1,3-Propanediol formation with product-tolerant mutants of Clostridium butyricum DSM 5431 in continuous culture: productivity, carbon and electron flow |
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Authors: | Reimann Abbad-Andaloussi Biebl & Petitdemange |
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Institution: | Gesellschaft für Biotechnologische Forschung GmbH, Braunschweig, Germany,;Laboratoire de Chimie Biologique 1, UniversitéHenri Poincaré, Nancy, Vandoeuvre-lès-Nancy Cedex, France |
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Abstract: | Glycerol fermentation and product formation of two product-tolerant mutants of Clostridium butyricum DSM 5431 were investigated in continuous culture at increasing glycerol feed concentrations. Under conditions of glycerol excess (above 55 g l?1 at D = 0·15 h?1), the mutants maintained a constant level of glycerol consumption and product formation, whereas the parent strain exhibited a substantial decrease in substrate conversion, 1,3-propanediol and butyrate formation, and an increase in acetate formation. The activities of the glycerol dehydrogenase, the glycerol dehydratase and the 1,3-propanediol dehydrogenase showed only slight changes with glycerol concentrations in the mutants, but dropped markedly at high concentrations in the wild type. Intracellular concentrations of NADH, NAD + and acetyl-CoA remained at a relatively constant level in the mutants, but increased sharply with the wild type strain. The NADH content was always higher than the NAD + content in the mutants as well as in the wild type. |
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