Optimized light supply strategy comprehensively increases the synthesis of high-value cell inclusions in Rhodopseudomonas palustris using food waste fermentation broth: Process optimization and biosynthetic mechanism.

The bioconversion of purple non-sulfur photosynthetic bacteria (PNSB) based on real food waste (FW) fermentation broth is crucial for FW resource recovery. This study enhanced the bioconversion efficiency of FW fermentation broth by PNSB through light intensity and photoperiod optimization, while elucidating the synthesis mechanisms of high-value cell inclusions. The results demonstrated that 4500 lx-L/D = 16/8 significantly enhanced R. palustris SYJ-1's organic/nitrogen utilization efficiency and intracellular product synthesis. Proteomic analysis revealed that 4500 lx promoted the synthesis of geranylgeranyl pyrophosphate (GGPP), a precursor for photosynthetic pigments and coenzyme Q (CoQ), increasing the contents of carotenoids, bacteriochlorophyll, and CoQ by 3.31-, 2.86-, 3.03-fold, respectively. Dark stimulation alleviated light-induced metabolic constraints by enhancing GGPP conversion and 4-hydroxybenzoate (another precursor of CoQ) synthesis/modification, further promoting the production of these compounds. This study significantly advances the understanding of intracellular products synthesis in PNSB and provides a novel feasible approach for FW resource recovery.