Frozen samples of G. sulfurreducens (strain PCA, ATCC 51573) were cultured in an anaerobic glove box (10% H2, 10% CO2 and 80% N2) for 7 days. The subculture medium included the following quantities per liter of distilled water: 1.5 g NH4Cl, 0.6 g NaH2PO4, 0.1 g KCl, 2.5 g NaHCO3, 0.82 g CH3COONa (for a 10 mM sodium acetate solution), 8 g Na2C4H2O4 (for a 40 mM sodium fumarate solution), 10 mL vitamin supplement (ATCC® MD-VS™) and 10 mL trace mineral supplement (ATCC® MD-TMS™). All chemical compounds were dissolved in distilled water, and the solutions were autoclaved at 110°C for 20 minutes, except for sodium fumarate, which was added later through a sterilized filter. The produced sub-culture was injected into the 3-electrode microfluidic bioelectrochemical system (BES) via syringe pumps (PhD 2000, Harvard Apparatus, MA) with the culture media at a flow rate Q of 0.5 mL h -1 while the WE was poised at 0.4 mV versus the gold RE, which is approximately equivalent to 200 mV vs. SHE. While maintaining the same flow rate and other experimental parameters, the nutrient solution was switched to a sterile one containing no fumarate, during which time the bacteria that had previously found the electrode were able to grow.