Substrate selectivity of Gluconobacter oxydans for production of 2,5-diketo-D-gluconic acid and synthesis of 2-keto-L-gulonic acid in a multienzyme system |
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Authors: | Ji A Gao P |
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Affiliation: | (1) Department of Pharmacy, Shandong University, 250012 Jinan, Shandong, China;(2) State Key Laboratory of Microbial Technology, Shandong University, 250100 Jinan, Shandong, China |
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Abstract: | Substrate selectivity of Gluconobacter oxydans (ATCC 9937) for 2,5-diketo-d-gluconic acid (2,5-DKG) production was investigated with glucose, gluconic acid, and gluconolactone in different concentrations using a resting-cell system. The results show that gluconic acid was utilized favorably by G. oxydans as substrate to produce 2,5-DKG. The strain was coupled with glucose dehydrogenase (GDH) and 2,5-DKG reductase for synthesis of 2-keto-l-gulonic acid (2-KLG), a direct precursor of l-ascorbic acid, from glucose. NADP and NADPH were regenerated between GDH and 2,5-DKG reductase. The mole yield of 2-KLG of this multienzyme system was 16.8%. There are three advantages for using the resting cells of G. oxydans to connect GDH with 2,5-DKG reductase for production of 2-KLG: gluconate produced by GDH may immediately be transformed into 2,5-DKG so that a series of problems generally caused by the accumulation of gluconate would be avoided; 2,5-DKG is supplied directly and continuously for 2,5-DKG reductase, so it is unnecessary to take special measures to deal with this unstable substrate as it was in Sonoyama’s tandem fermentation process; and NADP(H) was regenerated within the system without any other components or systems. |
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Keywords: | 2-Keto- font-variant:small-caps" >l-gulonic acid Gluconobacter oxydans glucose dehydrogenase 2,5-diketo- font-variant:small-caps" >d-gluconic acid reductase 2,5-diketo- font-variant:small-caps" >d-gluconic acid font-variant:small-caps" >l-ascorbic acid glucose gluconic acid NADP(H) regeneration |
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