Isolation of a New Root Growth-stimulating Substance from a Fungus

In the last few decades, enzymatic production of 3,4-dihydroxyphenyl-L-alanine (L-dopa) using tyrosine phenol-lyase (Tpl) has been industrialized. This method has an intrinsic problem of tyrosine contamination because Tpl is synthesized under tyrosine-induced conditions. Herein, we constructed a hyper-L-dopa-producing strain by exploiting a mutant TyrR, an activator of tpl. The highest productivity was obtained for the strain grown under non-induced conditions. It was 30-fold higher than that obtained for tyrosine-induced wild-type cells.