Bacteria made to sprout conducting nanowires

The discovery that a wide variety of bacteria can be persuaded to produce wire-like appendages that conduct electricity could prove vital to the development of more efficient biological fuel cells.

Bacteria that use sugars and sewage as fuel are being investigated as a pollution-free source of electricity. They feed by plucking electrons from atoms in their fuel and dumping them onto the oxygen or metal atoms in the mixture. The transfer of the electrons creates a current, and connecting the bacteria to an electrode in a microbial fuel cell will generate electricity, although not necessarily very efficiently.

A species of bacterium called Geobacter sulfurreducens, which dumps electrons onto metal, has previously been persuaded to grow nanowires to make contact with distant atoms (see Subterranean bugs reach out for their energy). A deficit of metal atoms in the close vicinity of the bacteria can cause a bottleneck, so the proliferation of nanowires allows the bacteria to consume more fuel, potentially boosting the current produced by a microbial fuel cell.

Now a study by Yuri Gorby of Pacific Northwest National Laboratories in Washington State, US, and colleagues reveals that several other kinds of bacteria produce similar nanowires.

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