Enhancing photocatalytic hydrogen production from engineered Escherichia coli-biohybrid system via intracellular electron redirection

The development of biotic-abiotic photosynthetic systems is becoming one of the most promising strategies towards the thirsty demand for sustainable energy production. However, considerable efforts are still required to further optimize the design and avoid the utilization of high-value substances while achieving highly efficient hydrogen production. Here we show a way to construct an Escherichia coli (E. coli)-quantum dots hybrid system by expressing ferredoxin (Fd), Fd-NAD(P)⁺ reductase (FNR), and [FeFe]-hydrogenase ([FeFe]H₂ase) as a potential biocatalyst. We reveal that electrons originating from the quantum dots could be redirected through the newly established electron transport chain NADH/NAD⁺-FNR-Fd to [FeFe]H₂ase, which contributes a key mechanism to boost the highest H₂ production activity (3149.5 μmol g_dcw⁻¹h⁻¹) by only using glycerol as the carbon source. Our work sheds light on the advantages of an intracellular biological hybrid system by combining the photocatalytic capacity with the optimized metabolic power to produce biofuels.