Electrochemical roles of extracellular polymeric substances in biofilms

Most microbial cells in nature are surrounded by extracellular polymeric substances (EPS), which are fundamental components and determine the physiochemical properties of a biofilm. This review highlights the EPS properties of conductivity and redox ability from an electrochemical perspective, emphasizing recent findings that EPS play important roles in microbial extracellular electron transfer (EET). Basic information regarding EPS structure and components is required to better understand their effects on EET; future directions are briefly discussed.