title: Combinatorial modulation of galP and glk gene expression for improved alternative glucose utilization.
abstract: Phosphoenolpyruvate (PEP) is an important precursor for anaerobic production of succinate and malate. Although inactivating PEP/carbohydrate phosphotransferase systems (PTS) could increase PEP supply, the resulting strain had a low glucose utilization rate. In order to improve anaerobic glucose utilization rate for efficient production of succinate and malate, combinatorial modulation of galactose permease (galP) and glucokinase (glk) gene expression was carried out in chromosome of an Escherichia coli strain with inactivated PTS. Libraries of artificial regulatory parts, including promoter and messenger RNA stabilizing region (mRS), were firstly constructed in front of β-galactosidase gene (lacZ) in E. coli chromosome through λ-Red recombination. Most regulatory parts selected from mRS library had constitutive strengths under different cultivation conditions. A convenient one-step recombination method was then used to modulate galP and glk gene expression with different regulatory parts. Glucose utilization rates of strains modulated with either galP or glk all increased, and the rates had a positive relation with expression strength of both genes. Combinatorial modulation had a synergistic effect on glucose utilization rate. The highest rate (1.64 g/L h) was tenfold higher than PTS(-) strain and 39% higher than the wild-type E. coli. These modulated strains could be used for efficient anaerobic production of succinate and malate.
authors.affiliation: Tianjin University of Science & Technology, Tianjin, China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Lu
authors.forename: Jinlei
authors.initials: J
authors.lastname: Tang
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.forename: Xinna
authors.initials: X
authors.lastname: Zhu
authors.forename: Tongcun
authors.initials: T
authors.lastname: Zhang
authors.forename: Xueli
authors.initials: X
authors.lastname: Zhang
mesh_terms: D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005941:Glucokinase / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D009004:Monosaccharide Transport Proteins; C043910:galactose permease; D005941:Glucokinase; D005947:Glucose