Figure 6

A schematic of the anodic mechanisms in MFCs. (i) DET, the electron transfer involving c-type cytochrome. (ii) MET, the electron transfer driven by a mediator used process; red, reduced form; ox, oxidized form. Microbes take up substrate generating carbon dioxide and protons. This process yield electrons for metabolic benefit, i.e., growth, and reduce Med_ox in the cytosol into Medred. Med_red diffuse into contact with the electrode, where Med_red reduce the electrode generating electrical current. The oxidized form, Med_ox, diffuses back through anolyte for reuse by the microbes. Periplasm (only exist in gram-negative bacteria such as G. sulfurreducens).