Improving coenzyme Q10 yield of Rhodobacter sphaeroides via modifying redox respiration chain

The physiological function of Coenzyme Q10 (CoQ10) reveals its association with aerobic respiration. Decreasing oxygen supply reduced R. sphaeroides CoQ10 content suggesting there might be close correlation between redox respiration chain (RRC) activity and CoQ10 biosynthesis. To elucidate the influence of RRC activity on CoQ10 biosynthesis, genes (sdhB, ccoN and cytaa3) encoding the catalytic subunit of RRC components were individually deleted. Comparing with the wild type (WT), sdhB defection significantly promoted CoQ10 content especially under low oxygen supply conditions, but the biomass of △sdhB was quite less than that of WT. To further explore the potential of △sdhB in CoQ10 production, a rational two-step oxygen supply culture strategy was applied to enhance bacterial growth and CoQ10 yield in a lab-scale bioreactor. Under this condition, CoQ10 yield was enhanced by 41.1% than that of WT and biomass was increased with 7.6% improvement over WT. This study provided a novel guidance for promoting R. sphaeroides CoQ10 yield via regulating RRC activity coupled with rational culture protocol.