[Intercellular electron transfer and its eco-physiological significance: A review]

Intercellular electron transfer (IET) refers to the process within which electrons being indirectly or directly transferred to the exterior of cells and eventually delivered to the electron acceptors around cells. IET widely exists in nature, especially when electron acceptor are deficient. IET can be divided into two categories: indirect IET and direct IET. Indirect IET (intercellular substrate transfer) always occurs with electron transfer of hydrogen, formate, and other metabolites. Direct intracellular electron transfer is achieved by the coupling of intracellular and extracellular electron transfer. IET boosts the activity of cellular substrate metabolism and expands the acting space of cells. Moreover, IET generates electric current which provides driving-power for energy sharing between bacteria and transformation of extracellular material (such as heavy metals and humus). There is no doubt that IET has physiological and ecological significance. This review summarized recent advances, making a systematic analysis of the process, characteristics, mechanism and eco-physiological significance of IET.