Genetic engineering strategies for performance enhancement of bioelectrochemical systems: A review

Abstract Bioelectrochemical system (BES) is a microbial metabolism based innovative technology that offers sustainable energy solution. Electroactive microbes possess unique cellular features for direct and indirect extracellular electron transfer (EET) to electrodes in BES. Genetic engineering paves the path to augment low EET rate and limited metabolic capacity of native electroactive microbes; or to confer EET ability onto non-electroactive microbes. A critical analysis of such gene modification strategies is required to explore its role in establishing efficient and promising BES. In this review, the five major types of BES are briefly discussed based upon its downstream application. Further, the EET mechanisms of model electroactive microbes are summarized with their gene modification targets; for enhancing EET and metabolic capacity. The key findings of this review are: cytochromes, pilin and electron shuttles are the major gene targets for improving EET rate, and metabolic genes are targeted for H2 and valuable product synthesis. BES application where genetic engineering strategies have been less explored and holds potential have been identified. Finally, the critical review and the future perspective of BES are summarized.