High Biofilm Conductivity Maintained Despite Anode Potential Changes in a Geobacter‐Enriched Biofilm

This study systematically assessed intracellular electron transfer (IET) and extracellular electron transfer (EET) kinetics with respect to anode potential (Eanode) in a mixed‐culture biofilm anode enriched with Geobacter spp. High biofilm conductivity (0.96–1.24 mS cm−1) was maintained during Eanode changes from −0.2 to +0.2 V versus the standard hydrogen electrode (SHE), although the steady‐state current density significantly decreased from 2.05 to 0.35 A m−2 in a microbial electrochemical cell. Substantial increase of the Treponema population was observed in the biofilm anode at Eanode=+0.2 V, which reduced intracellular electron‐transfer kinetics associated with the maximum specific substrate‐utilization rate by a factor of ten. This result suggests that fast EET kinetics can be maintained under dynamic Eanode conditions in a highly conductive biofilm anode as a result of shift of main EET players in the biofilm anode, although Eanode changes can influence IET kinetics.