Abstract:Coenzyme Q 10(CoQ10) is a natural antioxidant and cell metabolic activator, possessing several important biological properties, such as eliminating free radicals, maintaining cell membrane permeability, and improving immune function. It is of great value to develop high-yield CoQ10 strain and realize high-efficient synthesis of functional compounds by fermentation. In this work, a potent CoQ10-producing strain YLL-13 was isolated from the silt of a sewage treatment plant. Based on the morphological observation, biochemical characteristics analysis and 16S rDNA sequence alignment, the strain was identified as Rhodobacter sphaeroides and named as R. sphaeroides YLL-13. In further, a high-yield mutant strain was screened by nitrosoguanidine chemical mutagenesisusing R. sphaeroides Yll-13 as the starting strainand Vitamin K3 and p-hydroxybenzoic acid(pHBA) as the compound screening markers. A genetically stable CoQ10mutant with high yield of CoQ10, R. sphaeroides YLL-13-T,was achieved by mutagenesis. This strain had relatively low carotenoid synthesis, high growth rate and high CoQ10 accumulation characteristics. In the studied fermentation system, the biomass, CoQ10 concentration and specific CoQ10 content of the mutant strain YLL-13-T after 120 h fermentation were 83.5 g/L, 1.04 g/L and 12.46 mg/g(DCW) respectively, which were 12.3%, 42.5% and 23.6% higher than those of original wild-type strain, showing a good prospect of industrial application.
