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Published May 4, 2000 | public
Journal Article

A role for excreted quinones in extracellular electron transfer

Abstract

Respiratory processes in bacteria are remarkable because of their ability to use a variety of compounds, including insoluble minerals, as terminal electron acceptors. Although much is known about microbial electron transport to soluble electron acceptors, little is understood about electron transport to insoluble compounds such as ferric oxides. In anaerobic environments, humic substances can serve as electron acceptors and also as electron shuttles to ferric oxides. To explore this process, we identified mutants in Shewanella putrefaciens that are unable to respire on humic substances. Here we show that these mutants contain disruptions in a gene that is involved in the biosynthesis of menaquinone. During growth, the wild type releases a menaquinone-related redox-active small molecule into the medium that complements the mutants. This finding raises the possibility that electron transfer to a variety of oxidants, including poorly soluble minerals, may be mediated by microbially excreted quinones that have yet to be identified.

Additional Information

© 2000 Macmillan Magazines Ltd. Received 14 December 1999; accepted 10 February 2000. We thank C. Myers for providing S. putrefaciens strain MR-1 and members of the Kolter lab, P. Belshaw, F. Morel, B. Schink and D. Lovley for advice and encouragement. Preliminary sequence data was obtained from The Institute for Genomic Research website (http://www.tigr.org). Sequencing of S. putrefaciens was accomplished with support from the Department of Energy. This research was supported by the Office of Naval Research, NIH and a postdoctoral fellowship to D.K.N. by the Cancer Research Fund of the Damon Runyon Walter Winchell Foundation.

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023