Oram, J and Jeuken, LJC orcid.org/0000-0001-7810-3964 (2019) Tactic Response of Shewanella oneidensis MR-1 toward Insoluble Electron Acceptors. mBio, 10 (1). e02490-18. ISSN 2150-7511
Abstract
Exoelectrogenic bacteria are defined by their ability to respire on extracellular and insoluble electron acceptors and have applications in bioremediation and microbial electrochemical systems (MESs), while playing important roles in biogeochemical cycling. Shewanella oneidensis MR-1, which has become a model organism for the study of extracellular respiration, is known to display taxis toward insoluble electron acceptors, including electrodes. Multiple mechanisms have been proposed for MR-1’s tactic behavior, and, here, we report on the role of electrochemical potential by video microscopy cell tracking experiments in three-electrode electrochemical cells. MR-1 trajectories were determined using a particle tracking algorithm and validated with Shannon’s entropy method. Tactic response by MR-1 in the electrochemical cell was observed to depend on the applied potential, as indicated by the average velocity and density of motile (>4 µm/s) MR-1 close to the electrode (<50 µm). Tactic behavior was observed at oxidative potentials, with a strong switch between the potentials −0.15 to −0.25 V versus the standard hydrogen electrode (SHE), which coincides with the reduction potential of flavins. The average velocity and density of motile MR-1 close to the electrode increased when riboflavin was added (2 µM), but were completely absent in a ΔmtrC/ΔomcA mutant of MR-1. Besides flavin’s function as an electron mediator to support anaerobic respiration on insoluble electron acceptors, we propose that riboflavin is excreted by MR-1 to sense redox gradients in its environment, aiding taxis toward insoluble electron acceptors, including electrodes in MESs.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 Oram and Jeuken. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. |
Keywords: | Shewanella oneidensis; extracellular electron transfer; flavin; insoluble electron acceptors; microbe-mineral interactions; motility; respiration; taxis; tracking microscopy |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) > School of Biomedical Sciences (Leeds) |
Funding Information: | Funder Grant number BBSRC BB/L020130/1 EU - European Union 280518 |
Depositing User: | Symplectic Publications |
Date Deposited: | 07 Dec 2018 14:15 |
Last Modified: | 25 Jun 2023 21:37 |
Status: | Published |
Publisher: | American Society for Microbiology |
Identification Number: | 10.1128/mBio.02490-18 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:139645 |