Multiheme cytochrome mediated redox conduction through Shewanella oneidensis MR-1 cells

S. Xu, A. Barrozo, L.M. Tender, A.I. Krylov, and M.Y. El-Naggar
J. Am. Chem. Soc.  140, 10085 – 10089 (2018)

Multiheme cytochromes function as extra-cellular 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.

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