Bioelectrochemical systems

A bioelectrochemical system (BES) exploits biological catalysts for anode and/or cathode reactions, or both. This chapter focuses on three different classes of microbial bioelectrocatalysts which can be distinguished, ranging from single enzymes (e.g., dehydrogenases) or enzyme arrays and organelles (e.g., mitochondria) to entire living microbial cells. It discusses the similarities and differences between conventional chemical and microbial bioelectrocatalysts. Subsequently, the chapter also discusses the principal mechanisms of the extracellular electron transfer (EET) and the technology aiming at their exploitation. Primary metabolites are directly linked to the microbial catabolic (in case of anodic biofilms) metabolism and thus mainly derive from microbial anaerobic respiration as well as fermentation, with key examples being hydrogen and sulfide. Finally, the chapter addresses the biological and electrochemical methods that allow the analysis of the microbial electron transfer (MET) and identification of the respective mediators, proteins, and microorganisms