Research PaperSynergic regulation of redox potential and oxygen uptake to enhance production of coenzyme Q10 in Rhodobacter sphaeroides

•Enhanced CoQ10 production in R. sphaeroides by a novel synergic regulation method.•Overexpression of gapA-1 effectively improved the CoQ10 content in R. sphaeroides.•The order of gapA-1 and vgb in polycistrons influenced both cell growth and activity.•Highest CoQ10 production among R. sphaeroides constructed by metabolic engineering.

The physiological role of Coenzyme Q10 (CoQ10) as an electron carrier suggests its association with redox potential. Overexpression of glyceraldehyde-3-phosphate dehydrogenase type I (gapA-1) in Rhodobacter sphaeroides elevated the NADH/NAD+ ratio and meanwhile enhanced the CoQ10 content by 58%, but at the sacrifice of biomass. On the other hand, Vitreoscilla hemoglobin was heterologously expressed to enhance the oxygen uptake ability of the cells, leading to 127% improvement of biomass. Subsequent coexpression of gapA-1 and vgb resulted in a CoQ10 titer of 83.24 mg/L, representing 71% improvement as compared to the control strain RspMCS. When gapA-1 and vgb genes were co-expressed in a previously created strain RspMQd [1], 163.5 mg/L of CoQ10 was produced. Finally, 600 mg/L of CoQ10 production was achieved in fed-batch fermentation. These results demonstrated the synergic effect of redox potential regulation and oxygen uptake improvement on enhancing CoQ10 production in R. sphaeroides.