Gamma-aminobutyric acid is an important nonprotein amino acid and has been extensively applied in pharmaceuticals,livestock,food additives,and so on.It is important to develop Corynebacterium glutamicum strains that c...Gamma-aminobutyric acid is an important nonprotein amino acid and has been extensively applied in pharmaceuticals,livestock,food additives,and so on.It is important to develop Corynebacterium glutamicum strains that can efciently produce gamma-aminobutyric acid from glucose.In this study,production of gamma-aminobutyric acid in C.glutamicum CGY700 was improved by construction of CO_(2) anaplerotic reaction and overexpression of citrate synthase.The co-expression of ppc encoding phosphoenolpyruvate carboxylase and gltA encoding citrate synthase was constructed and optimized in the chromosome to compensate carbon loss and conquer metabolic bottleneck.The expression of ppc and gltA were controlled by promoters P_(tac) and P_(tacM),and the optimal mode of P_(tacM-ppc)-P_(tac)-gltA was determined.Simultaneously,the genes pknG encoding serine/threonine protein kinase G and ldh encoding l-lactate dehydrogenase were deleted,and glnA2 encoding glutamine synthase was overexpressed in the chromosome.The fnal strain CGY-PG-304 constructed in this study could produce 41.17 g/L gamma-aminobutyric acid in shake fask cultivation and 58.33 g/L gamma-aminobutyric acid via FedBatch fermentation with a yield of 0.30 g/g glucose.CGY-PG-304 was constructed by genome editing;therefore,it is stable and not necessary to add any antibiotics and inducer during fermentation.展开更多
基金Publication costs are funded by the National Key Research and Development Program of China(2021YFC2100900)the Key Technology Project of Inner Mongolia Autonomous Region,China(2019GG302).
文摘Gamma-aminobutyric acid is an important nonprotein amino acid and has been extensively applied in pharmaceuticals,livestock,food additives,and so on.It is important to develop Corynebacterium glutamicum strains that can efciently produce gamma-aminobutyric acid from glucose.In this study,production of gamma-aminobutyric acid in C.glutamicum CGY700 was improved by construction of CO_(2) anaplerotic reaction and overexpression of citrate synthase.The co-expression of ppc encoding phosphoenolpyruvate carboxylase and gltA encoding citrate synthase was constructed and optimized in the chromosome to compensate carbon loss and conquer metabolic bottleneck.The expression of ppc and gltA were controlled by promoters P_(tac) and P_(tacM),and the optimal mode of P_(tacM-ppc)-P_(tac)-gltA was determined.Simultaneously,the genes pknG encoding serine/threonine protein kinase G and ldh encoding l-lactate dehydrogenase were deleted,and glnA2 encoding glutamine synthase was overexpressed in the chromosome.The fnal strain CGY-PG-304 constructed in this study could produce 41.17 g/L gamma-aminobutyric acid in shake fask cultivation and 58.33 g/L gamma-aminobutyric acid via FedBatch fermentation with a yield of 0.30 g/g glucose.CGY-PG-304 was constructed by genome editing;therefore,it is stable and not necessary to add any antibiotics and inducer during fermentation.
