Integrated transcriptomic and metabolomic analyses uncover novel genetic targets for enhanced l-tryptophan production...

Corynebacterium glutamicum is a promising microbial chassis for the industrial production of l-tryptophan, an essential amino acid with diverse applications and high market value. In our previous work, we constructed an l-tryptophan-overproducing C. glutamicum strain, TR26, through multiple rounds of rational metabolic engineering. Here, comparative transcriptomic and metabolomic analyses were conducted between TR26 and its progenitor MB001 to elucidate the underlying molecular mechanisms and identify potential bottlenecks for l-tryptophan production in TR26. Based on the differentially expressed genes identified, systematic gene overexpression and knockdown experiments led to the identification of two novel genetic targets, glnK and sugR. Specifically, the repression of glnK and overexpression of sugR in TR26 increased the l-tryptophan titer by 10.3 % and 16.5 % in fed-batch fermentation, and the yield by 7.2 % and 20.2 %, respectively. Further transcription profiling and intracellular metabolite analysis indicated that these improvements were associated with altered nitrogen metabolism, more efficient allocation of cellular resources, and enhanced supply of phosphoenolpyruvate (PEP), a key precursor in aromatic amino acid biosynthesis. This study expands our understanding of the regulation mechanisms governing l-tryptophan synthesis in C. glutamicum and provides valuable insights for further optimization of industrial cell factories.