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Distance-Dependent Electron Transfer to Mineral Surfaces Mediated by Bacterial Multiheme Cytochromes


EMSL Project ID
24815

Abstract

The dissimilatory metal reducing bacterium Shewanella oneidensis is capable of utilizing certain mineral surfaces as electron acceptors in the terminal step of its respiratory pathway. Bacterial-mediated reductive dissolution of such minerals controls the solubility of not only the mineral phase, but of adsorbed species including various contaminants (e.g. uranium, arsenic) as well. Although specific mechanistic details of how S. oneidensis reduces mineral surfaces are not complete, it is well known that specific redox-active proteins called cytochromes are crucial to its reduction strategy by acting as metal-reducing enzymes.1 One specific question that still lingers, however, is what are the physical constraints that influence interfacial electron transfer between multiheme cytochromes and an oxide surface? This proposal outlines our plans to study such constraints (e.g. separation distance between cytochromes and the mineral surface, the electronic double layer at the mineral surface) as part of our team's continuing collaborative efforts to understand in molecular detail the nanoscale space occurring at the mineral-microbe interface2 and the geochemical processes that these interactions affect. By elucidating the molecular interfacial mechanisms of such a dynamic interface, we will gain a greater understanding of not only fundamental electron transfer reactions, but how they contribute to environmental systems.

This General Access proposal is submitted under the scientific call under the Geochemistry/Biogeochemistry and Subsurface Science Theme. The proposal is for Open-Access and is non-proprietary.

Project Details

Project type
Large-Scale EMSL Research
Start Date
2007-05-24
End Date
2009-09-30
Status
Closed

Team

Principal Investigator

Michael Hochella
Institution
Pacific Northwest National Laboratory

Team Members

Nicholas Wigginton
Institution
Virginia Polytechnic Institute

Kevin Rosso
Institution
Pacific Northwest National Laboratory

Related Publications

Wigginton N.S., Rosso K.M., Stack A.G., and Rosso K.M. (2009) Long-range electron transfer across cytochrome-hematite interfaces. J. Phys. Chem. C., 113(6), 2096-2103.