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Multiheme Cytochrome Mediated Redox Conduction through Shewanella oneidensis MR‑1 Cells

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journal contribution
posted on 30.07.2018, 00:00 by Shuai Xu, Alexandre Barrozo, Leonard M. Tender, Anna I. Krylov, Mohamed Y. El-Naggar
Multiheme cytochromes function as extracellular electron transfer (EET) conduits that extend the metabolic reach of microorganisms to external solid surfaces. These conduits are also proposed to facilitate long-distance electron transport along cellular membranes and across multiple cells. Here we report electrochemical gating measurements of Shewanella oneidensis MR-1 cells linking interdigitated electrodes. The dependence of the source–drain current on gate potential demonstrates a redox conduction mechanism, which we link to the presence of multiheme cytochromes of the Mtr pathway. We also find that the measured thermal activation energy of 0.29 ± 0.03 eV is consistent with these obtained from electron hopping calculations through the S. oneidensis Mtr outer-membrane decaheme cytochromes. Our measurements and calculations have implications for understanding and controlling micrometer-scale electron transport in microbial systems.