Physiological response of electroactive bacteria via secretion of extracellular polymeric substances in microbial electrochemical processes: a review

Microbial electrochemical processes involving microbial catalyzed electrochemical reactions are directly/indirectly related to the electroactive bacteria (EAB) physiological secretion of extracellular polymeric substances (EPS) with favorable biofilm dispersion. EPS harbor cytochrome-like substances, and thus accelerate extracellular electron transfer (EET) processes resulting in the simultaneous removal of environmental contaminants or in the conversion of dissolved CO₂ to key-block chemicals. This review holistically documents case-studies in the last five years focusing on EAB and their physiological release of EPS in response to external stimuli. The important role played by EPS in the performance of microbial electrochemical systems and the relationship of the EPS compositional diversity with the process parameters is reviewed. Targeting the physiological response of electroactive bacteria towards the release of EPS with precise compositional diversity provides tremendous opportunities for optimizing microbial electrochemical processes. This review provides kernels, quantitative approaches and promising advanced techniques guiding further research directions in this exciting field.