FIGURE 2.

Examples of mechanisms of electron transfer. H₂ transfer between P. carbinolicus and G. sulfurreducens (A), bDIET between G. metallireducens and G. sulfurreducens (B), mineral mediated mDIET between G. metallireducens and G. sulfurreducens with nano-sized minerals (D) or GAC (E) in the presence of ethanol as the electron donor and fumarate as the electron acceptor. DIET in a co-culture of G. metallireducens and Methanosaeta harudinacea where ethanol was used as electron donor and CO₂ is reduced to CH₄ by Methanosaeta using electrons received directly from G. metallireducens via bDIET (C).