Alleviating carbon catabolite repression in the chassis microorganism to enhance fermentation yield of 2,3-butanediol based on galP overexpression
To enhance capability of Klebsiella pneumoniae in utilizing mixed carbon sources and to address the deficiencies in glucose utilization due to ptsG gene deletion,the genetic engineering to overexpress galactose permease gene(galP)was employed this study.As a result,a strain capable of high 2,3-butanediol(2,3-BD)production was developed.Successful cloning and overexpression of galP in the K.pneumoniae HD79-N(△ptsG)strain led to the engineered strain K.pneumoniae HD79-A.It exhibited reduced carbon catabolite repression(CCR)and the ability to simultaneously utilize glucose and xylose,achieving a final yield of 13.15±0.66 g·L-1 of 2,3-BD.Compared to the chassis microorganism,the yield of 2,3-BD increased by 34.05％,glucose utilization rate(1.104 g·L-1·h-1)improved by 105.59％,and total sugar consumption(70.76 g·L-1)rose by 9.60％.Additionally,K.pneumoniae HD79-A demonstrated that production intensity,alcohol conversion rate,and cell-specific conversion efficiency were 1.34-fold,1.22-fold,and 1.04-fold greater than those of K.pneumoniae HD79-N,respectively.This study confirmed that overexpressing the galP can effectively dual-regulate K.pneumoniae HD79-N(△ptsG),providing a theoretical basis for the efficient production of 2,3-BD using functional engineered strains under mixed carbon source conditions.
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