Set potential regulation reveals additional oxidation peaks of Geobacter sulfurreducens anodic biofilms

Higher current densities produced in microbial fuel cells and other bioelectrochemical systems are associated with the presence of various Geobacter species. A number of electron transfer components are involved in extracellular electron transfer by the model exoelectrogen, Geobacter sulfurreducens. It has previously been shown that 5 main oxidation peaks can be identified in cyclic voltammetry scans. It is shown here that 7 separate oxidation peaks emerged over relatively long periods of time when a larger range of set potentials was used to acclimate electroactive biofilms. The potentials of oxidation peaks obtained with G. sulfurreducens biofilms acclimated at 0.60 V (vs. Ag/AgCl) were different from those that developed at − 0.46 V, and both of their peaks were different from those obtained for biofilms incubated at − 0.30 V, 0 V, and 0.30 V. These results expand the known range of potentials for which G. sulfurreducens produces identifiable oxidation peaks that could be important for extracellular electron transfer.

► Geobacter sulfurreducens produces high current densities in microbial fuel cells.
► Only a few components of this microbe's respiratory chain have been identified.
► Using cyclic voltammetry, we show the presence of up to 7 redox peaks.
► These findings expand the number of possible respiratory components for this microbe.