Improved Lactose Utilization by Overexpression β-Galactosidase and Lactose Permease in Klebsiella pneumoniae

摘要

As an important bio-based chemical product, 2,3-butanediol has a wide range of applications in many fields, such as chemical, fuel, food, and aerospace. Cheese whey powder (CWP), an inexpensive, available, and abundant material, is considered to be an ideal substrate for 2,3-BD fermentation. To improve 2,3-butanediol production, the previous studies mainly focus on the metabolic pathway from pyruvate to 2,3-butanediol or the metabolic pathway of by-products, but studies about improving lactose utilization rate are rarely reported. In the present study, adding exogenous β-galactosidase was proved to favor the lactose utilization and lactose utilization might be the limiting step of lactose fermentation to 2,3-butanediol. ElacY (encoding lactose permease of Escherichia coli) and bgaB (encoding β-galactosidase of K. pneumonia) were overexpressed in K. pneumonia CICC10781. Of the two genes, only overexpression of ElacY promoted lactose utilization of CICC 10781, and meanwhile the 2,3-butanediol generation capacity was not affected.