Bioelectrochemical systems (BES)

In BES, electrochemically active bacteria catalyze at least one of the electrode reactions of an electrochemical cell. In case of a biological anode, an oxidation reaction is catalyzed by bacteria, from example the oxidation of acetate to bicarbonate, protons and electrons. The electrons are transferred by the bacteria to a solid electrode (e.g. made of carbon). In case of a biological cathode, a reduction reaction is catalyzed by bacteria. Examples are the reduction of protons to hydrogen gas

(H2), Cu2+ to Cu or CO2  to organics such as CH4. Bioelectrochemical systems can be operated in fuel cell mode (microbial fuel cell) or electrolysis mode (microbial electrolysis cell)