High-yield 5-keto-D-gluconic acid formation is mediated by soluble and membrane-bound gluconate-5-dehydrogenases of Gluconobacter oxydans.
Gluconobacter oxydans DSM 2343 is known to catalyze the oxidation of glucose to gluconic acid, and subsequently, to 2-keto-D-gluconic acid (2-KGA) and 5-keto-D-gluconic acid (5-KGA), by membrane-bound and soluble dehydrogenases. In G. oxydans MF1, in which the membrane-bound gluconate-2-dehydrogenase complex was inactivated, formation of the undesired 2-KGA was absent. This mutant strain uniquely accumulates high amounts of 5-KGA in the culture medium. To increase the production rate of 5-KGA, which can be converted to industrially important L-(+)-tartaric acid, we equipped G. oxydans MF1 with plasmids allowing the overproduction of the soluble and the membrane-bound 5-KGA-forming enzyme. Whereas the overproduction of the soluble gluconate:NADP 5-oxidoreductase resulted in the accumulation of up to 200 mM 5-KGA, the detected 5-KGA accumulation was even higher when the gene coding for the membrane-bound gluconate-5-dehydrogenase was overexpressed (240 to 295 mM 5-KGA). These results provide a basis for designing a biotransformation process for the conversion of glucose to 5-KGA using the membrane-bound as well as the soluble enzyme system.
Merfort
Marcel
M
Institut für Biotechnologie 1, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
Herrmann
Ute
U
Bringer-Meyer
Stephanie
S
Sahm
Hermann
H
D000085:Acetates / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D001709:Biotechnology / Q000379:methods*; D002244:Carbon / Q000737:chemistry; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005942:Gluconates / Q000737:chemistry* / Q000378:metabolism; D020600:Gluconobacter oxydans / Q000201:enzymology*; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010088:Oxidoreductases / Q000737:chemistry / Q000502:physiology*; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D013644:Tartrates / Q000737:chemistry; D013997:Time Factors
D000085:Acetates; D001426:Bacterial Proteins; D005942:Gluconates; D013644:Tartrates; D002244:Carbon; C093583:5-ketogluconic acid; D010088:Oxidoreductases; C093584:gluconate 5-dehydrogenase; D005947:Glucose; C030691:gluconic acid; D010100:Oxygen; C029768:tartaric acid