70 Electrochemically Enabled Sustainability
2.2.3.2 Direct Electron Transfer via Nanowires
Some microorganisms (e.g. Geobacter, Rhodoferax and Shewanella strains) can
evolve electronically conductive molecular pili (nanowires) that allow the
microorganism to reach more distant solid electron acceptors [49]. As shown
in Figure 2.6b, the pili are connected to the membrane-bound cytochromes.
These cytochromes deliver electrons to the pili, which then transfer the
electrons to metal oxides or electrode via physical contact. The conductive
nanowires make it possible for cells that are not in direct contact with the
anode surface to transfer electrons to the electrode. Thus, thick electroactive
biofilms develop on the electrode surface, resulting ...