Electric microbes at the bottom of the sea

At the bottom of the ocean lie vast reserves of methane, released by microbes feeding on the remains of dead algae and animals as they sink down from the surface. If the methane escaped into the atmosphere the gas would exacerbate global warming, but luckily a consortium of microbes seem to keep it in check.

The microscope revealed thin wire-like structures protruding from the bacterial cells. Although only a few nanometres wide, the wires were several micrometres long, which is much longer than the cells themselves. It seems that the bacteria use these nanowires to hook up with the archaea.

The archaea feed on electrons from methane, oxidising the gas to generate carbonate. They then pass the electrons on to their partner bacteria along the nanowires, which act like power cables. Finally the bacteria deposit the electrons onto sulphate, producing energy that the cell can use in the process.

In a more extreme version of this process, some bacteria can link up to form long "cables". Cable bacteria live on sea floors and river beds where there is little oxygen. Without oxygen, they have nowhere to donate their electrons. To cope with this the cable bacteria, which belong to the family Desulfobulbaceae, form chains, one cell in diameter, extending thousands of cells and distances of several centimetres – a huge distance for a bacterium only 3 or 4 micrometres long – until they finally reach a habitat with oxygen.

http://www.bbc.com/earth/story/20160613-there-are-microbes-that-eat-and-poo-nothing-but-electricity