Photoelectrocatalytic-microbial biohybrid for succinic acid synthesis

Succinic acid is an important platform chemical traditionally produced via energy-intensive and environmentally unfriendly processes. Actinobacillus succinogenes offers a sustainable biosynthetic route, yet its productivity is constrained by limited intracellular electron transfer. Here, we develop a photoelectrocatalytic-microbial biohybrid system to overcome these metabolic bottlenecks. Adaptive laboratory evolution using gold nanoparticles establishes an enhanced charge-transfer pathway in Actinobacillus succinogenes, which is subsequently immobilized on a layer-by-layer NiO@PAA@NHS (NiO nanosheets coated with hydrogel of poly acrylic acid (PAA) grafted with N-Hydroxysuccinimide (NHS)) photoelectrode to construct a NiO@PAA@NHS/Au@ Actinobacillus succinogenes biohybrid. Under simulated solar illumination at -0.3 V vs. RHE, the system delivers a photocurrent density of 1.9 mA cm^-2, a CO₂ conversion efficiency of 67%, and a succinic acid production rate of 1.41 ± 0.04 g L^-1 h^-1 cm^-2. This work demonstrates an effective strategy for coupling solar energy with microbial metabolism for scalable, carbon-neutral chemical production.