Light-driven H₂-evolution and C=C or C=O bond hydrogenation by Shewanella oneidensis: A versatile strategy for photocatalysis by nonphotosynthetic microorganisms

Photocatalytic chemical synthesis by coupling abiotic photosensitizers to purified enzymes provides an effective way to overcome the low conversion efficiencies of natural photosynthesis while exploiting the high catalytic rates and selectivity of enzymes as renewable, earth-abundant electrocatalysts. However, the selective synthesis of multiple products requires more versatile approaches and should avoid the time-consuming and costly processes of enzyme purification. Here we demonstrate a cell-based strategy supporting light-driven H₂-evolution or the hydrogenation of C=C and C=O bonds in a non-photosynthetic microorganism. Methyl viologen shuttles photoenergized electrons from water-soluble photosensitizers to enzymes that catalyze H₂-evolution and the reduction of fumarate, pyruvate and CO₂ in Shewanella oneidensis. The predominant reaction is selected by the experimental conditions and the results allow rational development of cell-based strategies to harness nature’s intrinsic catalytic diversity for selective light-driven synthesis of a wide range of products.