<Emphasis Type="Italic">Gluconobacter oxydans</Emphasis> NAD-dependent, <Emphasis Type="SmallCaps">D</Emphasis>-fructose reducing,polyol dehydrogenases activity: screening,medium optimisation and application for enzymatic polyol production |
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Authors: | Sofie?Parmentier Joeri?Beauprez Filip?Arnaut Wim?Soetaert Email author" target="_blank">Erick?J?VandammeEmail author |
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Institution: | (1) Department of Biochemical and Microbial technology, Ghent University, Coupure links 653, B-9000 Ghent, Belgium;(2) Puratos N.V., Industrialaan 25, B-1702 Groot-Bijgaarden, Belgium |
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Abstract: | Gluconobacter oxydans LMG 1489 was selected as the best strain for NAD(P)-dependent polyol dehydrogenase production. The highest enzyme activities were obtained when this strain was cultivated on a medium consisting of 30 g glycerol l–1, 7.2 g peptone l–1 and 1.8 g yeast extract l–1. Two D-fructose reducing, NAD-dependent intracellular enzymes were present in the G. oxydans cell-free extract: sorbitol dehydrogenase, and mannitol dehydrogenase. Substrate reduction occurred optimally at a low pH (pH 6), while the optimum for substrate oxidation was situated at alkaline pHs (pH 9.5–10.5). The mannitol dehydrogenase was more thermostable than the sorbitol dehydrogenase. The cell-free extract could be used to produce D-mannitol and D-sorbitol enzymatically from D-fructose. Efficient coenzyme regeneration was accomplished by formate dehydrogenase-mediated oxidation of formate into CO2. |
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Keywords: | coenzyme regeneration Gluconobacter oxydans polyol dehydrogenase |
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