title: L-valine production with pyruvate dehydrogenase complex-deficient Corynebacterium glutamicum.
abstract: Corynebacterium glutamicum was engineered for the production of L-valine from glucose by deletion of the aceE gene encoding the E1p enzyme of the pyruvate dehydrogenase complex and additional overexpression of the ilvBNCE genes encoding the L-valine biosynthetic enzymes acetohydroxyacid synthase, isomeroreductase, and transaminase B. In the absence of cellular growth, C. glutamicum DeltaaceE showed a relatively high intracellular concentration of pyruvate (25.9 mM) and produced significant amounts of pyruvate, L-alanine, and L-valine from glucose as the sole carbon source. Lactate or acetate was not formed. Plasmid-bound overexpression of ilvBNCE in C. glutamicum DeltaaceE resulted in an approximately 10-fold-lower intracellular pyruvate concentration (2.3 mM) and a shift of the extracellular product pattern from pyruvate and L-alanine towards L-valine. In fed-batch fermentations at high cell densities and an excess of glucose, C. glutamicum DeltaaceE(pJC4ilvBNCE) produced up to 210 mM L-valine with a volumetric productivity of 10.0 mM h(-1) (1.17 g l(-1) h(-1)) and a maximum yield of about 0.6 mol per mol (0.4 g per g) of glucose.
authors.affiliation: Institute of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany.
authors.forename: Bastian
authors.initials: B
authors.lastname: Blombach
authors.forename: Mark E
authors.initials: ME
authors.lastname: Schreiner
authors.forename: Jirí
authors.initials: J
authors.lastname: Holátko
authors.forename: Tobias
authors.initials: T
authors.lastname: Bartek
authors.forename: Marco
authors.initials: M
authors.lastname: Oldiges
authors.forename: Bernhard J
authors.initials: BJ
authors.lastname: Eikmanns
mesh_terms: D000409:Alanine / Q000096:biosynthesis; D048230:Corynebacterium glutamicum / Q000378:metabolism*; D005285:Fermentation; D007532:Isoleucine / Q000096:biosynthesis; D008239:Lysine / Q000096:biosynthesis; D011768:Pyruvate Dehydrogenase Complex / Q000235:genetics / Q000502:physiology*; D019289:Pyruvic Acid / Q000378:metabolism; D014633:Valine / Q000096:biosynthesis*
chemical_list: D011768:Pyruvate Dehydrogenase Complex; D007532:Isoleucine; D019289:Pyruvic Acid; D014633:Valine; D008239:Lysine; D000409:Alanine