Electrodriven H2 Production in Escherichia coli: Rational Design and Mechanistic Studies of the Electron Uptake Process

Abstract Electromicrobial production systems, which use electrons from renewable energy sources to drive microbial metabolism towards desired products, are considered a promising strategy for future energy conversion and sustainable synthesis technologies. However, electron transport to microbes remains a critical yet poorly understood process. This hinders the rational design of these systems for viable energy efficiencies. Here, we report the construction of an efficient redox power-transport unit that converts electrons into internally generated H₂, which can either be harvested directly or used as reducing power within the cell to drive Escherichia coli metabolism towards more complex products. Efficient conversion of electrons supplied by the electronic circuit to H₂ within the cell is achieved by engineering E. coli with functional [Fe-Fe] hydrogenase from the green algae Chlamydomonas reinhardtii (CrHydA1) and selecting a suitable electron transfer mediator. The system's design is guided by a developed kinetic model, which provides insights into the mechanism and kinetics of the electron uptake process.