Bacterial nanowires (also known as microbial nanowires) are electrically conductive appendages produced by a number of bacteria most notably from (but not exclusive to) the Geobacter and Shewanella genera. Conductive nanowires have also been confirmed in the oxygenic cyanobacterium Synechocystis PCC6803 and a thermophilic, methanogenic coculture consisting of Pelotomaculum thermopropionicum and Methanothermobacter thermoautotrophicus.
Nanowires are modified pili, which are used to establish connections to terminal electron acceptors. Species of the genus Geobacter use nanowires to transfer electrons to extracellular electrical acceptors (such as Fe(III) oxides). This function was discovered through the examination of mutants, whose pili could attach to the iron, but would not reduce it. Additionally, nanowires can facilitate long-range electron transfer across thick biofilm layers. By connecting to other cells above them, pili allow bacteria located in anoxic conditions to still use oxygen as their terminal electron acceptor. For example, organisms in the genus Shewanella have been observed to form electrically conductive pili in response to electron-acceptor limitation.
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Implications and Potential Applications
Biologically it is unclear what is implied by the existence of bacterial nanowires.
- G. Reguera et al., Nature 435, 1098 (2005)
- Y. A. Gorby et al., Proceedings of the National Academy of Sciences of the United States of America 103, 11358 (2006).
- Reguera et al. 2005. Extracellular electron transfer via microbial nanowires. Nature 435:1098-1101 .
- Reguera et al. 2006. Biofilm and nanowire production leads to increased current in Geobacter sulfurreducens fuel cells. Appl. Environ. Microbiol. 72:7345-8.
- Gorby et al. 2006. Electrically conductive bacterial nanowires produced by Shewanella oneidensis strain MR-1 and other microorganisms. Proc Natl Acad Sci USA 103(30):11358-63.
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