Precise regulating the specific oxygen consumption rate to strengthen the CoQ biosynthesis by Rhodobater sphaeroides.

Coenzyme Q (CoQ) is the most consumed dietary supplement and mainly biosynthesized by aerobic fermentation of Rhodobacter sphaeroides (R. sphaeroides). Oxygen supply was identified as a bottleneck for improving CoQ yield in R. sphaeroides. In this study, a precise regulation strategy based on dielectric spectroscopy (DS) was applied to further improve CoQ biosynthesis by R. sphaeroide. First, a quantitative response model among viable cells, cell morphology, and oxygen uptake rate (OUR) was established. DS could be used to detect viable R. sphaeroides cells, and the relationship among cell morphology, CoQ biosynthesis, and OUR was found to be significant. Based on this model, the online specific oxygen consumption rate (Q) control strategy was successfully applied to the CoQ fermentation process. Q controlled at 0.07 ± 0.01 × 10mmol/cell/h was most favorable for CoQ biosynthesis, resulting in a 28.3% increase in CoQ production. Based on the multi-parameters analysis and online Q control, a precise online nutrient feeding strategy was established using conductivity detected by DS. CoQ production was improved by 35%, reaching 3384 mg/L in 50 L bioreactors. This online control strategy would be effectively applied for improving industrial CoQ production, and the precise fermentation control strategy could also be applied to other fermentation process.