Solar Energy for Value-Added Chemical Production by Light- Powered Microbial Factories

The light-driven material-microorganism biohybrid system has the potential to transfer solar energy for chemical production. However, few studies have reported the construction of biohybrid systems using light-responsive materials with nonmodel strains that have been widely used in practical industrial production for value-added chemicals, especially with regard to the mechanism of action of photogenerated charges in the cytoplasm, probably due to the complexity of their anabolic pathways. Herein, a biohybrid system as a research mode was constructed by electrostatically self-assembling a highly efficient light-harvesting material of graphite-phase nitrided carbon (g-C3N4) nanosheets with nonmodel strains (Phaffia rhodozyma) for synthesis of nutritional chemical astaxanthin. The biohybrid interface enabled efficient separation, transfer, and transport of photogenerated charges from g-C3N4 into the interior of P. rhodozyma, which improved the substance metabolism and the energy metabolism of P. rhodozyma. Notably, photogenerated charges can significantly promote the accumulation of precursors along the astaxanthin anabolic pathway and enhance the cytoplasmic redox environment and ATP levels in the interior of P. rhodozyma, even under adverse conditions (such as enzyme inhibitors), thus increasing the yield of astaxanthin compared to the traditional culture of P. rhodozyma. This study not only provides new ideas for converting solar energy into value-added chemicals, but it also provides guidance for regulating microbial synthesis plants.