Modification of the membrane-bound glucose oxidation system in Gluconobacter oxydans significantly increases gluconate and 5-keto-D-gluconic acid accumulation

• Published in: Biotechnology journal 2006-05, Vol.1 (5), p.556-563
• Main Authors: Merfort, Marcel, Herrmann, Ute, Ha, Seung-Wook, Elfari, Mustafa, Bringer-Meyer, Stephanie, Görisch, Helmut, Sahm, Hermann
• Format: Article
• Language: English
• Subjects: 5-Keto-D-gluconic acid; Carbohydrate Dehydrogenases - genetics; Carbohydrate Dehydrogenases - metabolism; Cell Membrane - metabolism; Genetic Enhancement - methods; Gluconates - metabolism; Gluconobacter; Gluconobacter oxydans; Gluconobacter oxydans - genetics; Gluconobacter oxydans - metabolism; Glucose - metabolism; Oxidation-Reduction; Protein Engineering - methods; Quinoprotein gluconate-5-dehydrogenase; Quinoprotein glucose dehydrogenase
• ISSN: 1860-6768; 1860-7314
• DOI: 10.1002/biot.200600032

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.