Enhancing Microbial Electron Transfer Through Synthetic Biology and Biohybrid Approaches

Abstract

Traditional microbial synthesis of chemicals and fuels often rely on energy-rich feedstocks such as glucose, raising ethical concerns as they are directly competing with the food supply. Therefore, it is imperative to develop novel processes that rely on cheap, sustainable, and abundant resources whilst providing carbon circularity. Microbial Electrochemical Technologies (MET) offer unique opportunities to facilitate the conversion of chemicals to electrical energy or vice-versa, by harnessing the metabolic processes of bacteria to valorise a range of waste products, including greenhouse gases (GHS). However, the strict growth and nutrient requirements of industrially relevant bacteria, combined with low efficiencies of native extracellular electron transfer mechanisms (EET) reduce the potential for industrial scalability. In this work, we review the most significant advancements in techniques aimed at improving and modulating the efficiency of microbial EET, giving an objective and balanced view of current controversies surrounding the physiology of microbial electron transfer, alongside the methods used to wire microbial redox centres with the electrodes of bioelectrochemical systems via conductive nanomaterials. The EET rates achieved via biological and biohybrid approaches will be compared and the limitations of the two approaches described below.