Comparison of individual component deletions in a glucose-specific phosphotransferase system revealed their different applications

Abstract

The phosphoenolpyruvate-dependent glucose-specific phosphotransferase system (PTS ^Glc) is the main glucose uptake pathway in Escherichia coli that affects both substrate assimilation and metabolism leading to the product formation. In this study, the effect of single PTS ^Glc mutation on cell growth and substrate consumption was investigated by knocking out the genes involved in the phosphotransfer cascade of the PTS ^Glc. In addition, the distribution of the metabolites of mutants was analyzed. Each mutant was confirmed to have different adaptability in the presence of both glucose and xylose with different ratios, and a substrate mixture with high xylose content can be completely consumed in short time when the ptsI mutant is employed. Finally, ptsH deletion was for the first time applied for succinate production due to its well performance under anaerobic condition. Strain YL104H, in which ptsH was deleted, exhibited considerably increased succinate yield under both aerobic and anaerobic conditions. The succinate titer and overall productivity reached 511.11 mM and 1.01 g/L/h after 60 h during the whole-phase fermentation in a mineral salt medium. The present results demonstrated the glucose and xylose co-utilization efficiency and the product yield and productivity can be significantly improved if a suitable PTS ^Glc deletion mutant was selected.