Production of aromatic amino acids and their derivatives by Escherichia coli and Corynebacterium glutamicum

Demand for aromatic amino acids (AAAs), such as L-phenylalanine, L-tyrosine, and L-tryptophan, has been increasing as they are used in animal feed and as precursors in the synthesis of industrial and pharmaceutical compounds. These AAAs are biosynthesized through the shikimate pathway in microorganisms and plants, and the reactions in the AAA biosynthesis pathways are strictly regulated at the levels of both gene expression and enzyme activity. Various attempts have been made to produce AAAs and their derivatives using microbial cells and to optimize production. In this review, we summarize the metabolic pathways involved in the biosynthesis of AAAs and their regulation and review recent research on AAA production using industrial bacteria, such as Escherichia coli and Corynebacterium glutamicum. Studies on fermentative production of AAA derivatives, including L-3,4-dihydroxyphenylalanine, tyrosol, and 3-hydroxytyrosol, are also discussed.