title: Modification of the membrane-bound glucose oxidation system in Gluconobacter oxydans significantly increases gluconate and 5-keto-D-gluconic acid accumulation.
abstract: Gluconobacter oxydans DSM 2343 (ATCC 621H)catalyzes the oxidation of glucose to gluconic acid and subsequently to 5-keto-D-gluconic acid (5-KGA), a precursor of the industrially important L-(+)-tartaric acid. To further increase 5-KGA production in G. oxydans, the mutant strain MF1 was used. In this strain the membrane-bound gluconate-2-dehydrogenase activity, responsible for formation of the undesired by-product 2-keto-D-gluconic acid, is disrupted. Therefore, high amounts of 5-KGA accumulate in the culture medium. G. oxydans MF1 was equipped with plasmids allowing the overexpression of the membrane-bound enzymes involved in 5-KGA formation. Overexpression was confirmed on the transcript and enzymatic level. Furthermore, the resulting strains overproducing the membrane-bound glucose dehydrogenase showed an increased gluconic acid formation, whereas the overproduction of gluconate-5-dehydrogenase resulted in an increase in 5-KGA of up to 230 mM. Therefore, these newly developed recombinant strains provide a basis for further improving the biotransformation process for 5-KGA production.
authors.affiliation: Institut für Biotechnologie 1, Forschungszentrum Jülich GmbH, Jülich, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Merfort
authors.forename: Ute
authors.initials: U
authors.lastname: Herrmann
authors.forename: Seung-Wook
authors.initials: SW
authors.lastname: Ha
authors.forename: Mustafa
authors.initials: M
authors.lastname: Elfari
authors.forename: Stephanie
authors.initials: S
authors.lastname: Bringer-Meyer
authors.forename: Helmut
authors.initials: H
authors.lastname: Görisch
authors.forename: Hermann
authors.initials: H
authors.lastname: Sahm
mesh_terms: D002237:Carbohydrate Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D024861:Genetic Enhancement / Q000379:methods*; D005942:Gluconates / Q000378:metabolism*; D020600:Gluconobacter oxydans / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D010084:Oxidation-Reduction; D015202:Protein Engineering / Q000379:methods
chemical_list: D005942:Gluconates; C093583:5-ketogluconic acid; D002237:Carbohydrate Dehydrogenases; C020577:gluconate 2-dehydrogenase; D005947:Glucose; C030691:gluconic acid