Monday, May 4, 2009
11-17

Improvement of coenzyme Q10 production by ispB knockout and dxs overexpression in recombinant Escherichia coli expressing Agrobacterium tumefaciens decaprenyl diphosphate synthase

Jin-Ho Choi1, Seung-Ryel Han2, Ye-Ji Lee2, Dae-Hyuk Kweon3, Yeon-Woo Ryu4, Yong-Cheol Park5, and Jin-Ho Seo2. (1) Energy Biosciences Institute, University of Illinois at Urbana-Champaign, 1206 W. Gregory Dr, Urbana, IL 61801, (2) Deparment of Agricultural Biotechnology, Seoul National University, San 56-1, Shilim-dong, Kwanak-gu, Seoul, South Korea, (3) School of Biotechnology and Bioengineering, Sungkyunkwan University, Chonchon-dong, Suwon, South Korea, (4) Department of Molecular Science and Technology, Ajou university, San 5, Wonchon-dong, Yeongtong-gu, Suwon, South Korea, (5) Center for Agricultural Biomaterials, Seoul National University, San 56-1, Sillim-dong, Gwanak-gu, Seoul, South Korea

Coenzyme Q10 (CoQ10) is a lipid-soluble benzoquinone essential for ATP generation and used as an antioxidant in food supplement. Biotechnological production of coenzyme Q10 was performed in recombinant Escherichia coli expressing decaprenyl diphosphate synthase (Dps) from Agrobacterium tumefaciens. From batch fermentations of several dps expression systems containing different promoters and replication origins, the modified Plac constitutive promoter and ColE1 ori gave the best results of CoQ10 production. Even though CoQ10 accumulated inside the cells, a major by-product of endogenous CoQ8 was produced inevitably. To prevent CoQ8 production and concomitantly increase CoQ10 titer, the chromosomal ispB gene encoding octaprenyl diphosphate synthase was deleted by homologous recombination. Deletion of the ispB gene and expression of the dps gene led to the production of CoQ10 without CoQ8 and CoQ9 accumulation. In addition, Dxs which was already known to boost the pool of a CoQ10 intermediate, isopentenyl diphosphate, was coexpressed in recombinant E. coli BL21(DE3) strain expressing the dps gene and deficient in the chromosomal ispB gene. Batch fermentation in LB medium resulted in 1.40 mg/g of specific coenzyme Q10. Fed-batch fermentation of recombinant E. coli BL21(DE3)ΔispB/pAP1+pDXS in a defined medium with 20 g/L initial glucose was carried out by feeding 800 g/L glucose with the pH-stat strategy. As a result, a final coenzyme Q10 concentration of 99.4 mg/L and its volumetric productivity of 3.11 mg/L-hr were obtained in 32 hr of fed-batch fermentation.

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See more of The 31st Symposium on Biotechnology for Fuels and Chemicals (May 3-6, 2009)