Figure 2.

Schematic Diagram of Interspecies Electron Transfer between Electron-Donating Bacteria (Blue) and Electron-Accepting Methanogens (Red)

DIET mechanisms: cell-to-cell electron transfer through electrically conductive pili (e-pili) (A), cell-to-cell electron transfer through cytochromes associated with outer cell surfaces (B), and cell-to-cell electron transfer through a conductive material (C). In contrast, cell-to-cell electron transfer via intermediary soluble electron carriers, like H₂, is a diffusive transport process (D).