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Wired Microbe Conducts Electricity

Shewanella proteins could be used to generate energy or immobilize contaminants

Shewanella oneidensis uses an electron-shuttling conduit made up of proteins to live off of metal in minerals such as this hematite.

A team of researchers from the University of East Anglia and Pacific Northwest National Laboratory have determined, for the first time, the molecular structure of the proteins that enable the bacterium Shewanella oneidensis to transfer an electrical charge. The bacteria survive in oxygen-free environments by constructing small wires that extend through the cell wall and contact minerals—a process called iron respiration or “breathing rocks.” Proteins within these wires pass electrons outward to create an electrical charge. Using X-ray crystallography at EMSL as part of the Biogeochemistry Grand Challenge, the scientists gained new insights about how these proteins work together to move electrons from the inside to the outside of a cell. Identifying the molecular structure of these proteins is a key step toward potentially using microbes as a source of electricity; for example, by connecting them to electrodes to create microbial fuel cells.  Because the bacteria also trap and transform the minerals they contact, the new information could advance the development of microbe-based agents for use in environmental remediation such as cleaning up legacy radioactive waste. 

For more information, read the press release(Offsite link) from the University of East Anglia.

Reference: Clarke TA, MJ Edwards, AJ Gates, A Hall, GF White, J Bradley, C Reardon, L Shi, AS Beliaev, MJ Marshall, Z Wang, NJ Watmough, J Fredrickson, J Zachara, JN Butt, and DJ Richardson. 2011. “Structure of a Bacterial Cell Surface Decaheme Electron Conduit.” Proc Natl Acad Sci USA, DOI 10.1073/pnas.1017200108.

Acknowledgement:  This work was supported by the Biotechnology and Biological Sciences Research Council, the EMSL Biogeochemistry Scientific Grand Challenge project, and the U.S. Department of Energy.

Released: June 10, 2011