Coenzyme Q10 production by Rhodobacter sphaeroides in stirred tank and in airlift bioreactor.

A higher Coenzyme Q(10) (CoQ(10)) concentration of 25.04 mg/l was found in airlift bioreactor than the value of 18.11 mg/l obtained in stirred tank under the aerobic-dark cultivation of Rhodobacter sphaeroides. Aeration rate didn't show obvious impact to CoQ(10) production in airlift bioreactor. The fed-batch operation in airlift bioreactor could increase the biomass concentration and led to the maximum CoQ(10) concentration of 33.91 mg/l measured, but a lower CoQ(10) cell content (3.5 mg CoQ(10)/DCW) was observed in the fed-batch operation as compared to the batch operation. To enhance the CoQ(10) content, an aeration-change strategy was proposed in the fed-batch operation of airlift bioreactor. This strategy led to the maximum CoQ(10) concentration of 45.65 mg/l, a 35% increase as compared to the simple fed-batch operation. The results of this study suggested that a fed-batch operation in airlift bioreactor accompanying aeration-change could be suitable for CoQ(10) production.