Enhanced butanol production through intracellular NADH regeneration in CdSe-C. acetobutylicumg semi-photosynthetic biohybrid system.

Current environmental challenges and energy crises highlight the urgent need for a transition in energy mix. In this study, an innovative semi-photosynthetic biohybrid system that combined light-activated cadmium selenide quantum dots (CdSe QDs) with engineered Gram-positive anaerobic bacteria, Clostridium acetobutylicum_g (C. acetobutylicum_g), was developed to enhance renewable butanol production. The results demonstrated that CdSe QDs could be biosynthesized intracellularly within C. acetobutylicum_g through the introduction of glutathione pathway, without causing significant damage to bacteria. Furthermore, this system showed remarkable tolerance to butanol and weak acids. Under illumination, the biological synthesized CdSe QDs enabled C. acetobutylicum_g to achieve a 45.5 % increase in NADH/NAD⁺ ratio compared to C. acetobutylicum_g without CdSe QDs. When utilizing undetoxified rice straw hydrolysate in photo-fermentation, this system achieved a butanol titer of 14.82 g/L and a yield of 0.29 g/g. Overall, this work aims to effectively harness solar energy and biomass resources for sustainable clean biofuel production.