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B.S., University of Washington, Seattle, WA, 2005
Honors and Awards:
Shewanella oneidensis is a member of the dissimilatory metal-reducing bacteria, which comprise a diverse group of microorganisms that cycle organic and inorganic compounds in many environments. S. oneidensis is a highly versatile organism that can respire numerous terminal electron acceptors, including insoluble extracellular minerals such as iron and manganese oxides. Due to this capacity for extracellular respiration, Shewanella is widely studied for potential uses in biotechnology and bioremediation, such as microbial fuel cells and toxic heavy metal sequestration. The respiration of ferric (Fe3+) oxide minerals by Shewanella results in the release of soluble ferrous (Fe2+) ions, which can then be taken up by the cells. However, high levels of Fe2+ are toxic to organisms, and therefore bacteria living in iron-rich environments have evolved ways to maintain optimal intracellular Fe2+ levels. My thesis involves understanding the ways in which S. oneidensis resists Fe2+ toxicity. One Fe2+ resistance mechanism that we have discovered S. oneidensis employs is an inner-membrane Fe2+ antiporter that we named FeoE, which utilizes proton motive force to export Fe2+ ions from the cytoplasm. The ATP-dependent protease ClpXP also appears to be important for resistance to Fe2+ toxicity. Our current work aims to understand which proteins are targeted for degradation by ClpXP under high Fe2+ concentrations, which will reveal why ClpXP is needed for Fe2+ resistance and may illuminate the mechanism by which Fe2+ is toxic anaerobically.
Bennett, B.D., Brutinel, E.D., and Gralnick, J.A. 2015. A ferrous iron exporter mediates iron resistance in Shewanella oneidensis MR-1. Appl Environ Microbiol. 15;81(22):7938-44.