Check out the paper in Nature here. From the abstract,
Oxygen consumption in marine sediments is often coupled to the oxidation of sulphide generated by degradation of organic matter in deeper, oxygen-free layers. Geochemical observations have shown that this coupling can be mediated by electric currents carried by unidentified electron transporters across centimetre-wide zones. Here we present evidence that the native conductors are long, filamentous bacteria. They abounded in sediment zones with electric currents and along their length they contained strings with distinct properties in accordance with a function as electron transporters. Living, electrical cables add a new dimension to the understanding of interactions in nature and may find use in technology development.
Science Daily reports,
Researchers at Aarhus University, Denmark, made a sensational discovery almost three years ago when they measured electric currents in the seabed. It was unclear as to what was conducting the current, but the researchers imagined the electric currents might run between different bacteria via a joint external wiring network.The researchers have now solved the mystery. It turns out that the whole process takes place inside bacteria that are one centimetre long. They make up a kind of live electric cable that no one had ever imagined existed.
Each one of these ‘cable bacteria’ contains a bundle of insulated wires that conduct an electric current from one end to the other.