Coenzyme Q production by metabolic engineered Escherichia coli strains in defined medium

Coenzyme Q (CoQ) plays an important role as an electron transporter in the respiratory chain. It is formed from a benzoquinone ring and an isoprenoid chain of a specific length depending on the organism. We constructed an engineered Escherichia coli strain ( menF ) unable to produce demethylmenaquinone and menaquinone, compounds that compete for both chorismate, precursor of the benzoquinone ring, and the isoprenoid chain involved in CoQ biosynthesis. In addition, a mutant strain ( entC ) unable to produce enterobactin, high-affinity siderophore, synthesized from chorismate, and a double mutant ( entC–menF ) were constructed. The use of glucose or glycerol as carbon sources was also evaluated for the production of CoQ 8 in these strains. The double mutant ( entC–menF ) showed 18% increase in CoQ 8 -specific content compared to the control strain; however, the single-mutant strains did not show statistically significant differences in CoQ 8 -specific content respect to the control, in glucose medium in bioreactor experiments. Glycerol was significantly superior compared to glucose for the production of CoQ 8 in E. coli , where the CoQ 8 -specific content increased 126% and 53% in the control and double-mutant strain, respectively. The expression of genes related to CoQ 8 biosynthesis is reported, where the entC–menF double-mutant strain showed a significant increase in the expression of CoQ 8 biosynthesis-related genes when glycerol was used as sole carbon source. The control strain did not show gene expression difference between both carbon sources, indicating a possible regulation at a different level.