Batch and fed-batch production of coenzyme Q₁₀ in recombinant Escherichia coli containing the decaprenyl diphosphate synthase gene from Gluconobacter suboxydans

Abstract

Coenzyme Q₁₀ (CoQ₁₀) is a quinine consisting of ten units of the isoprenoid side-chain. Because it limits the oxidative attack of free radicals to DNA and lipids, CoQ₁₀ has been used as an antioxidant for foods, cosmetics and pharmaceuticals. Decaprenyl diphosphate synthase (DPS) is the key enzyme for synthesis of the decaprenyl tail in CoQ₁₀ with isopentenyl diphosphate. The ddsA gene coding for DPS from Gluconobacter suboxydans was expressed under the control of an Escherichia coli constitutive promoter. Analysis of the cell extract in recombinant E. coli BL21/pACDdsA by high performance liquid chromatography and mass spectrometry showed that CoQ₁₀ rather than endogenous CoQ₈ was biologically synthesized as the major coenzyme Q. Expression of the ddsA gene with low copy number led to the accumulation of CoQ₁₀ to 0.97 mg l⁻¹ in batch fermentation. A high cell density (103 g l⁻¹) in fed-batch fermentation of E. coli BL21/pACDdsA increased the CoQ₁₀ concentration to 25.5 mg l ⁻¹ and its productivity to 0.67 mg l⁻¹ h⁻¹, which were 26.0 and 6.9 times higher than the corresponding values for batch fermentation.