Improvement of cultivation medium for enhanced production of coenzyme Q10 by photosynthetic Rhodospirillum rubrum

Coenzyme Q10 (CoQ10), a potent antioxidative dietary supplement, was produced by submerged fermentation using an anaerobic photosynthetic bacteria Rhodospirillum rubrum ATCC 25852 instead of chemical synthesis or solvent extraction. Five nutritional factors, including malic acid, yeast extract, (NH4)2SO4, MgSO4·7H2O, and ferric citrate, were optimized for CoQ10 production using response surface methodology (RSM) in static test tube cultures. The optimal medium for CoQ10 production were (g/l): malic acid, 2.5; yeast extract, 1.29; (NH4)2SO4, 1.34; MgSO4·7H2O, 0.20; 0.90 g/l K2HPO4, 0.90; KH2PO4, 0.60; ferric citrate, 0.08; and EDTA, 0.02. The highest yield of CoQ10 was 9.76 mg/l, in agreement with the RSM predicted yield (9.63 mg/l). The yield of CoQ10 in a 3-l fermentor was higher than that achieved in the static culture and reached 10.81 mg/l, which could be attributed to the constant agitation (400 rpm) that enhanced cell–substrate contact throughout the fermentation. The optimal medium compositions acquired in the present study provide a solid foundation for further improvement and optimization of fermentation processes that can be suitable for industrial-scale production of CoQ10.