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Phys Chem Chem Phys. 2012 Oct 28;14(40):13802-8. Epub 2012 Jul 13.

Multistep hopping and extracellular charge transfer in microbial redox chains.

Author information

1
Department of Physics and Astronomy, University of Southern California, 920 Bloom Walk, Seaver Science Center 215C, Los Angeles, CA 90089-0484, USA.

Abstract

Dissimilatory metal-reducing bacteria are microorganisms that gain energy by transferring respiratory electrons to extracellular solid-phase electron acceptors. In addition to its importance for physiology and natural environmental processes, this form of metabolism is being investigated for energy conversion and fuel production in bioelectrochemical systems, where microbes are used as biocatalysts at electrodes. One proposed strategy to accomplish this extracellular charge transfer involves forming a conductive pathway to electrodes by incorporating redox components on outer cell membranes and along extracellular appendages known as microbial nanowires within biofilms. To describe extracellular charge transfer in microbial redox chains, we employed a model based on incoherent hopping between sites in the chain and an interfacial treatment of electrochemical interactions with the surrounding electrodes. Based on this model, we calculated the current-voltage (I-V) characteristics and found the results to be in good agreement with I-V measurements across and along individual microbial nanowires produced by the bacterium Shewanella oneidensis MR-1. Based on our analysis, we propose that multistep hopping in redox chains constitutes a viable strategy for extracellular charge transfer in microbial biofilms.

PMID:
22797729
DOI:
10.1039/c2cp41185g
[Indexed for MEDLINE]

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