synthesis |
engineering of the wild type of Corynebacterium glutamicum for the growth-decoupled production of 2-ketoisovalerate from glucose by deletion of the aceE gene encoding the E1p subunit of the pyruvate dehydrogenase complex, deletion of the transaminase B gene ilvE, and additional overexpression of the ilvBNCD genes, encoding the L-valine biosynthetic enzymes acetohydroxyacid synthase (AHAS), acetohydroxyacid isomeroreductase, and dihydroxyacid dehydratase. 2-Ketoisovalerate production is further improved by deletion of the pyruvate:quinone oxidoreductase gene pqo. In fed-batch fermentations at high cell densities, the newly constructed strains produce up to 188 mM (21.8 g/liter) 2-ketoisovalerate and showd a product yield of about 0.47 mol per mol (0.3 g/g) of glucose and a volumetric productivity of about 4.6 mM (0.53 g/liter) 2-ketoisovalerate per h in the overall production phase |
Corynebacterium glutamicum |