Fig. 3

Mechanism of electron transport by bacterial nanowires and/or outer membrane cytochromes. Microbial biofilms produce electricity by long range electron transport using a dense forest of 15 μm long nanowires. This is made possible in exo-electrogenic bacteria using a symphony of proteins including MAC A, Periplasmic cytochromes, outer membrane cytochromes such as OmcZ and PilA, principle component of nanowires. Other cytochromes such as omcB and omcE, omcS and omcT play an important role in the reduction of metal oxides and especially in the short-range electron transport. As shown in the figure, anode surface modification with chemical treatment, impregnation of synthetic conductive nanowires on the anode surface, and/or functionalization of electron carriers on the vertically aligned carbon nanotubules, improves the electricity generation in MFCs