[Transformation of phosphotransferase system in Escherichia coli]

We constructed several recombinant Escherichia coli strains to transform phosphoenolpyruvate: carbohydrate phosphotransferase system (PTS system) and compared the characteristics of growth and metabolism of the mutants. We knocked-out the key genes ptsI and ptsG in PTS system by using Red homologous recombination in E. coli and meanwhile we also knocked-in the glucose facilitator gene glf from Zymomonas mobilis in the E. coli chromosome. Recombinant E. coli strains were constructed and the effects of cell growth, glucose consumption and acetic acid accumulation were also evaluated in all recombinant strains. The deletion of gene ptsG and ptsI inactivated some PTS system functions and inhibited the growth ability of the cell. Expressing the gene glf can help recombinant E. coli strains re-absorb the glucose through Glf-Glk (glucose facilitator-glucokinase) pathway as it can use ATP to phosphorylate glucose and transport into cell. This pathway can improve the availability of glucose and also reduce the accumulation of acetic acid; it can also broaden the carbon flux in the metabolism pathway.