Fig. 5

Metabolic engineering of CoQ10 pathway by nCBE series. a The biosynthetic route of ubiquinone in Rhodobacter sphaeroides 2.4.1, from the precursor decaprenyl diphosphate (DPP) and polyhydroxyalkanoates (PHA) to the final product CoQ10. Black arrows indicated the genes that were successfully knocked out and grey arrows indicated the genes that were failed to be knocked out. b The HPLC graphs of the WT and ubiquinone series genes KO mutants. The peaks at the retention time 7.37 min were definitely CoQ10, and the areas of these peaks quantitatively reflected the concentration of each sample. c The CoQ10 concentration and content of the tested strains after 5 days’ fermentation. All mutants were compared with the WT and the significant analysis of t-test was shown as (*p < 0.05; **p < 0.01; ***p < 0.001). ND meant none detected and n.s meant no significance. d The microscopic pictures of WT and ∆ubiF. The depth of dyeing qualitatively reflected the content of CoQ10