Effect of Concomitant Lycopene Biosynthesis on CoQ10 Accumulation in Transformed Escherichia coli Strains

CoQ10 and lycopene are isoprenoid compounds with nutraceutical and pharmaceutical benefits. In this study, the effect of concomitant lycopene biosynthesis on CoQ10 accumulation in transformed Escherichia coli DH5α was studied. A lycopene production pathway including geranylgeranyl diphosphate synthase (crtE), phytoene synthase (crtB), and phytoene desaturase (crtI) from Erwinia herbicola was constructed in two CoQ10-producing E. coli strains. E. coli Ba and E. coli Br containing dds orthologs encoding for decaprenyl diphosphate synthase (Dds), respectively from Agrobacterium tumefaciens and Rhodobacter sphaeroides were transformed by the lycopene pathway resulting in E. coli Ba-lyc and E. coli Br-lyc. The lycopene pathway in E. coli Br-lyc interestingly resulted in a significant increase in CoQ10 production from 564 ± 28 to 989 ± 22 mg /g DCW. To confirm that the improvement of CoQ10 production in E. coli Br-lyc was due to lycopene biosynthesis and not just geranylgeranyl diphosphate formation in the lycopene pathway, crtE was only introduced into E. coli Ba and E. coli Br strains. Surprisingly, crtE expression had adverse effects on CoQ10 production in both strains. The results shed light on the Dds-catalyzed reaction as a bottleneck controlled by precursors; and the efficiency of a parallel lycopene pathway to streamline the flow of metabolites.