Effects of oxaloacetate anaplerotic reaction mediated by phosphoenolpyruvate carboxylase (PEPC) and phosphoenolpyruvate carboxykinase (PCK) on amino acid etabolism of Corynebacterium glutamicum V1

Abstract:

[Objective] Corynebacterium glutamicum is the main industry strain for production of amino acids, to explore the effects of oxaloacetate anaplerotic reaction mediated by phosphoenolpyruvate carboxylase (PEPC) and phosphoenolpyruvate carboxykinase (PCK) on physiological characteristics and amino acid metabolism, the valine producing strain Corynebacterium glutamicum V1 was studied. [Methods] Overexpressing of pepc encoding PEPC and pck encoding PCK in Corynebacterium glutamicum V1 by means of genetic engineering, the changes of key enzyme activities, fermentation characteristics and main amino acids accumulation were discussed compared with the original strain. [Results] Two recombinant strains V1-pepc (enhanced oxaloacetate anaplerotic pathway) and V1-pck (weakened oxaloacetate anaplerotic pathway) were constructed, both the growth trends were delayed, the total biomass and the consumption of sugar and ammonium basically unchanged; Overexpression of pck, the activity of PCK has 22.8% increased, the yields of alanine, valine, glutamic and arginine were increased by 11.8%, 17.2%, 27.8% and 19.5% respectively; Over expression of pepc, the activity of PEPC increased by 27.5%, while the activity of PC decreased 12.9%, the overall flow of aspartic and glutamic-family amino acids changes little, while the flow of alanine-family reduced by 14.7%. [Conclusion] Alanine-family amino acids are greatly influenced by this pathway while aspartate-family not.