Long distance microbial interspecies electron transfer in eutrophicated coastal marine sediment

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Biogeochemical element cycling under natural environments consists cascades of oxidation-reduction processes. The concept that spatially segregated (mm to cm scale) oxidation&-reduction reactions can be coupled by electric currents in nature are now to be widely supported, but still no firm evidence exist to verify it under in situ conditions. We have developed a novel microsensor that is able to measure electric potential (EP) at micrometer and microvolt scales, and got significant positive in situ EP-microporfiles at the sediment surface in Tokyo Bay. There may be two mechanisms contributing for the long distance electron transfer in Tokyo Bay sediment, one is conductive mineral nanoparticles (magnetite) and the other is conductive filamentous bacteria (Desulfobulbaceae). Magnetite can transfer electrons through solid state cycling of structural Fe2+ and Fe3+. The filamentous bacteria contain strings with distinct properties in accordance with a function as electron transporters.