Fig. 1

Schematic presentation of sucrose utilization mechanism with gene cassette integrated into E. coli K-12 MG1655 and route of sucrose entering into the central carbon metabolism. a The sucrose integrated cassette csc consists of cscA, cscK, and cscB. CscBK and cscA expression is derived by a bi-directional promoter. b Sucrose utilization starts with uptake of sucrose across the cell membrane by cscB (sucrose permease). Inside the cell sucrose is split into glucose and fructose by cscA (invertase). Glucose and fructose are then phosphorylated by glucokinase (glk) and fructokinase (cscK) respectively. Glucose-6-phosphate can be converted to fructose-6-phosophate by the isomerase (pgi) or enter directly into the pentose phosphate pathway (PP-pathway) or Entner-Doudoroff pathway (ED-pathway); fructose-6-phosphate enters the glycolysis directly