Japanese researchers have developed biological fuel cells based on metal-reducing bacteria that aggregate into an electrically conducting network.

They investigated how this transfer is carried out in Shewanella loihica. They added the cells to a solution containing very finely divided nanoscopic iron oxide particles and poured the solution into a chamber containing electrodes. A layer of bacteria and iron oxide particles was rapidly deposited onto the indium tin oxide electrodes at the bottom of the chamber. When the cells were “fed” lactate, a current was detected. Electrons from the metabolism of the lactate are thus transferred from the bacteria to the electrode.