Optimal Ratio of Carbon Flux between Glycolysis and the Pentose Phosphate Pathway for Amino Acid Accumulation in Corynebacterium glutamicum

Glucose is metabolized through central metabolic pathways such as glycolysis and the pentose phosphate pathway (PPP) to synthesize downstream metabolites including amino acids. However, how the split ratio of carbon flux between glycolysis and PPP specifically affects the formation of downstream metabolites remains largely unclear. Here, we conducted a comprehensive metabolomic analysis to investigate the effect of the split ratio between glycolysis and the PPP on the intracellular concentration of amino acids and their derivatives in Corynebacterium glutamicum. The split ratio was varied by exchanging the promoter of a gene encoding glucose 6-phosphate isomerase (PGI). The ratio was correlated with the pgi transcription level and the enzyme activity. Concentrations of threonine and lysine-derivative 1,5-diaminopentane increased with an increase of the split ratio into the PPP. In contrast, concentrations of alanine, leucine, and valine were increased with an increase of the split ratio into glycolysis. These results could provide a new engineering target for improving the production of the amino acids and the derivatives.