Long distance microbial interspecies electron transfer in eutrophicated coastal marine sediment

自然环境下的生物地球化学元素循环是由一系列氧化还原过程组成的。空间分离(毫米到厘米尺度)的氧化和还原反应可以通过自然界中的电流耦合的概念现在得到了广泛的支持，但仍然没有确凿的证据在现场条件下证实这一点。我们研制了一种新型的微传感器，可以测量微米级和微伏级的电位，并在东京湾的沉积物表面获得了显著的现场正电位显微剖面图。东京湾沉积物中电子的长距离转移可能有两种机制，一种是导电矿物纳米颗粒(磁铁矿)，另一种是导电丝状细菌(脱硫球菌科)。磁铁矿可以通过结构Fe2+和Fe3+的固态循环传递电子。丝状细菌含有根据电子转运体的功能具有不同性质的串。

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.