title: Reducing lactate secretion by ldhA Deletion in L-glutamate- producing strain Corynebacterium glutamicum GDK-9.
abstract: L-lactate is one of main byproducts excreted in to the fermentation medium. To improve L-glutamate production and reduce L-lactate accumulation, L-lactate dehydrogenase-encoding gene ldhA was knocked out from L-glutamate producing strain Corynebacterium glutamicum GDK-9, designated GDK-9ΔldhA. GDK-9ΔldhA produced approximately 10.1% more L-glutamate than the GDK-9, and yielded lower levels of such by-products as α-ketoglutarate, L-lactate and L-alanine. Since dissolved oxygen (DO) is one of main factors affecting L-lactate formation during L-glutamate fermentation, we investigated the effect of ldhA deletion from GDK-9 under different DO conditions. Under both oxygen-deficient and high oxygen conditions, L-glutamate production by GDK-9ΔldhA was not higher than that of the GDK-9. However, under micro-aerobic conditions, GDK-9ΔldhA exhibited 11.61% higher L-glutamate and 58.50% lower L-alanine production than GDK-9. Taken together, it is demonstrated that deletion of ldhA can enhance L-glutamate production and lower the unwanted by-products concentration, especially under micro-aerobic conditions.
authors.affiliation: College of Biotechnology Tianjin University of Science and Technology Tianjin P.R. China College of Biotechnology, Tianjin University of Science and Technology, Tianjin, P.R. China. ; Key Laboratory of Industrial Microbiology Education Ministry Tianjin P.R. China Key Laboratory of Industrial Microbiology, Education Ministry, Tianjin, P.R. China.
authors.forename: Dalong
authors.initials: D
authors.lastname: Zhang
authors.affiliation: China Biothech Fermentation Industry Association Beijing P.R. China China Biothech Fermentation Industry Association, Beijing, P.R. China.
authors.forename: Dan
authors.initials: D
authors.lastname: Guan
authors.affiliation: College of Biotechnology Tianjin University of Science and Technology Tianjin P.R. China College of Biotechnology, Tianjin University of Science and Technology, Tianjin, P.R. China. ; Key Laboratory of Industrial Microbiology Education Ministry Tianjin P.R. China Key Laboratory of Industrial Microbiology, Education Ministry, Tianjin, P.R. China.
authors.forename: Jingbo
authors.initials: J
authors.lastname: Liang
authors.affiliation: College of Biotechnology Tianjin University of Science and Technology Tianjin P.R. China College of Biotechnology, Tianjin University of Science and Technology, Tianjin, P.R. China. ; Key Laboratory of Industrial Microbiology Education Ministry Tianjin P.R. China Key Laboratory of Industrial Microbiology, Education Ministry, Tianjin, P.R. China.
authors.forename: Chunqian
authors.initials: C
authors.lastname: Guo
authors.affiliation: College of Biotechnology Tianjin University of Science and Technology Tianjin P.R. China College of Biotechnology, Tianjin University of Science and Technology, Tianjin, P.R. China. ; Key Laboratory of Industrial Microbiology Education Ministry Tianjin P.R. China Key Laboratory of Industrial Microbiology, Education Ministry, Tianjin, P.R. China.
authors.forename: Xixian
authors.initials: X
authors.lastname: Xie
authors.affiliation: College of Biotechnology Tianjin University of Science and Technology Tianjin P.R. China College of Biotechnology, Tianjin University of Science and Technology, Tianjin, P.R. China. ; Key Laboratory of Industrial Microbiology Education Ministry Tianjin P.R. China Key Laboratory of Industrial Microbiology, Education Ministry, Tianjin, P.R. China.
authors.forename: Chenglin
authors.initials: C
authors.lastname: Zhang
authors.affiliation: College of Biotechnology Tianjin University of Science and Technology Tianjin P.R. China College of Biotechnology, Tianjin University of Science and Technology, Tianjin, P.R. China. ; Key Laboratory of Industrial Microbiology Education Ministry Tianjin P.R. China Key Laboratory of Industrial Microbiology, Education Ministry, Tianjin, P.R. China.
authors.forename: Qingyang
authors.initials: Q
authors.lastname: Xu
authors.affiliation: College of Biotechnology Tianjin University of Science and Technology Tianjin P.R. China College of Biotechnology, Tianjin University of Science and Technology, Tianjin, P.R. China. ; Key Laboratory of Industrial Microbiology Education Ministry Tianjin P.R. China Key Laboratory of Industrial Microbiology, Education Ministry, Tianjin, P.R. China.
authors.forename: Ning
authors.initials: N
authors.lastname: Chen
mesh_terms: D048230:Corynebacterium glutamicum / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D018698:Glutamic Acid / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000235:genetics*; D019344:Lactic Acid / Q000378:metabolism*; D060847:Metabolic Engineering; D010100:Oxygen / Q000378:metabolism; D017384:Sequence Deletion
chemical_list: D019344:Lactic Acid; D018698:Glutamic Acid; D007770:L-Lactate Dehydrogenase; D010100:Oxygen
keywords: Corynebacterium glutamicum; L-glutamate; L-lactate dehydrogenase; fermentation; gene knockout