Modification of the membrane-bound glucose oxidation system in Gluconobacter oxydans significantly increases gluconate and 5-keto-D-gluconic acid accumulation.
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.
Merfort
Marcel
M
Institut für Biotechnologie 1, Forschungszentrum Jülich GmbH, Jülich, Germany.
Herrmann
Ute
U
Ha
Seung-Wook
SW
Elfari
Mustafa
M
Bringer-Meyer
Stephanie
S
Görisch
Helmut
H
Sahm
Hermann
H
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
D005942:Gluconates; C093583:5-ketogluconic acid; D002237:Carbohydrate Dehydrogenases; C020577:gluconate 2-dehydrogenase; D005947:Glucose; C030691:gluconic acid