Uptake of self-secreted flavins as bound cofactors for extracellular electron transfer in Geobacter species

Geobacter species are among the most efficient current-producing bacterial species, yet their electron-transfer mechanisms have been scarcely investigated at the molecular level. Here, we provide evidence that Geobacter cells secrete and utilize riboflavin as a bound-cofactor in outer-membrane c-type cytochromes. This finding highlights the potential roles of riboflavin as a major electron carrier in current production.