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

Abstract The physiological role of Coenzyme Q 10 (CoQ 10 ) 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 CoQ 10 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 CoQ 10 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 CoQ 10 was produced. Finally, 600 mg/L of CoQ 10 production was achieved in fed-batch fermentation. These results demonstrated the synergic effect of redox potential regulation and oxygen uptake improvement on enhancing CoQ 10 production in R. sphaeroides .