Long-distance electron transport by cable bacteria in mangrove sediments

Cable bacteria are long, filamentoussulphur-oxidizing bacteria that induce long-distanceelectron transport in aquatic sediments. They turnthe seafloor into an electro-active environment, characterizedby currents and electrical fields, and whenpresent, they exert a strong impact on the geochemicalcycling in the seafloor. However, cable bacteriahave only recently been discovered, and so their geographicaldistribution and habitat distribution remainlargely unknown. Here we report field evidence thatcable bacteria are present and active in mangrovesediments. Combining microsensor profiling andfluorescence in situ hybridization, we recorded highfilament densities (77 m cm-2) and the signature ofelectrogenic sulphur oxidation in sediments of greymangroves near Melbourne, Australia. Our findingssuggest that cable bacteria could be a keystonemicrobial species in the geochemical cycling ofmangroves