In 2010, a completely novel type of microbial metabolism was discovered in marine sediments, which induces the transport of electrons over centimetre scales. The actors behind this process are the “cable bacteria”: long (> 2cm), filamentous, multicellular(>104 cells) bacteria. Cable bacteria use the electron transport to couple redox reactions between their two key metabolic resources. The bottom cells of a cable bacteria filament oxidize sulfide, which is abundant in the deeper anoxic zone of the marine sediment. The electrons derived from the sulfide oxidation are then transported along the cells of the cable bacteria to finally arrive at the cells in the oxic part of the sediment. Here these electrons are used in the second part of the cable bacteria metabolism, the reduction of oxygen. By establishing electrical currents, the cable bacteria turn the seafloor into an “electrical ecosystem”
