Cultivation of Rhodobacter sphaeroides in the stirred bioreactor with different feeding strategies for CoQ(10) production.

The logistic growth model combined with the Luedeking-Piret equation was adopted in this study to model the batch production of CoQ(10) in the cultivation of Rhodobacter sphaeroides. The simulation results indicated that CoQ(10) production was a primary metabolite. As being a primary metabolite, a longer cell growing stage would tend to accumulate more biomass and lead to a higher CoQ(10) concentration being produced. In this context, a fed-batch operation by molasses feeding was performed to increase the biomass and subsequent CoQ(10) production. Three different molasses feeding strategies were operated in this study. Results suggested that the fed-batch operation with molasses controlled at 10 + or - 1 g/l could increase the cell mass and CoQ(10) concentration to reach their maximum values of 18.6 g/l and 83.8 mg/l, respectively, nearly 2.2 times and 1.9 times their respective values obtained in the batch cultivation.