under oxic conditions; however, relatively little is known about biofilm formation under anoxic conditions and how biofilm architecture and composition can positively influence current generation in bioelectrochemical systems. In this study, we utilized a recently developed microfluidic biofilm analysis setup with automated 3D imaging to investigate the effects of extracellular electron acceptors and synthetic modifications to the extracellular polymeric matrix on biofilm formation. Our results with the wild type strain demonstrate robust biofilm formation even under anoxic conditions when fumarate is used as the electron acceptor. However, this pattern shifts when a graphite electrode is employed as the electron acceptor, resulting in biofilm formation falling below the detection limit of the optical coherence tomography imaging system. To manipulate biofilm formation, we aimed to express BpfG with a single amino acid substitution in the catalytic center (C116S) and to overexpress bpfA. Our analyses indicate that, under oxic conditions, overarching mechanisms predominantly influence biofilm development, rather than the specific mutations we investigated. Under anoxic conditions, the bpfG mutation led to a quantitative increase in biofilm formation, but both strains exhibited significant qualitative changes in biofilm architecture compared to the controls. When an anode was used as the sole electron acceptor, both the bpfA and bpfG mutations positively impacted mean current density, yielding a 1.8-fold increase for each mutation.
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Affiliation(s)
- Edina Marlen Klein
- Institute of Technical Microbiology, University of Technology Hamburg, 21073, Hamburg, Germany
| | - Hannah Heintz
- Experimental Physics, Center for Biophysics, Saarland University, 66123, Saarbrücken, Germany
| | - René Wurst
- Institute of Technical Microbiology, University of Technology Hamburg, 21073, Hamburg, Germany
| | - Simon Schuldt
- Institute of Technical Microbiology, University of Technology Hamburg, 21073, Hamburg, Germany
| | - Hendrik Hähl
- Experimental Physics, Center for Biophysics, Saarland University, 66123, Saarbrücken, Germany
| | - Karin Jacobs
- Experimental Physics, Center for Biophysics, Saarland University, 66123, Saarbrücken, Germany
- Max Planck School Matter to Life, 69120, Heidelberg, Germany
| | - Johannes Gescher
- Institute of Technical Microbiology, University of Technology Hamburg, 21073, Hamburg, Germany.
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2
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McCuskey SR, Quek G, Vázquez RJ, Kundukad B, Bin Ismail MH, Astorga SE, Jiang Y, Bazan GC. Evolving Synergy Between Synthetic and Biotic Elements in Conjugated Polyelectrolyte/Bacteria Composite Improves Charge Transport and Mechanical Properties. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2405242. [PMID: 39262122 DOI: 10.1002/advs.202405242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Revised: 07/29/2024] [Indexed: 09/13/2024]
Abstract
gLiving materials can achieve unprecedented function by combining synthetic materials with the wide range of cellular functions. Of interest are situations where the critical properties of individual abiotic and biotic elements improve via their combination. For example, integrating electroactive bacteria into conjugated polyelectrolyte (CPE) hydrogels increases biocurrent production. One observes more efficient electrical charge transport within the CPE matrix in the presence of Shewanella oneidensis MR-1 and more current per cell is extracted, compared to traditional biofilms. Here, the origin of these synergistic effects are examined. Transcriptomics reveals that genes in S. oneidensis MR-1 related to bacteriophages and energy metabolism are upregulated in the composite material. Fluorescent staining and rheological measurements before and after enzymatic treatment identified the importance of extracellular biomaterials in increasing matrix cohesion. The synergy between CPE and S. oneidensis MR-1 thus arises from initially unanticipated changes in matrix composition and bacteria adaption within the synthetic environment.
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Affiliation(s)
- Samantha R McCuskey
- Department of Chemistry and Chemical & Biomolecular Engineering, National University of Singapore, Singapore, 119077, Singapore
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore, 637551, Singapore
| | - Glenn Quek
- Department of Chemistry and Chemical & Biomolecular Engineering, National University of Singapore, Singapore, 119077, Singapore
| | - Ricardo Javier Vázquez
- Institute for Functional Intelligent Materials (I-FIM), National University of Singapore, Singapore, 117544, Singapore
| | - Binu Kundukad
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore, 637551, Singapore
| | - Muhammad Hafiz Bin Ismail
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore, 637551, Singapore
| | - Solange E Astorga
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore, 637551, Singapore
| | - Yan Jiang
- Department of Chemistry and Chemical & Biomolecular Engineering, National University of Singapore, Singapore, 119077, Singapore
| | - Guillermo C Bazan
- Department of Chemistry and Chemical & Biomolecular Engineering, National University of Singapore, Singapore, 119077, Singapore
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore, 637551, Singapore
- Institute for Functional Intelligent Materials (I-FIM), National University of Singapore, Singapore, 117544, Singapore
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3
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Agee A, Pace G, Yang V, Segalman R, Furst AL. Mixed Conducting Polymers Alter Electron Transfer Thermodynamics to Boost Current Generation from Electroactive Microbes. J Am Chem Soc 2024; 146:19728-19736. [PMID: 39001879 PMCID: PMC11276794 DOI: 10.1021/jacs.4c01288] [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: 01/26/2024] [Revised: 06/30/2024] [Accepted: 07/02/2024] [Indexed: 07/15/2024]
Abstract
Electroactive microbes that can release or take up electrons are essential components of nearly every ecological niche and are powerful tools for the development of alternative energy technologies. Small-molecule mediators are critical for this electron transfer but remain difficult to study and engineer because they perform concerted two-electron transfer in native systems but only individual, one-electron transfers in electrochemical studies. Here, we report that electrode modification with ion- and electron-conductive polymers yields biosimilar, concerted two-electron transfer from Shewanella oneidensis via flavin mediators. S. oneidensis biofilms on these polymers show significantly improved per-microbe current generation and morphologies that more closely resemble native systems, setting a new paradigm for the study and optimization of these electron transfer processes. The unprecedented concerted electron transfer was found to be due to altered mediator electron transfer thermodynamics, enabling biologically relevant studies of electroactive biofilms in the lab for the first time. These important findings pave the way for a complete understanding of the ecological role of electroactive microbes and their broad application in sustainable technologies.
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Affiliation(s)
- Alec Agee
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - Gordon Pace
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Victoria Yang
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - Rachel Segalman
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Ariel L. Furst
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
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4
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Klein E, Wurst R, Rehnlund D, Gescher J. Elucidating the development of cooperative anode-biofilm-structures. Biofilm 2024; 7:100193. [PMID: 38601817 PMCID: PMC11004076 DOI: 10.1016/j.bioflm.2024.100193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 03/13/2024] [Accepted: 03/21/2024] [Indexed: 04/12/2024] Open
Abstract
Microbial electrochemical systems are a highly versatile platform technology with a particular focus on the interplay of chemical and electrical energy conversion and offer immense potential for a sustainable bioeconomy. The industrial realization of this potential requires a critical focus on biofilm optimization if performance is to be controlled over a long period of time. Moreover, the aspect and influence of cooperativity has to be addressed as many applied anodic bioelectrochemical systems will most likely be operated with a diversity of interacting microbial species. Hence, the aim of this study was to analyze how interspecies dependence and cooperativity of a model community influence the development of anodic biofilms. To investigate biofilm activity in a spatially resolved manner, a microfluidic bioelectrochemical flow cell was developed that can be equipped with user-defined electrode materials and operates under laminar flow conditions. With this infrastructure, the development of single and co-culture biofilms of the two model organisms Shewanella oneidensis and Geobacter sulfurreducens on graphite electrodes was monitored by optical coherence tomography analysis. The interdependence in the co-culture biofilm was achieved by feeding the community with lactate, which is converted by S. oneidensis into acetate, which in turn serves as substrate for G. sulfurreducens. The results show that co-cultivation resulted in the formation of denser biofilms than in single culture. Moreover, we hypothesize that S. oneidensis in return utilizes the conductive biofilm matrix build by G. sulfurreducens for direct interspecies electron transfer (DIET) to the anode. FISH analysis revealed that the biofilms consisted of approximately two-thirds G. sulfurreducens cells, which most likely formed a conductive 3D network throughout the biofilm matrix, in which evenly distributed tubular S. oneidensis colonies were embedded without direct contact to the anode surface. Live/dead staining shows that the outermost biofilm contained almost exclusively dead cells (98 %), layers near the anode contained 45-56 % and the entire biofilm contained 82 % live cells. Our results exemplify how the architecture of the exoelectrogenic biofilm dynamically adapts to the respective process conditions.
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Affiliation(s)
- Edina Klein
- Institute of Technical Microbiology, University of Technology Hamburg, Hamburg, Germany
| | - René Wurst
- Institute of Technical Microbiology, University of Technology Hamburg, Hamburg, Germany
| | - David Rehnlund
- Department of Chemistry – Ångström Laboratory, Uppsala University, Box 538, SE-751 21, Uppsala, Sweden
| | - Johannes Gescher
- Institute of Technical Microbiology, University of Technology Hamburg, Hamburg, Germany
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Kou B, Yuan Y, Zhu X, Ke Y, Wang H, Yu T, Tan W. Effect of soil organic matter-mediated electron transfer on heavy metal remediation: Current status and perspectives. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 917:170451. [PMID: 38296063 DOI: 10.1016/j.scitotenv.2024.170451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 01/18/2024] [Accepted: 01/24/2024] [Indexed: 02/05/2024]
Abstract
Soil contamination by heavy metals poses major risks to human health and the environment. Given the current status of heavy metal pollution, many remediation techniques have been tested at laboratory and contaminated sites. The effects of soil organic matter-mediated electron transfer on heavy metal remediation have not been adequately studied, and the key mechanisms underlying this process have not yet been elucidated. In this review, microbial extracellular electron transfer pathways, organic matter electron transfer for heavy metal reduction, and the factors affecting these processes were discussed to enhance our understanding of heavy metal pollution. It was found that microbial extracellular electrons delivered by electron shuttles have the longest distance among the three electron transfer pathways, and the application of exogenous electron shuttles lays the foundation for efficient and persistent remediation of heavy metals. The organic matter-mediated electron transfer process, wherein organic matter acts as an electron shuttle, promotes the conversion of high valence state metal ions, such as Cr(VI), Hg(II), and U(VI), into less toxic and morphologically stable forms, which inhibits their mobility and bioavailability. Soil type, organic matter structural and content, heavy metal concentrations, and environmental factors (e.g., pH, redox potential, oxygen conditions, and temperature) all influence organic matter-mediated electron transfer processes and bioremediation of heavy metals. Organic matter can more effectively mediate electron transfer for heavy metal remediation under anaerobic conditions, as well as when the heavy metal content is low and the redox potential is suitable under fluvo-aquic/paddy soil conditions. Organic matter with high aromaticity, quinone groups, and phenol groups has a stronger electron transfer ability. This review provides new insights into the control and management of soil contamination and heavy metal remediation technologies.
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Affiliation(s)
- Bing Kou
- College of Urban and Environmental Science, Northwest University, Xi'an 710127, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Ying Yuan
- State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Xiaoli Zhu
- College of Urban and Environmental Science, Northwest University, Xi'an 710127, China.
| | - Yuxin Ke
- College of Urban and Environmental Science, Northwest University, Xi'an 710127, China
| | - Hui Wang
- State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Tingqiao Yu
- International Education College, Beijing Vocational College of Agriculture, Beijing 102442, China
| | - Wenbing Tan
- State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
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6
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Grenfell AW, Intile PJ, McFarlane JA, Leung DC, Abdalla K, Wold MC, Kees ED, Gralnick JA. The Outer Membrane Cytochrome OmcA Is Essential for Infection of Shewanella oneidensis by a Zebrafish-Associated Bacteriophage. J Bacteriol 2023; 205:e0046922. [PMID: 37227287 PMCID: PMC10294696 DOI: 10.1128/jb.00469-22] [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: 12/07/2022] [Accepted: 04/25/2023] [Indexed: 05/26/2023] Open
Abstract
The microbiota-the mixture of microorganisms in the intestinal tract of animals-plays an important role in host biology. Bacteriophages are a prominent, though often overlooked, component of the microbiota. The mechanisms that phage use to infect susceptible cells associated with animal hosts, and the broader role they could play in determining the substituents of the microbiota, are poorly understood. In this study, we isolated a zebrafish-associated bacteriophage, which we named Shewanella phage FishSpeaker. This phage infects Shewanella oneidensis strain MR-1, which cannot colonize zebrafish, but it is unable to infect Shewanella xiamenensis strain FH-1, a strain isolated from the zebrafish gut. Our data suggest that FishSpeaker uses the outer membrane decaheme cytochrome OmcA, which is an accessory component of the extracellular electron transfer (EET) pathway in S. oneidensis, as well as the flagellum to recognize and infect susceptible cells. In a zebrafish colony that lacks detectable FishSpeaker, we found that most Shewanella spp. are sensitive to infection and that some strains are resistant to infection. Our results suggest that phage could act as a selectivity filter for zebrafish-associated Shewanella and show that the EET machinery can be targeted by phage in the environment. IMPORTANCE Phage exert selective pressure on bacteria that influences and shapes the composition of microbial populations. However, there is a lack of native, experimentally tractable systems for studying how phage influence microbial population dynamics in complex communities. Here, we show that a zebrafish-associated phage requires both the outer membrane-associated extracellular electron transfer protein OmcA and the flagellum to infect Shewanella oneidensis strain MR-1. Our results suggest that the newly discovered phage-FishSpeaker-could exert selective pressure that restricts which Shewanella spp. colonize zebrafish. Moreover, the requirement of OmcA for infection by FishSpeaker suggests that the phage preferentially infects cells that are oxygen limited, a condition required for OmcA expression and an ecological feature of the zebrafish gut.
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Affiliation(s)
- Andrew W. Grenfell
- 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
| | - Peter J. Intile
- 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
| | - John A. McFarlane
- 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
| | - Dani C. Leung
- 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
| | - Khalid Abdalla
- 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
| | - Michael C. Wold
- 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
| | - Eric D. Kees
- 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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7
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Sweet P, Blacutt J, Gordon V, Contreras L. Exposure of Shewanella oneidensis MR-1 to Sublethal Doses of Ionizing Radiation Triggers Short-Term SOS Activation and Longer-Term Prophage Activation. Appl Environ Microbiol 2023; 89:e0171622. [PMID: 36847540 PMCID: PMC10057963 DOI: 10.1128/aem.01716-22] [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: 10/17/2022] [Accepted: 01/23/2023] [Indexed: 03/01/2023] Open
Abstract
Currently, there is a lack of bacterial biomarkers indicative of exposure to ionizing radiation (IR). IR biomarkers have applications for medical treatment planning, population exposure surveillance, and IR sensitivity studies. In this study, we compared the utility of signals originating from prophages and the SOS regulon as biomarkers of IR exposure in the radiosensitive bacterium Shewanella oneidensis. Using RNA sequencing, we demonstrated that 60 min after exposure to acute doses of IR (40, 1, 0.5, and 0.25 Gy), the transcriptional activation of the SOS regulon and the lytic cycle of the T-even lysogenic prophage So Lambda are comparable. Using quantitative PCR (qPCR), we showed that 300 min after exposure to doses as low as 0.25 Gy, the fold change of transcriptional activation of the So Lambda lytic cycle surpassed that of the SOS regulon. We observed an increase in cell size (a phenotype of SOS activation) and plaque production (a phenotype of prophage maturation) 300 min after doses as low as 1 Gy. While the transcriptional responses of the SOS and So Lambda regulons have been examined in S. oneidensis after lethal IR exposures, the potential of these (and other transcriptome-wide) responses as biomarkers of sublethal levels of IR (<10 Gy) and the longer-term activity of these two regulons have not been investigated. A major finding is that after exposure to sublethal doses of IR, the most upregulated transcripts are associated with a prophage regulon and not with a DNA damage response. Our findings suggest that prophage lytic cycle genes are a promising source of biomarkers of sublethal DNA damage. IMPORTANCE The bacterial minimum threshold of sensitivity to ionizing radiation (IR) is poorly understood, which hinders our understanding of how living systems recover from the doses of IR experienced in medical, industrial, and off-world environments. Using a transcriptome-wide approach, we studied how in the highly radiosensitive bacterium S. oneidensis, genes (including the SOS regulon and the So Lambda prophage) are activated after exposure to low doses of IR. We found that 300 min after exposure to doses as low as 0.25 Gy, genes within the So Lambda regulon remained upregulated. As this is the first transcriptome-wide study of how bacteria respond to acute sublethal doses of IR, these findings serve as a benchmark for future bacterial IR sensitivity studies. This is the first work to highlight the utility of prophages as biomarkers of exposure to very low (i.e., sublethal) doses of IR and to examine the longer-term impacts of sublethal IR exposure on bacteria.
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Affiliation(s)
- Philip Sweet
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Jacob Blacutt
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Vernita Gordon
- Department of Physics, Center for Nonlinear Dynamics, The University of Texas at Austin, Austin, Texas, USA
| | - Lydia Contreras
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas, USA
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8
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Szmuc E, Walker DJF, Kireev D, Akinwande D, Lovley DR, Keitz B, Ellington A. Engineering Geobacter pili to produce metal:organic filaments. Biosens Bioelectron 2023; 222:114993. [PMID: 36525710 DOI: 10.1016/j.bios.2022.114993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/15/2022] [Accepted: 12/06/2022] [Indexed: 12/12/2022]
Abstract
The organized self-assembly of conductive biological structures holds promise for creating new bioelectronic devices. In particular, Geobacter sulfurreducens type IVa pili have proven to be a versatile material for fabricating protein nanowire-based devices. To scale the production of conductive pili, we designed a strain of Shewanella oneidensis that heterologously expressed abundant, conductive Geobacter pili when grown aerobically in liquid culture. S. oneidensis expressing a cysteine-modified pilin, designed to enhance the capability to bind to gold, generated conductive pili that self-assembled into biohybrid filaments in the presence of gold nanoparticles. Elemental composition analysis confirmed the filament-metal interactions within the structures, which were several orders of magnitude larger than previously described metal:organic filaments. The results demonstrate that the S. oneidensis chassis significantly advances the possibilities for facile conductive protein nanowire design and fabrication.
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Affiliation(s)
- Eric Szmuc
- College of Natural Sciences, University of Texas at Austin, Austin, TX, 78712, United States
| | - David J F Walker
- College of Natural Sciences, University of Texas at Austin, Austin, TX, 78712, United States; U.S. Army Engineer Research and Development Center, Environmental Laboratory, University of Texas at Austin, Austin, TX, 78712, United States; Bioconscientia LLC, Austin, TX 78712, United States
| | - Dmitry Kireev
- Cockrell School of Engineering, University of Texas at Austin, Austin, TX, 78712, United States
| | - Deji Akinwande
- Cockrell School of Engineering, University of Texas at Austin, Austin, TX, 78712, United States
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, MA, 01003, United States
| | - Benjamin Keitz
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, United States
| | - Andrew Ellington
- College of Natural Sciences, University of Texas at Austin, Austin, TX, 78712, United States.
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9
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Sun S, Zhang M, Gu X, Yan P, He S, Chachar A. New insight and enhancement mechanisms for Feammox process by electron shuttles in wastewater treatment - A systematic review. BIORESOURCE TECHNOLOGY 2023; 369:128495. [PMID: 36526117 DOI: 10.1016/j.biortech.2022.128495] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 12/11/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
Ammonium oxidation coupled to Fe(III) reduction (Feammox) is a newly discovered iron-nitrogen cycle process of microbial catalyzed NH4+ oxidation coupled with iron reduction. Fe(III) often exists in the form of insoluble iron minerals resulting in reduced microbial availability and low efficiency of Feammox. Electron shuttles(ESs) can be reversibly oxidized and reduced which has the potential to improve Feammox efficiency. This review summarizes the discovery process, electron transfer mechanism, influencing factors and driven microorganisms of Feammox, ang expounds the possibility and potential mechanism of ESs to enhance Feammox efficiency. Based on an in-depth analysis of the current research situation of Feammox for nitrogen removal, the knowledge gaps and future research directions including how to apply ESs enhanced Feammox to promote nitrogen removal in practical wastewater treatment have been highlighted. This review can provide new ideas for the engineering application research of Feammox and strong theoretical support for its development.
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Affiliation(s)
- Shanshan Sun
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China
| | - Manping Zhang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China
| | - Xushun Gu
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China
| | - Pan Yan
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China
| | - Shengbing He
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 20092, PR China; Shanghai Engineering Research Center of Landscape Water Environment, Shanghai 200031, PR China.
| | - Azharuddin Chachar
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China
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10
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Torres-Rojas F, Muñoz D, Pía Canales C, Vargas IT. Bioprospecting for electrochemically active perchlorate-reducing microorganisms. Bioelectrochemistry 2022; 147:108171. [DOI: 10.1016/j.bioelechem.2022.108171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/23/2022] [Accepted: 05/28/2022] [Indexed: 11/29/2022]
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11
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Wu Y, Wang C, Wang S, An J, Liang D, Zhao Q, Tian L, Wu Y, Wang X, Li N. Graphite accelerate dissimilatory iron reduction and vivianite crystal enlargement. WATER RESEARCH 2021; 189:116663. [PMID: 33307376 DOI: 10.1016/j.watres.2020.116663] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 11/11/2020] [Accepted: 11/20/2020] [Indexed: 06/12/2023]
Abstract
Biomineralized vivianite induced by dissimilatory iron reduction bacteria (DIRB) has received increasing attention because it alleviates phosphorus crisis and phosphorus pollution simultaneously. However, the relatively small crystal size and low Fe(III) reduction rate restrict the separation and recovery of vivianite. In this study, graphite was selected as additive to enhance vivianite biomineralization with soluble ferric citrate and insoluble hematite as two representative electron acceptors. As soluble ferric citrate provided abundant accessible electron acceptors, relatively inconspicuous increase (lower than 7%) was observed for graphite on vivianite formation while inoculated with raw sewage or DIRB. In contrast, graphite considerably increased vivianite formation efficiency by 23% in insoluble hematite inoculated with raw sewage. The graphite promotion on vivianite formation in hematite batch was magnified to 70% by DIRB. Dosing hematite inhibited the supply of electron acceptors, while conductive graphite promoted the electrical connection between minerals and DIRB, thus improved the Fe(III) reduction rate and efficiency. In addition, secondary minerals in hematite exhibited a larger aspect ratio and tended to aggregate on graphite. Graphite enlarged the vivianite size in hematite from 10 µm to 90 µm due to aggregation. Enhancing dissimilatory iron reduction (DIR) rate of iron oxides and enlarging crystal size provide new insights for vivianite formation and separation during wastewater treatment.
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Affiliation(s)
- Yu Wu
- School of Environmental Science and Engineering, Tianjin University, No. 35 Yaguan Road, Jinnan District, Tianjin 300350, China
| | - Cong Wang
- School of Environmental Science and Engineering, Tianjin University, No. 35 Yaguan Road, Jinnan District, Tianjin 300350, China
| | - Shu Wang
- School of Environmental Science and Engineering, Tianjin University, No. 35 Yaguan Road, Jinnan District, Tianjin 300350, China
| | - Jingkun An
- School of Environmental Science and Engineering, Tianjin University, No. 35 Yaguan Road, Jinnan District, Tianjin 300350, China
| | - Danhui Liang
- School of Environmental Science and Engineering, Tianjin University, No. 35 Yaguan Road, Jinnan District, Tianjin 300350, China
| | - Qian Zhao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Lili Tian
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Yue Wu
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Xin Wang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Nan Li
- School of Environmental Science and Engineering, Tianjin University, No. 35 Yaguan Road, Jinnan District, Tianjin 300350, China.
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12
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Dundas CM, Walker DJ, Keitz BK. Tuning Extracellular Electron Transfer by Shewanella oneidensis Using Transcriptional Logic Gates. ACS Synth Biol 2020; 9:2301-2315. [PMID: 32786362 DOI: 10.1021/acssynbio.9b00517] [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] [Indexed: 11/28/2022]
Abstract
Extracellular electron transfer (EET) pathways, such as those in the bacterium Shewanella oneidensis, interface cellular metabolism with a variety of redox-driven applications. However, designer control over EET flux in S. oneidensis has proven challenging because a functional understanding of its EET pathway proteins and their effect on engineering parametrizations (e.g., response curves, dynamic range) is generally lacking. To address this, we systematically altered transcription and translation of single genes encoding parts of the primary EET pathway of S. oneidensis, CymA/MtrCAB, and examined how expression differences affected model-fitted parameters for Fe(III) reduction kinetics. Using a suite of plasmid-based inducible circuits maintained by appropriate S. oneidensis knockout strains, we pinpointed construct/strain pairings that expressed cymA, mtrA, and mtrC with maximal dynamic range of Fe(III) reduction rate. These optimized EET gene constructs were employed to create Buffer and NOT gate architectures that predictably turn on and turn off EET flux, respectively, in response to isopropyl β-D-1-thiogalactopyranoside (IPTG). Furthermore, we found that response functions generated by these logic gates (i.e., EET activity vs inducer concentration) were comparable to those generated by conventional synthetic biology circuits, where fluorescent reporters are the output. Our results provide insight on programming EET activity with transcriptional logic gates and suggest that previously developed transcriptional circuitry can be adapted to predictably control EET flux.
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Affiliation(s)
- Christopher M. Dundas
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - David J.F. Walker
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, United States
| | - Benjamin K. Keitz
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
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13
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Wu Y, Luo X, Qin B, Li F, Häggblom MM, Liu T. Enhanced Current Production by Exogenous Electron Mediators via Synergy of Promoting Biofilm Formation and the Electron Shuttling Process. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:7217-7225. [PMID: 32352288 DOI: 10.1021/acs.est.0c00141] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Exogenous electron mediators (EMs) can facilitate extracellular electron transfer (EET) via electron shuttling processes, but it is still unclear whether and how biofilm formation is affected by the presence of EMs. Here, the impacts of EMs on EET and biofilm formation were investigated in bioelectrochemical systems (BESs) with Shewanella oneidensis MR-1, and the results showed that the presence of five different EMs led to high density current production. All the EMs substantially promoted biofilm formation with 15-36 times higher total biofilm DNA with EMs than without EMs, and they also increased the production of extracellular polymeric substances, which was favorable for biofilm formation. The current decreased substantially after removing EMs from the medium or by replacing electrodes without biofilm, suggesting that both biofilm and EMs are required for high density current production. EET-related gene expression was upregulated with EMs, resulting in the high flux of cell electron output. A synergistic mechanism was proposed: EMs in suspension were quickly reduced by the cells and reoxidized rapidly by the electrode, resulting in a microenvironment with sufficient oxidized EMs for biofilm formation, and thus, besides the well-known electron shuttling process, the EM-induced high biofilm formation and high Mtr gene expression could jointly contribute to the EET and subsequently produce a high density current. This study provides a new insight into EM-enhanced current production via regulating the biofilm formation and EET-related gene expression.
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Affiliation(s)
- Yundang Wu
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science and Technology, Guangdong Academy of Sciences, Guangzhou 510650, P. R. China
| | - Xiaobo Luo
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science and Technology, Guangdong Academy of Sciences, Guangzhou 510650, P. R. China
- Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Baoli Qin
- College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Fangbai Li
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science and Technology, Guangdong Academy of Sciences, Guangzhou 510650, P. R. China
| | - Max M Häggblom
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, United States
| | - Tongxu Liu
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science and Technology, Guangdong Academy of Sciences, Guangzhou 510650, P. R. China
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangzhou 510650, China
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14
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Su L, Fukushima T, Ajo-Franklin CM. A hybrid cyt c maturation system enhances the bioelectrical performance of engineered Escherichia coli by improving the rate-limiting step. Biosens Bioelectron 2020; 165:112312. [PMID: 32729471 DOI: 10.1016/j.bios.2020.112312] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/15/2020] [Accepted: 05/18/2020] [Indexed: 12/26/2022]
Abstract
Bioelectronic devices can use electron flux to enable communication between biotic components and abiotic electrodes. We have modified Escherichia coli to electrically interact with electrodes by expressing the cytochrome c from Shewanella oneidensis MR-1. However, we observe inefficient electrical performance, which we hypothesize is due to the limited compatibility of the E. coli cytochrome c maturation (Ccm) systems with MR-1 cytochrome c. Here we test whether the bioelectronic performance of E. coli can be improved by constructing hybrid Ccm systems containing protein domains from both E. coli and S. oneidensis MR-1. The hybrid CcmH increased cytochrome c expression by increasing the abundance of CymA 60%, while only slightly changing the abundance of the other cytochromes c. Electrochemical measurements showed that the overall current from the hybrid ccm strain increased 121% relative to the wildtype ccm strain, with an electron flux per cell of 12.3 ± 0.3 fA·cell-1. Additionally, the hybrid ccm strain doubled its electrical response with the addition of exogenous flavin, and quantitative analysis of this demonstrates CymA is the rate-limiting step in this electron conduit. These results demonstrate that this hybrid Ccm system can enhance the bioelectrical performance of the cyt c expressing E. coli, allowing the construction of more efficient bioelectronic devices.
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Affiliation(s)
- Lin Su
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210018, China; Department of BioSciences, Rice University, Houston, TX, 77005, USA; Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Tatsuya Fukushima
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Caroline M Ajo-Franklin
- Department of BioSciences, Rice University, Houston, TX, 77005, USA; Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA; Molecular Biophysics and Integrated Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA; Institute for Biosciences and Bioengineering, Rice University, Houston, TX, 77005, USA.
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15
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Ancona V, Campanale C, Tumolo M, De Paola D, Ardito C, Volpe A, Uricchio VF. Enhancement of Chromium (VI) Reduction in Microcosms Amended with Lactate or Yeast Extract: A Laboratory-Scale Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17030704. [PMID: 31973238 PMCID: PMC7037453 DOI: 10.3390/ijerph17030704] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 01/16/2020] [Accepted: 01/19/2020] [Indexed: 12/19/2022]
Abstract
A laboratory-scale study was carried out to evaluate the groundwater bioremediation potential of hexavalent chromium (Cr(VI)), taking into account the chromate pollution of an industrial site located in Southern Italy (Apulia Region). The reduction of Cr(VI) was studied on laboratory microcosms, set up in different experimental conditions, namely: ABIO (soil and water sterilized), BIO (soil and water not sterilized), LATT (with the addition of lactate), and YE (with the addition of yeast extract). Control test lines, set up by using sterilized matrices and amendments, were employed to assess the occurrence of the pollutant reduction via chemical processes. By combining molecular (microbial abundance, specific chromate reductase genes (ChR) and the Shewanella oinedensis bacterial strain) with chemical analyses of chromium (VI and III) in the matrices (water and soil) of each microcosm, it was possible to investigate the response of microbial populations to different experimental conditions, and therefore, to assess their bioremediation capability in promoting Cr(VI) reduction. The overall results achieved within this work evidenced the key role of amendments (lactate and yeast extract) in enhancing the biological reduction of hexavalent chromium in the contaminated aqueous phase of laboratory microcosms. The highest value of Cr(VI) removal (99.47%) was obtained in the YE amended microcosms at seven days.
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Affiliation(s)
- Valeria Ancona
- Water Research Institute-Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy; (C.C.); (M.T.); (C.A.); (A.V.); (V.F.U.)
- Correspondence:
| | - Claudia Campanale
- Water Research Institute-Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy; (C.C.); (M.T.); (C.A.); (A.V.); (V.F.U.)
| | - Marina Tumolo
- Water Research Institute-Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy; (C.C.); (M.T.); (C.A.); (A.V.); (V.F.U.)
| | - Domenico De Paola
- Institute of Biosciences and Bioresources, Italian National Research Council (IBBR-CNR), 70126 Bari, Italy;
| | - Claudio Ardito
- Water Research Institute-Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy; (C.C.); (M.T.); (C.A.); (A.V.); (V.F.U.)
| | - Angela Volpe
- Water Research Institute-Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy; (C.C.); (M.T.); (C.A.); (A.V.); (V.F.U.)
| | - Vito Felice Uricchio
- Water Research Institute-Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy; (C.C.); (M.T.); (C.A.); (A.V.); (V.F.U.)
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16
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Beblawy S, Bursac T, Paquete C, Louro R, Clarke TA, Gescher J. Extracellular reduction of solid electron acceptors by Shewanella oneidensis. Mol Microbiol 2018; 109:571-583. [PMID: 29995975 DOI: 10.1111/mmi.14067] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2018] [Indexed: 12/11/2022]
Abstract
Shewanella oneidensis is the best understood model organism for the study of dissimilatory iron reduction. This review focuses on the current state of our knowledge regarding this extracellular respiratory process and highlights its physiologic, regulatory and biochemical requirements. It seems that we have widely understood how respiratory electrons can reach the cell surface and what the minimal set of electron transport proteins to the cell surface is. Nevertheless, even after decades of work in different research groups around the globe there are still several important questions that were not answered yet. In particular, the physiology of this organism, the possible evolutionary benefit of some responses to anoxic conditions, as well as the exact mechanism of electron transfer onto solid electron acceptors are yet to be addressed. The elucidation of these questions will be a great challenge for future work and important for the application of extracellular respiration in biotechnological processes.
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Affiliation(s)
- Sebastian Beblawy
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (CS), Karlsruhe, Germany
| | - Thea Bursac
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (CS), Karlsruhe, Germany
| | - Catarina Paquete
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Av. da República-EAN, Oeiras, 2780-157, Portugal
| | - Ricardo Louro
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Av. da República-EAN, Oeiras, 2780-157, Portugal
| | - Thomas A Clarke
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Johannes Gescher
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (CS), Karlsruhe, Germany.,Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
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17
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Shewanella oneidensis MR-1 Utilizes both Sodium- and Proton-Pumping NADH Dehydrogenases during Aerobic Growth. Appl Environ Microbiol 2018; 84:AEM.00415-18. [PMID: 29654176 PMCID: PMC5981069 DOI: 10.1128/aem.00415-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 04/05/2018] [Indexed: 02/02/2023] Open
Abstract
Shewanella oneidensis MR-1 is a metal-reducing bacterium with the ability to utilize many different terminal electron acceptors, including oxygen and solid-metal oxides. Both metal oxide reduction and aerobic respiration have been studied extensively in this organism. However, electron transport chain processes upstream of the terminal oxidoreductases have been relatively understudied in this organism, especially electron transfer from NADH to respiratory quinones. Genome annotation indicates that S. oneidensis MR-1 encodes four NADH dehydrogenases, a proton-translocating dehydrogenase (Nuo), two sodium ion-translocating dehydrogenases (Nqr1 and Nqr2), and an “uncoupling” dehydrogenase (Ndh), but none of these complexes have been studied. Therefore, we conducted a study specifically focused on the effects of individual NADH dehydrogenase knockouts in S. oneidensis MR-1. We observed that two of the single-mutant strains, the ΔnuoN and ΔnqrF1 mutants, exhibited significant growth defects compared with the wild type. However, the defects were minor and only apparent under certain growth conditions. Further testing of the ΔnuoN ΔnqrF1 double-mutant strain yielded no growth in minimal medium under oxic conditions, indicating that Nuo and Nqr1 have overlapping functions, but at least one is necessary for aerobic growth. Coutilization of proton- and sodium ion-dependent energetics has important implications for the growth of this organism in environments with varied pH and salinity, including microbial electrochemical systems. IMPORTANCE Bacteria utilize a wide variety of metabolic pathways that allow them to take advantage of different energy sources, and to do so with varied efficiency. The efficiency of a metabolic process determines the growth yield of an organism, or the amount of biomass it produces per amount of substrate consumed. This parameter has important implications in biotechnology and wastewater treatment, where low growth yields are often preferred to minimize the production of microbial biomass. In this study, we investigated respiratory pathways containing NADH dehydrogenases with varied efficiency (i.e., the number of ions translocated per NADH oxidized) in the metal-reducing bacterium Shewanella oneidensis MR-1. We observed that two different respiratory pathways are used concurrently, and at least one pathway must be functional for growth under oxic conditions.
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18
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Effect of the anode potential on the physiology and proteome of Shewanella oneidensis MR-1. Bioelectrochemistry 2018; 119:172-179. [DOI: 10.1016/j.bioelechem.2017.10.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Revised: 10/02/2017] [Accepted: 10/02/2017] [Indexed: 11/19/2022]
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19
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Metabolic Reconstruction and Modeling Microbial Electrosynthesis. Sci Rep 2017; 7:8391. [PMID: 28827682 PMCID: PMC5566340 DOI: 10.1038/s41598-017-08877-z] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 07/19/2017] [Indexed: 12/31/2022] Open
Abstract
Microbial electrosynthesis is a renewable energy and chemical production platform that relies on microbial cells to capture electrons from a cathode and fix carbon. Yet despite the promise of this technology, the metabolic capacity of the microbes that inhabit the electrode surface and catalyze electron transfer in these systems remains largely unknown. We assembled thirteen draft genomes from a microbial electrosynthesis system producing primarily acetate from carbon dioxide, and their transcriptional activity was mapped to genomes from cells on the electrode surface and in the supernatant. This allowed us to create a metabolic model of the predominant community members belonging to Acetobacterium, Sulfurospirillum, and Desulfovibrio. According to the model, the Acetobacterium was the primary carbon fixer, and a keystone member of the community. Transcripts of soluble hydrogenases and ferredoxins from Acetobacterium and hydrogenases, formate dehydrogenase, and cytochromes of Desulfovibrio were found in high abundance near the electrode surface. Cytochrome c oxidases of facultative members of the community were highly expressed in the supernatant despite completely sealed reactors and constant flushing with anaerobic gases. These molecular discoveries and metabolic modeling now serve as a foundation for future examination and development of electrosynthetic microbial communities.
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20
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Liu T, Wu Y, Li F, Li X, Luo X. Rapid Redox Processes ofc-Type Cytochromes in A Living Cell Suspension ofShewanella oneidensisMR-1. ChemistrySelect 2017. [DOI: 10.1002/slct.201602021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Tongxu Liu
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 PR China
| | - Yundang Wu
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 PR China
| | - Fangbai Li
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 PR China
| | - Xiaomin Li
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 PR China
| | - Xiaobo Luo
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 PR China
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21
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Modulation of the reactivity of multiheme cytochromes by site-directed mutagenesis: moving towards the optimization of microbial electrochemical technologies. J Biol Inorg Chem 2016; 22:87-97. [DOI: 10.1007/s00775-016-1409-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 10/21/2016] [Indexed: 01/06/2023]
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22
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Fowler GJS, Pereira-Medrano AG, Jaffe S, Pasternak G, Pham TK, Ledezma P, Hall STE, Ieropoulos IA, Wright PC. An iTRAQ characterisation of the role of TolC during electron transfer from Shewanella oneidensis MR-1. Proteomics 2016; 16:2764-2775. [PMID: 27599463 DOI: 10.1002/pmic.201500538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 07/20/2016] [Accepted: 09/02/2016] [Indexed: 02/04/2023]
Abstract
Anodophilic bacteria have the ability to generate electricity in microbial fuel cells (MFCs) by extracellular electron transfer to the anode. We investigated the anode-specific responses of Shewanella oneidensis MR-1, an exoelectroactive Gammaproteobacterium, using for the first time iTRAQ and 2D-LC MS/MS driven membrane proteomics to compare protein abundances in S. oneidensis when generating power in MFCs, and growing in a continuous culture. The regulated dataset produced was enriched in membrane proteins. Proteins shown to be more abundant in anaerobic electroactive anodic cells included efflux pump TolC and an uncharacterised tetratricopeptide repeat (TPR) protein, whilst the TonB2 system and associated uncharacterised proteins such as TtpC2 and DUF3450 were more abundant in microaerobic planktonic cells. In order to validate the iTRAQ data, the functional role for TolC was examined using a δTolC knockout mutant of S. oneidensis. Possible roles for the uncharacterised proteins were identified using comparative bioinformatics. We demonstrate that employing an insoluble extracellular electron acceptor requires multiple proteins involved in cell surface properties. All MS and processed data are available via ProteomeXchange with identifier PXD004090.
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Affiliation(s)
- Gregory J S Fowler
- Biological and Environmental Systems Group, ChELSI Institute, Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK
| | - Ana G Pereira-Medrano
- Biological and Environmental Systems Group, ChELSI Institute, Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK
| | - Stephen Jaffe
- Biological and Environmental Systems Group, ChELSI Institute, Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK
| | - Grzegorz Pasternak
- Bristol Robotics Laboratory, Universities of Bristol and of the West of England, , Frenchay Campus, Bristol, UK
| | - Trong Khoa Pham
- Biological and Environmental Systems Group, ChELSI Institute, Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK
| | - Pablo Ledezma
- Bristol Robotics Laboratory, Universities of Bristol and of the West of England, , Frenchay Campus, Bristol, UK
| | - Simon T E Hall
- Biological and Environmental Systems Group, ChELSI Institute, Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK
| | - Ioannis A Ieropoulos
- Bristol Robotics Laboratory, Universities of Bristol and of the West of England, , Frenchay Campus, Bristol, UK
| | - Phillip C Wright
- Biological and Environmental Systems Group, ChELSI Institute, Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK. .,Faculty of Science, Agriculture & Engineering, Newcastle University, Devonshire Building, Newcastle upon Tyne, UK.
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23
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Speers AM, Schindler BD, Hwang J, Genc A, Reguera G. Genetic Identification of a PilT Motor in Geobacter sulfurreducens Reveals a Role for Pilus Retraction in Extracellular Electron Transfer. Front Microbiol 2016; 7:1578. [PMID: 27799920 PMCID: PMC5065972 DOI: 10.3389/fmicb.2016.01578] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/21/2016] [Indexed: 12/13/2022] Open
Abstract
The metal-reducing bacterium Geobacter sulfurreducens requires the expression of conductive pili to reduce iron oxides and to wire electroactive biofilms, but the role of pilus retraction in these functions has remained elusive. Here we show that of the four PilT proteins encoded in the genome of G. sulfurreducens, PilT3 powered pilus retraction in planktonic cells of a PilT-deficient strain of P. aeruginosa and restored the dense mutant biofilms to wild-type levels. Furthermore, PilT3 and PilT4 rescued the twitching motility defect of the PilT-deficient mutant. However, PilT4 was the only paralog whose inactivation in G. sulfurreducens lead to phenotypes associated with the hyperpiliation of non-retractile mutants such as enhanced adhesion and biofilm-forming abilities. In addition, PilT4 was required to reduce iron oxides. Taken together, the results indicate that PilT4 is the motor ATPase of G. sulfurreducens pili and reveal a previously unrecognized role for pilus retraction in extracellular electron transfer, a strategy that confers on Geobacter spp. an adaptive advantage for metal reduction in the natural environment.
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Affiliation(s)
- Allison M Speers
- Department of Microbiology and Molecular Genetics, Michigan State University East Lansing, MI, USA
| | - Bryan D Schindler
- Department of Microbiology and Molecular Genetics, Michigan State University East Lansing, MI, USA
| | - Jihwan Hwang
- Department of Microbiology and Molecular Genetics, Michigan State University East Lansing, MI, USA
| | - Aycin Genc
- Department of Microbiology and Molecular Genetics, Michigan State University East Lansing, MI, USA
| | - Gemma Reguera
- Department of Microbiology and Molecular Genetics, Michigan State University East Lansing, MI, USA
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24
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Flavin as an Indicator of the Rate-Limiting Factor for Microbial Current Production in Shewanella oneidensis MR-1. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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25
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Lu M, Chan S, Babanova S, Bretschger O. Effect of oxygen on the per-cell extracellular electron transfer rate of Shewanella oneidensis MR-1 explored in bioelectrochemical systems. Biotechnol Bioeng 2016; 114:96-105. [PMID: 27399911 PMCID: PMC5132103 DOI: 10.1002/bit.26046] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 07/06/2016] [Indexed: 02/03/2023]
Abstract
Extracellular electron transfer (EET) is a mechanism that enables microbes to respire solid‐phase electron acceptors. These EET reactions most often occur in the absence of oxygen, since oxygen can act as a competitive electron acceptor for many facultative microbes. However, for Shewanella oneidensis MR‐1, oxygen may increase biomass development, which could result in an overall increase in EET activity. Here, we studied the effect of oxygen on S. oneidensis MR‐1 EET rates using bioelectrochemical systems (BESs). We utilized optically accessible BESs to monitor real‐time biomass growth, and studied the per‐cell EET rate as a function of oxygen and riboflavin concentrations in BESs of different design and operational conditions. Our results show that oxygen exposure promotes biomass development on the electrode, but significantly impairs per‐cell EET rates even though current production does not always decrease with oxygen exposure. Additionally, our results indicated that oxygen can affect the role of riboflavin in EET. Under anaerobic conditions, both current density and per‐cell EET rate increase with the riboflavin concentration. However, as the dissolved oxygen (DO) value increased to 0.42 mg/L, riboflavin showed very limited enhancement on per‐cell EET rate and current generation. Since it is known that oxygen can promote flavins secretion in S. oneidensis, the role of riboflavin may change under anaerobic and aerobic conditions. Biotechnol. Bioeng. 2017;114: 96–105. © 2016 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Mengqian Lu
- Department of Microbial and Environmental Genomics, J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, California 92037
| | - Shirley Chan
- Department of Microbial and Environmental Genomics, J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, California 92037
| | - Sofia Babanova
- Department of Microbial and Environmental Genomics, J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, California 92037.,Chemical and Biological Engineering, University of New Mexico, Albuquerque, New Mexico
| | - Orianna Bretschger
- Department of Microbial and Environmental Genomics, J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, California 92037
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Okamoto A, Tokunou Y, Saito J. Cation-limited kinetic model for microbial extracellular electron transport via an outer membrane cytochrome C complex. Biophys Physicobiol 2016; 13:71-76. [PMID: 27924259 PMCID: PMC5042175 DOI: 10.2142/biophysico.13.0_71] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 04/23/2016] [Indexed: 12/01/2022] Open
Abstract
Outer-membrane c-type cytochrome (OM c-Cyt) complexes in several genera of iron-reducing bacteria, such as Shewanella and Geobacter, are capable of transporting electrons from the cell interior to extracellular solids as a terminal step of anaerobic respiration. The kinetics of this electron transport has implications for controlling the rate of microbial electron transport during bioenergy or biochemical production, iron corrosion, and natural mineral cycling. Herein, we review the findings from in-vivo and in-vitro studies examining electron transport kinetics through single OM c-Cyt complexes in Shewanella oneidensis MR-1. In-vitro electron flux via a purified OM c-Cyt complex, comprised of MtrA, B, and C proteins from S. oneidensis MR-1, embedded in a proteoliposome system is reported to be 10- to 100-fold faster compared with in-vivo estimates based on measurements of electron flux per cell and OM c-Cyts density. As the proteoliposome system is estimated to have 10-fold higher cation flux via potassium channels than electrons, we speculate that the slower rate of electron-coupled cation transport across the OM is responsible for the significantly lower electron transport rate that is observed in-vivo. As most studies to date have primarily focused on the energetics or kinetics of interheme electron hopping in OM c-Cyts in this microbial electron transport mechanism, the proposed model involving cation transport provides new insight into the rate detemining step of EET, as well as the role of self-secreted flavin molecules bound to OM c-Cyt and proton management for energy conservation and production in S. oneidensis MR-1.
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Affiliation(s)
- Akihiro Okamoto
- Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan; Department of Applied Chemistry, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Yoshihide Tokunou
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Junki Saito
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
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Ding D, Li L, Shu C, Sun X. K-shell Analysis Reveals Distinct Functional Parts in an Electron Transfer Network and Its Implications for Extracellular Electron Transfer. Front Microbiol 2016; 7:530. [PMID: 27148219 PMCID: PMC4837345 DOI: 10.3389/fmicb.2016.00530] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 03/31/2016] [Indexed: 01/17/2023] Open
Abstract
Shewanella oneidensis MR-1 is capable of extracellular electron transfer (EET) and hence has attracted considerable attention. The EET pathways mainly consist of c-type cytochromes, along with some other proteins involved in electron transfer processes. By whole genome study and protein interactions inquisition, we constructed a large-scale electron transfer network containing 2276 interactions among 454 electron transfer related proteins in S. oneidensis MR-1. Using the k-shell decomposition method, we identified and analyzed distinct parts of the electron transfer network. We found that there was a negative correlation between the k s (k-shell values) and the average DR_100 (disordered regions per 100 amino acids) in every shell, which suggested that disordered regions of proteins played an important role during the formation and extension of the electron transfer network. Furthermore, proteins in the top three shells of the network are mainly located in the cytoplasm and inner membrane; these proteins can be responsible for transfer of electrons into the quinone pool in a wide variety of environmental conditions. In most of the other shells, proteins are broadly located throughout the five cellular compartments (cytoplasm, inner membrane, periplasm, outer membrane, and extracellular), which ensures the important EET ability of S. oneidensis MR-1. Specifically, the fourth shell was responsible for EET and the c-type cytochromes in the remaining shells of the electron transfer network were involved in aiding EET. Taken together, these results show that there are distinct functional parts in the electron transfer network of S. oneidensis MR-1, and the EET processes could achieve high efficiency through cooperation through such an electron transfer network.
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Affiliation(s)
- Dewu Ding
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast UniversityNanjing, China; Department of Mathematics and Computer Science, Chizhou CollegeChizhou, China
| | - Ling Li
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University Nanjing, China
| | - Chuanjun Shu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University Nanjing, China
| | - Xiao Sun
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University Nanjing, China
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Ross DE, Marshall CW, May HD, Norman RS. Comparative Genomic Analysis of Sulfurospirillum cavolei MES Reconstructed from the Metagenome of an Electrosynthetic Microbiome. PLoS One 2016; 11:e0151214. [PMID: 26983005 PMCID: PMC4794192 DOI: 10.1371/journal.pone.0151214] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 02/23/2016] [Indexed: 11/19/2022] Open
Abstract
Sulfurospirillum spp. play an important role in sulfur and nitrogen cycling, and contain metabolic versatility that enables reduction of a wide range of electron acceptors, including thiosulfate, tetrathionate, polysulfide, nitrate, and nitrite. Here we describe the assembly of a Sulfurospirillum genome obtained from the metagenome of an electrosynthetic microbiome. The ubiquity and persistence of this organism in microbial electrosynthesis systems suggest it plays an important role in reactor stability and performance. Understanding why this organism is present and elucidating its genetic repertoire provide a genomic and ecological foundation for future studies where Sulfurospirillum are found, especially in electrode-associated communities. Metabolic comparisons and in-depth analysis of unique genes revealed potential ecological niche-specific capabilities within the Sulfurospirillum genus. The functional similarities common to all genomes, i.e., core genome, and unique gene clusters found only in a single genome were identified. Based upon 16S rRNA gene phylogenetic analysis and average nucleotide identity, the Sulfurospirillum draft genome was found to be most closely related to Sulfurospirillum cavolei. Characterization of the draft genome described herein provides pathway-specific details of the metabolic significance of the newly described Sulfurospirillum cavolei MES and, importantly, yields insight to the ecology of the genus as a whole. Comparison of eleven sequenced Sulfurospirillum genomes revealed a total of 6246 gene clusters in the pan-genome. Of the total gene clusters, 18.5% were shared among all eleven genomes and 50% were unique to a single genome. While most Sulfurospirillum spp. reduce nitrate to ammonium, five of the eleven Sulfurospirillum strains encode for a nitrous oxide reductase (nos) cluster with an atypical nitrous-oxide reductase, suggesting a utility for this genus in reduction of the nitrous oxide, and as a potential sink for this potent greenhouse gas.
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Affiliation(s)
- Daniel E. Ross
- Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, United States of America
| | - Christopher W. Marshall
- Department of Microbiology & Immunology, Marine Biomedicine & Environmental Science Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Harold D. May
- Department of Microbiology & Immunology, Marine Biomedicine & Environmental Science Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - R. Sean Norman
- Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, United States of America
- * E-mail:
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Identification and Characterization of the Novel Subunit CcoM in the cbb3₃Cytochrome c Oxidase from Pseudomonas stutzeri ZoBell. mBio 2016; 7:e01921-15. [PMID: 26814183 PMCID: PMC4742706 DOI: 10.1128/mbio.01921-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cytochrome c oxidases (CcOs), members of the heme-copper containing oxidase (HCO) superfamily, are the terminal enzymes of aerobic respiratory chains. The cbb3-type cytochrome c oxidases (cbb3-CcO) form the C-family and have only the central catalytic subunit in common with the A- and B-family HCOs. In Pseudomonas stutzeri, two cbb3 operons are organized in a tandem repeat. The atomic structure of the first cbb3 isoform (Cbb3-1) was determined at 3.2 Å resolution in 2010 (S. Buschmann, E. Warkentin, H. Xie, J. D. Langer, U. Ermler, and H. Michel, Science 329:327–330, 2010, http://dx.doi.org/10.1126/science.1187303). Unexpectedly, the electron density map of Cbb3-1 revealed the presence of an additional transmembrane helix (TMH) which could not be assigned to any known protein. We now identified this TMH as the previously uncharacterized protein PstZoBell_05036, using a customized matrix-assisted laser desorption ionization (MALDI)–tandem mass spectrometry setup. The amino acid sequence matches the electron density of the unassigned TMH. Consequently, the protein was renamed CcoM. In order to identify the function of this new subunit in the cbb3 complex, we generated and analyzed a CcoM knockout strain. The results of the biochemical and biophysical characterization indicate that CcoM may be involved in CcO complex assembly or stabilization. In addition, we found that CcoM plays a role in anaerobic respiration, as the ΔCcoM strain displayed altered growth rates under anaerobic denitrifying conditions. The respiratory chain has recently moved into the focus for drug development against prokaryotic human pathogens, in particular, for multiresistant strains (P. Murima, J. D. McKinney, and K. Pethe, Chem Biol 21:1423–1432, 2014, http://dx.doi.org/10.1016/j.chembiol.2014.08.020). cbb3-CcO is an essential enzyme for many different pathogenic bacterial species, e.g., Helicobacter pylori, Vibrio cholerae, and Pseudomonas aeruginosa, and represents a promising drug target. In order to develop compounds targeting these proteins, a detailed understanding of the molecular architecture and function is required. Here we identified and characterized a novel subunit, CcoM, in the cbb3-CcO complex and thereby completed the crystal structure of the Cbb3 oxidase from Pseudomonas stutzeri, a bacterium closely related to the human pathogen Pseudomonas aeruginosa.
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Yang Y, Xiang Y, Xu M. From red to green: the propidium iodide-permeable membrane of Shewanella decolorationis S12 is repairable. Sci Rep 2015; 5:18583. [PMID: 26687136 PMCID: PMC4685271 DOI: 10.1038/srep18583] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 11/20/2015] [Indexed: 11/09/2022] Open
Abstract
Viability is a common issue of concern in almost all microbial processes. Fluorescence-based assays are extensively used in microbial viability assessment, especially for mixed-species samples or biofilms. Propidium iodide (PI) is the most frequently used fluorescence indicator for cell viability based on the membrane permeability. Our results showed that the accumulation of succinate from fumarate respiration could induce PI-permeability in Shewanella decolorationis biofilm cells. Confocal laser scanning microscope further showed that the PI-permeable membrane could be repaired in situ when the extracellular succinate was eliminated by switching fumarate respiration to electrode respiration. Simultaneously with the membrane repair, the electrode respiring capacity of the originally PI-permeable cells was recovered. Agar-colony counts suggested that a major portion of the repaired cells were viable but nonculturable (VBNC). The results evidenced that S. decolorationis S12 has the capacity to repair PI-permeable membranes which suggests a reevaluation of the fate and function of the PI-permeable bacteria and expanded our knowledge on the flexibility of bacterial survival status in harsh environments.
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Affiliation(s)
- Yonggang Yang
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China
| | - Yinbo Xiang
- State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China
| | - Meiying Xu
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China
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ElMekawy A, Srikanth S, Bajracharya S, Hegab HM, Nigam PS, Singh A, Mohan SV, Pant D. Food and agricultural wastes as substrates for bioelectrochemical system (BES): The synchronized recovery of sustainable energy and waste treatment. Food Res Int 2015. [DOI: 10.1016/j.foodres.2014.11.045] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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Schmitz S, Nies S, Wierckx N, Blank LM, Rosenbaum MA. Engineering mediator-based electroactivity in the obligate aerobic bacterium Pseudomonas putida KT2440. Front Microbiol 2015; 6:284. [PMID: 25914687 PMCID: PMC4392322 DOI: 10.3389/fmicb.2015.00284] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/22/2015] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas putida strains are being developed as microbial production hosts for production of a range of amphiphilic and hydrophobic biochemicals. P. putida's obligate aerobic growth thereby can be an economical and technical challenge because it requires constant rigorous aeration and often causes reactor foaming. Here, we engineered a strain of P. putida KT2440 that can produce phenazine redox-mediators from Pseudomonas aeruginosa to allow partial redox balancing with an electrode under oxygen-limited conditions. P. aeruginosa is known to employ its phenazine-type redox mediators for electron exchange with an anode in bioelectrochemical systems (BES). We transferred the seven core phenazine biosynthesis genes phzA-G and the two specific genes phzM and phzS required for pyocyanin synthesis from P. aeruginosa on two inducible plasmids into P. putida KT2440. The best clone, P. putida pPhz, produced 45 mg/L pyocyanin over 25 h of growth, which was visible as blue color formation and is comparable to the pyocyanin production of P. aeruginosa. This new strain was then characterized under different oxygen-limited conditions with electrochemical redox control and changes in central energy metabolism were evaluated in comparison to the unmodified P. putida KT2440. In the new strain, phenazine synthesis with supernatant concentrations up to 33 μg/mL correlated linearly with the ability to discharge electrons to an anode, whereby phenazine-1-carboxylic acid served as the dominating redox mediator. P. putida pPhz sustained strongly oxygen-limited metabolism for up to 2 weeks at up to 12 μA/cm(2) anodic current density. Together, this work lays a foundation for future oxygen-limited biocatalysis with P. putida strains.
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Affiliation(s)
- Simone Schmitz
- Aachen Biology and Biotechnology, Institute of Applied Microbiology, RWTH Aachen University Aachen, Germany
| | - Salome Nies
- Aachen Biology and Biotechnology, Institute of Applied Microbiology, RWTH Aachen University Aachen, Germany
| | - Nick Wierckx
- Aachen Biology and Biotechnology, Institute of Applied Microbiology, RWTH Aachen University Aachen, Germany
| | - Lars M Blank
- Aachen Biology and Biotechnology, Institute of Applied Microbiology, RWTH Aachen University Aachen, Germany
| | - Miriam A Rosenbaum
- Aachen Biology and Biotechnology, Institute of Applied Microbiology, RWTH Aachen University Aachen, Germany
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Kasai T, Kouzuma A, Nojiri H, Watanabe K. Transcriptional mechanisms for differential expression of outer membrane cytochrome genes omcA and mtrC in Shewanella oneidensis MR-1. BMC Microbiol 2015; 15:68. [PMID: 25886963 PMCID: PMC4417206 DOI: 10.1186/s12866-015-0406-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 03/11/2015] [Indexed: 11/17/2022] Open
Abstract
Background Shewanella oneidensis MR-1 is capable of reducing extracellular electron acceptors, such as metals and electrodes, through the Mtr respiratory pathway, which consists of the outer membrane cytochromes OmcA and MtrC and associated proteins MtrA and MtrB. These proteins are encoded in the mtr gene cluster (omcA-mtrCAB) in the MR-1 chromosome. Results Here, we investigated the transcriptional mechanisms for the mtr genes and demonstrated that omcA and mtrC are transcribed from two upstream promoters, PomcA and PmtrC, respectively. In vivo transcription and in vitro electrophoretic mobility shift assays revealed that a cAMP receptor protein (CRP) positively regulates the expression of the mtr genes by binding to the upstream regions of PomcA and PmtrC. However, the expression of omcA and mtrC was differentially regulated in response to culture conditions; specifically, the expression from PmtrC was higher under aerobic conditions than that under anaerobic conditions with fumarate as an electron acceptor, whereas expression from PomcA exhibited the opposite trend. Deletion of the region upstream of the CRP-binding site of PomcA resulted in a significant increase in promoter activity under aerobic conditions, demonstrating that the deleted region is involved in the negative regulation of PomcA. Conclusions Taken together, the present results indicate that transcription of the mtr genes is regulated by multiple promoters and regulatory systems, including the CRP/cAMP-dependent regulatory system and yet-unidentified negative regulators. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0406-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Takuya Kasai
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, 192-0392, Tokyo, Japan.
| | - Atsushi Kouzuma
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, 192-0392, Tokyo, Japan.
| | - Hideaki Nojiri
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, 113-8657, Tokyo, Japan.
| | - Kazuya Watanabe
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, 192-0392, Tokyo, Japan.
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Ma C, Yu Z, Lu Q, Zhuang L, Zhou SG. Anaerobic humus and Fe(III) reduction and electron transport pathway by a novel humus-reducing bacterium, Thauera humireducens SgZ-1. Appl Microbiol Biotechnol 2014; 99:3619-28. [PMID: 25503315 DOI: 10.1007/s00253-014-6254-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Accepted: 11/18/2014] [Indexed: 11/30/2022]
Abstract
In this study, an anaerobic batch experiment was conducted to investigate the humus- and Fe(III)-reducing ability of a novel humus-reducing bacterium, Thauera humireducens SgZ-1. Inhibition tests were also performed to explore the electron transport pathways with various electron acceptors. The results indicate that in anaerobic conditions, strain SgZ-1 possesses the ability to reduce a humus analog, humic acids, soluble Fe(III), and Fe(III) oxides. Acetate, propionate, lactate, and pyruvate were suitable electron donors for humus and Fe(III) reduction by strain SgZ-1, while fermentable sugars (glucose and sucrose) were not. UV-visible spectra obtained from intact cells of strain SgZ-1 showed absorption peaks at 420, 522, and 553 nm, characteristic of c-type cytochromes (cyt c). Dithionite-reduced cyt c was reoxidized by Fe-EDTA and HFO (hydrous ferric oxide), which suggests that cyt c within intact cells of strain SgZ-1 has the ability to donate electrons to extracellular Fe(III) species. Inhibition tests revealed that dehydrogenases, quinones, and cytochromes b/c (cyt b/c) were involved in reduction of AQS (9, 10-anthraquinone-2-sulfonic acid, humus analog) and oxygen. In contrast, only NADH dehydrogenase was linked to electron transport to HFO, while dehydrogenases and cyt b/c were found to participate in the reduction of Fe-EDTA. Thus, various different electron transport pathways are employed by strain SgZ-1 for different electron acceptors. The results from this study help in understanding the electron transport processes and environmental responses of the genus Thauera.
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Affiliation(s)
- Chen Ma
- Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, 510650, People's Republic of China
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Yin J, Jin M, Zhang H, Ju L, Zhang L, Gao H. Regulation of nitrite resistance of the cytochrome cbb3 oxidase by cytochrome c ScyA in Shewanella oneidensis. Microbiologyopen 2014; 4:84-99. [PMID: 25417822 PMCID: PMC4335978 DOI: 10.1002/mbo3.224] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/24/2014] [Accepted: 11/03/2014] [Indexed: 12/03/2022] Open
Abstract
Cytochrome c proteins, as enzymes to exchange electrons with substrates or as pure electron carriers to shuttle electrons, play vital roles in bacterial respiration and photosynthesis. In Shewanella oneidensis, a research model for the respiratory diversity, at least 42 c-type cytochromes are predicted to be encoded in the genome and are regarded to be the foundation of its highly branched electron transport pathways. However, only a small number of c-type cytochromes have been extensively studied. In this study, we identify soluble cytochrome c ScyA as an important factor influencing the nitrite resistance of a strain devoid of the bd oxidase by utilizing a newly developed transposon mutagenesis vector, which enables overexpression of the gene(s) downstream of the insertion site. We show that when in overabundance ScyA facilitates growth against nitrite inhibition by enhancing nitrite resistance of the cbb3 oxidase. Based on the data presented in this study, we suggest two possible mechanisms underlying the observed effect of ScyA: (1) ScyA increases electron flow to the cbb3 oxidase; (2) ScyA promotes nitrite resistance of the cbb3 oxidase, possibly by direct interaction.
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Affiliation(s)
- Jianhua Yin
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
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TerAvest MA, Rosenbaum MA, Kotloski NJ, Gralnick JA, Angenent LT. Oxygen allows Shewanella oneidensis MR-1 to overcome mediator washout in a continuously fed bioelectrochemical system. Biotechnol Bioeng 2014; 111:692-9. [PMID: 24122485 DOI: 10.1002/bit.25128] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 09/30/2013] [Accepted: 10/01/2013] [Indexed: 11/07/2022]
Abstract
Many bioelectrochemical systems (BESs) harness the ability of electrode-active microbes to catalyze reactions between electrodes and chemicals, often to perform useful functions such as wastewater treatment, fuel production, and biosensing. A microbial fuel cell (MFC) is one type of BES, which generates electric power through microbial respiration with an anode as the electron acceptor, and typically with oxygen reduction at the cathode to provide the terminal electron acceptor. Oxygen intrusion into MFCs is typically viewed as detrimental because it competes with anodes for electrons and lowers the coulombic efficiency. However, recent evidence suggests that it does not necessarily lead to lower performances—particularly for the model organism Shewanella oneidensis MR-1. Because flavin-mediated electron transfer is important for Shewanella species, which can produce this electron shuttle endogenuously, we investigated the role of flavins in the performance of pure-culture BESs with S. oneidensis MR-1 with and without oxygen. We found that oxygen increases current production more than twofold under continuously fed conditions, but only modestly increases current production under batch-fed conditions.We hypothesized that oxygen is more beneficial under continuously fed conditions because it allows S. oneidensis to grow and produce flavins at a faster rate, and thus lowers flavin washout. Our conclusions were supported by experiments with a flavin-secretion deficient mutant of S. oneidensis.
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cbb3-type cytochrome c oxidases, aerobic respiratory enzymes, impact the anaerobic life of Pseudomonas aeruginosa PAO1. J Bacteriol 2014; 196:3881-9. [PMID: 25182494 DOI: 10.1128/jb.01978-14] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
For bacteria, many studies have focused on the role of respiratory enzymes in energy conservation; however, their effect on cell behavior is poorly understood. Pseudomonas aeruginosa can perform both aerobic respiration and denitrification. Previous studies demonstrated that cbb3-type cytochrome c oxidases that support aerobic respiration are more highly expressed in P. aeruginosa under anoxic conditions than are other aerobic respiratory enzymes. However, little is known about their role under such conditions. In this study, it was shown that cbb3 oxidases of P. aeruginosa PAO1 alter anaerobic growth, the denitrification process, and cell morphology under anoxic conditions. Furthermore, biofilm formation was promoted by the cbb3 oxidases under anoxic conditions. cbb3 oxidases led to the accumulation of nitric oxide (NO), which is produced during denitrification. Cell elongation induced by NO accumulation was reported to be required for robust biofilm formation of P. aeruginosa PAO1 under anoxic conditions. Our data show that cbb3 oxidases promote cell elongation by inducing NO accumulation during the denitrification process, which further leads to robust biofilms. Our findings show that cbb3 oxidases, which have been well studied as aerobic respiratory enzymes, are also involved in denitrification and influence the lifestyle of P. aeruginosa PAO1 under anoxic conditions.
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38
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TerAvest MA, Angenent LT. Oxidizing Electrode Potentials Decrease Current Production and Coulombic Efficiency through Cytochrome cInactivation inShewanella oneidensisMR-1. ChemElectroChem 2014. [DOI: 10.1002/celc.201402128] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Yang Y, Xiang Y, Xia C, Wu WM, Sun G, Xu M. Physiological and electrochemical effects of different electron acceptors on bacterial anode respiration in bioelectrochemical systems. BIORESOURCE TECHNOLOGY 2014; 164:270-275. [PMID: 24862003 DOI: 10.1016/j.biortech.2014.04.098] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/23/2014] [Accepted: 04/25/2014] [Indexed: 06/03/2023]
Abstract
To understand the interactions between bacterial electrode respiration and the other ambient bacterial electron acceptor reductions, alternative electron acceptors (nitrate, Fe2O3, fumarate, azo dye MB17) were added singly or multiply into Shewanella decolorationis microbial fuel cells (MFCs). All the added electron acceptors were reduced simultaneously with current generation. Adding nitrate or MB17 resulted in more rapid cell growth, higher flavin concentration and higher biofilm metabolic viability, but lower columbic efficiency (CE) and normalized energy recovery (NER) while the CE and NER were enhanced by Fe2O3 or fumarate. The added electron acceptors also significantly influenced the cyclic voltammetry profile of anode biofilm probably via altering the cytochrome c expression. The highest power density was observed in MFCs added with MB17 due to the electron shuttle role of the naphthols from MB17 reduction. The results provided important information for MFCs applied in practical environments where contains various electron acceptors.
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Affiliation(s)
- Yonggang Yang
- State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China; Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, China
| | - Yinbo Xiang
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, China
| | - Chunyu Xia
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, China
| | - Wei-Min Wu
- Department of Civil & Environmental Engineering, Center for Sustainable Development & Global Competitiveness, Stanford University, Stanford 94305-4020, USA
| | - Guoping Sun
- State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China; Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, China
| | - Meiying Xu
- State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China; Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, China.
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Rimboud M, Pocaznoi D, Erable B, Bergel A. Electroanalysis of microbial anodes for bioelectrochemical systems: basics, progress and perspectives. Phys Chem Chem Phys 2014; 16:16349-66. [DOI: 10.1039/c4cp01698j] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Over about the last ten years, microbial anodes have been the subject of a huge number of fundamental studies dealing with an increasing variety of possible application domains.
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Affiliation(s)
- M. Rimboud
- Laboratoire de Génie Chimique
- CNRS - Université de Toulouse
- 31432 Toulouse, France
| | - D. Pocaznoi
- Laboratoire de Génie Chimique
- CNRS - Université de Toulouse
- 31432 Toulouse, France
| | - B. Erable
- Laboratoire de Génie Chimique
- CNRS - Université de Toulouse
- 31432 Toulouse, France
| | - A. Bergel
- Laboratoire de Génie Chimique
- CNRS - Université de Toulouse
- 31432 Toulouse, France
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Comparative c-type cytochrome expression analysis in Shewanella oneidensis strain MR-1 and Anaeromyxobacter dehalogenans strain 2CP-C grown with soluble and insoluble oxidized metal electron acceptors. Biochem Soc Trans 2013; 40:1204-10. [PMID: 23176455 DOI: 10.1042/bst20120182] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The genomes of Shewanella oneidensis strain MR-1 and Anaeromyxobacter dehalogenans strain 2CP-C encode 40 and 69 putative c-type cytochrome genes respectively. Deletion mutant and biochemical studies have assigned specific functions to a few c-type cytochromes involved in electron transfer to oxidized metals in S. oneidensis strain MR-1. Although promising, the genetic approach is limited to gene deletions that produce a distinct phenotype and to an organism for which a genetic system is available. To investigate and compare c-type cytochrome expression in S. oneidensis strain MR-1 and Anaeromyxobacter dehalogenans strain 2CP-C more comprehensively, proteomic measurements were used to characterize lysates of cells grown with soluble Fe(III) (as ferric citrate) and insoluble Mn(IV) (as MnO2) as electron acceptors. Strain MR-1 expressed 19 and 20, and strain 2CP-C expressed 27 and 25, c-type cytochromes when grown with Fe(III) and Mn(IV) respectively. The majority of c-type cytochromes (77% for strain MR-1 and 63% for strain 2CP-C) were expressed under both growth conditions; however, the analysis also revealed unique c-type cytochromes that were specifically expressed in cells grown with soluble Fe(III) or insoluble Mn(IV). Proteomic characterization proved to be a promising approach for determining the c-type cytochrome complement expressed under different growth conditions, and will help to elucidate the specific functions of more c-type cytochromes that are the basis for Shewanella and Anaeromyxobacter respiratory versatility.
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Mind the gap: cytochrome interactions reveal electron pathways across the periplasm of Shewanella oneidensis MR-1. Biochem J 2012; 449:101-8. [DOI: 10.1042/bj20121467] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Extracellular electron transfer is the key metabolic trait that enables some bacteria to play a significant role in the biogeochemical cycling of metals and in bioelectrochemical devices such as microbial fuel cells. In Shewanella oneidensis MR-1, electrons generated in the cytoplasm by catabolic processes must cross the periplasmic space to reach terminal oxidoreductases found at the cell surface. Lack of knowledge on how these electrons flow across the periplasmic space is one of the unresolved issues related with extracellular electron transfer. Using NMR to probe protein–protein interactions, kinetic measurements of electron transfer and electrostatic calculations, we were able to identify protein partners and their docking sites, and determine the dissociation constants. The results showed that both STC (small tetrahaem cytochrome c) and FccA (flavocytochrome c) interact with their redox partners, CymA and MtrA, through a single haem, avoiding the establishment of stable redox complexes capable of spanning the periplasmic space. Furthermore, we verified that the most abundant periplasmic cytochromes STC, FccA and ScyA (monohaem cytochrome c5) do not interact with each other and this is likely to be the consequence of negative surface charges in these proteins. This reveals the co-existence of two non-mixing redox pathways that lead to extracellular electron transfer in S. oneidensis MR-1 established through transient protein interactions.
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Transcriptome analysis of early surface-associated growth of Shewanella oneidensis MR-1. PLoS One 2012; 7:e42160. [PMID: 22860070 PMCID: PMC3409153 DOI: 10.1371/journal.pone.0042160] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 07/02/2012] [Indexed: 11/30/2022] Open
Abstract
Bacterial biofilm formation starts with single cells attaching to a surface, however, little is known about the initial attachment steps and the adaptation to the surface-associated life style. Here, we describe a hydrodynamic system that allows easy harvest of cells at very early biofilm stages. Using the metal ion-reducing gammaproteobacterium Shewanella oneidensis MR-1 as a model organism, we analyzed the transcriptional changes occurring during surface-associated growth between 15 and 60 minutes after attachment. 230 genes were significantly upregulated and 333 were downregulated by a factor of ≥2. Main functional categories of the corresponding gene products comprise metabolism, uptake and transport, regulation, and hypothetical proteins. Among the genes highly upregulated those implicated in iron uptake are highly overrepresented, strongly indicating that S. oneidensis MR-1 has a high demand for iron during surface attachment and initial biofilm stages. Subsequent microscopic analysis of biofilm formation under hydrodynamic conditions revealed that addition of Fe(II) significantly stimulated biofilm formation of S. oneidensis MR-1 while planktonic growth was not affected. Our approach to harvest cells for transcriptional analysis of early biofilm stages is expected to be easily adapted to other bacterial species.
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Marritt SJ, Lowe TG, Bye J, McMillan DGG, Shi L, Fredrickson J, Zachara J, Richardson DJ, Cheesman MR, Jeuken LJC, Butt JN. A functional description of CymA, an electron-transfer hub supporting anaerobic respiratory flexibility in Shewanella. Biochem J 2012; 444:465-74. [PMID: 22458729 DOI: 10.1042/bj20120197] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
CymA (tetrahaem cytochrome c) is a member of the NapC/NirT family of quinol dehydrogenases. Essential for the anaerobic respiratory flexibility of shewanellae, CymA transfers electrons from menaquinol to various dedicated systems for the reduction of terminal electron acceptors including fumarate and insoluble minerals of Fe(III). Spectroscopic characterization of CymA from Shewanella oneidensis strain MR-1 identifies three low-spin His/His co-ordinated c-haems and a single high-spin c-haem with His/H(2)O co-ordination lying adjacent to the quinol-binding site. At pH 7, binding of the menaquinol analogue, 2-heptyl-4-hydroxyquinoline-N-oxide, does not alter the mid-point potentials of the high-spin (approximately -240 mV) and low-spin (approximately -110, -190 and -265 mV) haems that appear biased to transfer electrons from the high- to low-spin centres following quinol oxidation. CymA is reduced with menadiol (E(m) = -80 mV) in the presence of NADH (E(m) = -320 mV) and an NADH-menadione (2-methyl-1,4-naphthoquinone) oxidoreductase, but not by menadiol alone. In cytoplasmic membranes reduction of CymA may then require the thermodynamic driving force from NADH, formate or H2 oxidation as the redox poise of the menaquinol pool in isolation is insufficient. Spectroscopic studies suggest that CymA requires a non-haem co-factor for quinol oxidation and that the reduced enzyme forms a 1:1 complex with its redox partner Fcc3 (flavocytochrome c3 fumarate reductase). The implications for CymA supporting the respiratory flexibility of shewanellae are discussed.
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Affiliation(s)
- Sophie J Marritt
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, U.K
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