Bio-Photocatalytic Synergy Enables Valorization of CH4 and CO2 Into Hydrogen and 4-Hydroxybenzoate in Engineered Methanotrophic Bacteria.

Valorization of decentralized one-carbon chain (C1) resources into value-added products has garnered significant attention, owing to its dual benefits in resource recovery and carbon mitigation. To address the challenge of co-converting methane (CH4) and carbon dioxide (CO2), we developed a solar-driven biohybrid system that synergistically integrates biosynthesis and photocatalysis. The core of this system relies on a genetically engineered methanotrophic cell factory and newly designed biocompatible photocatalytic metal complexes. The methanotrophic bacteria utilize CH4 as the primary feedstock to biosynthesize 4-hydroxybenzoate (4HBA) while realizing CO2 sequestration. The photocatalytic metal complexes, meanwhile, capture formate (a metabolic byproduct of cells) to generate hydrogen (H2) and photoelectrons-with the latter directly supplying reducing power to support cellular activities in genetically tailored cells. Under optimal conditions, this solar-driven system achieved a 4HBA titer of 472.36 µg/L, a H2 yield of 0.59 mmol H2/mol CH4, and over 50% reduction in carbon emissions. The study not only establishes a feasible biomanufacturing strategy for the upcycling of C1 gaseous feedstocks but also highlights the potential of integrating biological and photochemical technologies to advance sustainable energy and environmental solutions.