Evidence of bacteria acting like electric cables is presented in Nature this week. Filamentous Deltaproteobacteria are shown to mediate electron transfer over centimetre distances in marine sediments. This capability allows them to exploit a major energy source in the sea floor.

Oxygen is only available in the uppermost layer of the marine sediments, and microorganisms living further below have to rely on energetically less-favourable anaerobic processes. Nils Risgaard-Petersen and colleagues have previously shown that the two environments are linked by an electric current that couples oxygen consumption at the surface to a biochemical reaction that oxidizes sulphur, a source of energy, below the surface. In their latest study, they find that filamentous bacteria are responsible for carrying these electric currents, providing them with a means of obtaining energy by connecting the oxygen reservoir at the sediment surface with hydrogen sulphide deep below.