Deletion of pknG Improves the Production of L-Glutamate and GABA in Recombinant Corynbacterium glutamicum

Abstract:

Gama（γ）-aminobutyric acid（GABA），which has a variety of physiological functions，is widely used in food，pharmaceutical and other industries. Two L-glutamate decarboxylase（GAD） genes（gadB1 and gadB2） were co-expressed previously in an L-glutamate producing strain Corynebacterium glutamicum ATCC13032，making the own accumulated L-glutamate be effectively transformed into GABA. To further enhance GABA production，the pknG gene encoding serine/threonine protein kinase PknG was deleted to improve the supply of GABA precursor L-glutamate. Then the co-expression plasmid pJYW-4-gadB1-gadB2 was transformed into pknG deletion strain and ATCC13032，generating the recombinant C. glutamicum strains SNW203 and SNW200. After the strains were fermented in fermenters，the production of both L-glutamate and GABA in SNW203 increased greatly when compared with SNW200. At 72 h of fermentation，GABA production in SNW203 increased to （30.2±0.3） g/L，55.4% higher than that in SNW200 and the total concentration of L-glutamate and GABA reached up to 0.3 mol/L，36.4% higher than that in SNW200. This result indicates that the deletion of pknG improves the biosynthesis of L-glutamate and GABA in recombinant C. glutamicum.