Extracellular electron transfer EET mechanisms

EET mechanisms are nearly as diverse as the bacteria that perform them. Some bacteria transfer electrons to electrodes efficiently on their own while others need help in the form of exogenous redox molecules. Some of the most proficient exoelectrogens likely employ some combination of the mechanisms discussed here (Fig. 9.2). Understanding these mechanisms and how they interplay is integral to future engineering efforts of MFCs along with other bioelectrochemical systems. 

Redox active proteins located on the outer membrane of some cells, such as c-type cytochromes and iron-sulfur proteins, have the ability to transfer electrons directly to electrodes (Rabaey, 2010). This mechanism has been demonstrated for several different species of bacteria, but most in-depth studies of direct contact mechanisms have focused on Geobacter sulfurreducens due to the availability of a genome sequence and presence of over 100 different types of cytochromes (Methe et ah, 2003). 

---