Harnessing photoenzymatic reactions for unnatural biosynthesis in microorganisms

Photoenzymatic catalysis enables new-to-nature transformations, but its
scalability is limited by high enzyme loading, costly cofactors, and
radical-induced instability. Here we report the integration of
light-driven photoenzymatic reactions into the cellular metabolism of
Escherichia coli, bridging flavin-based photobiocatalysis with
biosynthesis. Using synthetic biology strategies, we engineered microbial
cells to continuously produce olefin substrates and ene-reductase
photoenzyme while regenerating cofactors directly from glucose. By
externally supplying radical precursors or by introducing synthetic
pathways for their in situ production, we enabled fermentation-based
microbial photobiosynthesis, achieving high titers and demonstrating its
feasibility for scale-up in bioreactor. This approach extends
photobiocatalysis from in vitro applications to in vivo semi-biosynthesis
and complete biosynthesis, revealing its full potential for integrating
light-driven reactions into cellular metabolism.