Multiple Strategies for Metabolic Engineering of Escherichia coli for Efficient Production of Coenzyme Q10

Escherichia coli BW25113 was metabolically engineered for CoQ10 production by replacing ispB with ddsA from Gluconobacter suboxydans. Effects of precursor balance and reduced nicotinamide-adenine dinucleotide phosphate (NADPH) availability on CoQ10 production in E. coli were investigated. The knockout of pykFA along with pck overexpression could maintain a balance between glyceraldehyde 3-phosphate and pyruvate, increasing CoQ10 production. Replacement of native NAD-dependent gapA with NADP-dependent gapC from Clostridium acetobutylicum, together with the overexpression of gapC, could increase NADPH availability and then enhanced CoQ10 production. Three effects, overexpressions of various genes in CoQ biosynthesis and central metabolism, different vectors and culture conditions on CoQ10 production in E. coli, were all investigated. The investigation of different vectors indicated that low copy number vector may be more beneficial for CoQ10 production in E. coli. The recombinant E. coli (ΔispB::ddsA, ΔpykFA and ΔgapA::gapC), harboring the two plasmids encoding pck, dxs, idi and ubiCA genes under the control of PT5 on pQE30, ispA, ddsA from Gluconobacter suboxydans and gapC from Clostridium acetobutylicum under the control of PBAD on pBAD33, could produce CoQ10 up to 3.24 mg·g−1 dry cell mass simply by changing medium from M9YG to SOB with phosphate salt and initial culture pH from 7.0 to 5.5. The yield is unprecedented and 1.33 times of the highest production so far in E. coli.