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.
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.
Ji
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A
Department of Pharmacy, Shandong University, Jinan, China.
Gao
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P
D005942:Gluconates / Q000378:metabolism*; D020600:Gluconobacter oxydans / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D042843:Glucose 1-Dehydrogenase; D005948:Glucose Dehydrogenases / Q000378:metabolism; D007783:Lactones; D009097:Multienzyme Complexes / Q000096:biosynthesis*; D009249:NADP / Q000096:biosynthesis; D013379:Substrate Specificity / Q000502:physiology; D013400:Sugar Acids / Q000378:metabolism*; D013401:Sugar Alcohol Dehydrogenases / Q000378:metabolism
D005942:Gluconates; D007783:Lactones; D009097:Multienzyme Complexes; D013400:Sugar Acids; C032616:2,5-diketogluconic acid; D009249:NADP; D013401:Sugar Alcohol Dehydrogenases; C053163:2,5-diketo-D-gluconate 5-reductase; D005948:Glucose Dehydrogenases; D042843:Glucose 1-Dehydrogenase; C011491:provitamin C; D005947:Glucose; C030691:gluconic acid; C010730:beta-glucono-1,5-lactone