title: Efficient production of α-ketoglutarate in the gdh deleted Corynebacterium glutamicum by novel double-phase pH and biotin control strategy.
abstract: Production of L-glutamate using a biotin-deficient strain of Corynebacterium glutamicum has a long history. The process is achieved by controlling biotin at suboptimal dose in the initial fermentation medium, meanwhile feeding NH4OH to adjust pH so that α-ketoglutarate (α-KG) can be converted to L-glutamate. In this study, we deleted glutamate dehydrogenase (gdh1 and gdh2) of C. glutamicum GKG-047, an L-glutamate overproducing strain, to produce α-KG that is the direct precursor of L-glutamate. Based on the method of L-glutamate fermentation, we developed a novel double-phase pH and biotin control strategy for α-KG production. Specifically, NH4OH was added to adjust the pH at the bacterial growth stage and NaOH was used when the cells began to produce acid; besides adding an appropriate amount of biotin in the initial medium, certain amount of additional biotin was supplemented at the middle stage of fermentation to maintain a high cell viability and promote the carbon fixation to the flux of α-KG production. Under this control strategy, 45.6 g/L α-KG accumulated after 30-h fermentation in a 7.5-L fermentor and the productivity and yield achieved were 1.52 g/L/h and 0.42 g/g, respectively.
authors.affiliation: College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China.|National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin, 300457, China.|Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, China.
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Li
authors.affiliation: College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China.
authors.forename: Lanchao
authors.initials: L
authors.lastname: Sun
authors.affiliation: College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Feng
authors.affiliation: College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China.
authors.forename: Ruifang
authors.initials: R
authors.lastname: Wu
authors.affiliation: College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China.|National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin, 300457, China.|Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, China.
authors.forename: Qingyang
authors.initials: Q
authors.lastname: Xu
authors.affiliation: College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China.|National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin, 300457, China.|Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, China.
authors.forename: Chenglin
authors.initials: C
authors.lastname: Zhang
authors.affiliation: College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China. ningch@tust.edu.cn.|National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin, 300457, China. ningch@tust.edu.cn.|Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, China. ningch@tust.edu.cn.
authors.forename: Ning
authors.initials: N
authors.lastname: Chen
authors.affiliation: College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China. xixianxie@tust.edu.cn.|National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin, 300457, China. xixianxie@tust.edu.cn.|Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, China. xixianxie@tust.edu.cn.
authors.forename: Xixian
authors.initials: X
authors.lastname: Xie
mesh_terms: D001710:Biotin / Q000378:metabolism*; D048230:Corynebacterium glutamicum / Q000201:enzymology / Q000378:metabolism*; D003470:Culture Media; D005285:Fermentation; D005969:Glutamate Dehydrogenase / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007656:Ketoglutaric Acids / Q000378:metabolism*
chemical_list: D003470:Culture Media; D007656:Ketoglutaric Acids; D001710:Biotin; D005969:Glutamate Dehydrogenase
keywords: Biotin; Corynebacterium glutamicum; L-Glutamate; pH; α-Ketoglutarate