Advances in the microbial biosynthesis of ʟ-tryptophan and its derivatives

l-Tryptophan, an essential aromatic amino acid, is widely used in the pharmaceutical and food industries owing to its distinctive indole ring structure, which is unique among proteinogenic amino acids. Moreover, structurally modified derivatives of l-tryptophan have drawn considerable attention from researchers due to their improved functional properties. Recently, microbial synthesis has emerged as an environmentally sustainable approach for producing l-tryptophan and its derivatives. While significant progress has been made in optimizing biosynthetic pathways, several key bottlenecks remain. This review surveys recent optimizations that increase microbial l-tryptophan titers and the resulting engineered strains for their high-value derivatives. Moreover, transformative opportunities for advancing l-tryptophan derivatives production, offered by the rapid evolution of synthetic biology, are discussed.