title: Enhancing the supply of oxaloacetate for L-glutamate production by pyc overexpression in different Corynebacterium glutamicum.
abstract: During L-glutamate production, phosphoenolpyruvate carboxylase and pyruvate carboxylase (PCx) play important roles in supplying oxaloacetate to the tricarboxylic acid cycle. To explore the significance of PCx for L-glutamate overproduction, the pyc gene encoding PCx was amplified in Corynebacterium glutamicum GDK-9 triggered by biotin limitation and CN1021 triggered by a temperature shock, respectively. In the fed-batch cultures, GDK-9pXMJ19pyc exhibited 7.4 % lower L-alanine excretion and no improved L-glutamate production. In contrast, CN1021pXMJ19pyc finally exhibited 13 % lower L-alanine excretion and identical L-glutamate production, however, 8.5 % higher L-glutamate production was detected during a short period of the fermentation. It was indicated that pyc overexpression in L-glutamate producer strains, especially CN1021, increased the supply of oxaloacetate for L-glutamate synthesis and decreased byproduct excretion at the pyruvate node.
authors.affiliation: National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin, 300457, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Guo
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Xixian
authors.initials: X
authors.lastname: Xie
authors.forename: Qingyang
authors.initials: Q
authors.lastname: Xu
authors.forename: Chenglin
authors.initials: C
authors.lastname: Zhang
authors.forename: Ning
authors.initials: N
authors.lastname: Chen
mesh_terms: D048230:Corynebacterium glutamicum / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D018698:Glutamic Acid / Q000378:metabolism*; D062907:Oxaloacetic Acid / Q000378:metabolism*; D011766:Pyruvate Carboxylase / Q000235:genetics / Q000378:metabolism*
chemical_list: D062907:Oxaloacetic Acid; D018698:Glutamic Acid; D011766:Pyruvate Carboxylase