I came across this on the Pacific Northwest National Laboratory website about biofuel cells that don't really need much in the way of bio... It seems that some bacteria rely on proteins to distribute electricity on their surfaces as a way of dealing with excess energy they produce during metabolism.
Now, scientists for the first time have observed this electricity-shuttling process taking place sans cells, in purified proteins removed from the outer membrane of the versatile, metal-altering soil bacterium Shewanella oneidensis. Reporting in the current advance online edition of the Journal of the American Chemical Society, they suggest that proteins rendered portable from the organisms that spawned them could make miniature bioreactor cells feasible.
"We show that you can directly transfer electrons to a mineral using a purified protein, and I don't think anyone had shown that before," said Thomas Squier, senior author and lab fellow at the Department of Energy's Pacific Northwest National Laboratory.
The feat is the bacterial equivalent of removing lungs and coaxing the disembodied tissue to breathe.
Put that way it sounds quite revolting... but useful.