• biofuels;
  • electrochemistry;
  • electron transport;
  • fuel cells;
  • microbes


The number of investigations involving bioelectrochemical systems (BES), processes in which microorganisms catalyze electrode reactions, is increasing while their mechanisms remain unresolved. Geobacter sulfurreducens strain DL1 is a model electrode catalyst that forms multimicrobe-thick biofilms on anodes that catalyze the oxidation of acetate to result in an electric current. Here, we report the characterization by cyclic voltammetry (CV) of DL1 biofilm-modified anodes (biofilm anodes) performed during biofilm development. This characterization, based on our recently reported model of biofilm anode catalytic activity, indicates the following. 1) As a biofilm grows, catalytic activity scales linearly with the amount of anode-accessible redox cofactor in the biofilm. This observation is consistent with a catalytic activity that is limited during biofilm growth by electron transport from within cells to the extracellular redox cofactor. 2) Distinct voltammetric features are exhibited that reflect the presence of a redox cofactor expressed by cells that initially colonize an anode that is not involved in catalytic current generation