A biosynthetic method and composition for producing
indigo dyes comprising indigotin and
isatin. A tryptophanase (TRP) and a flavin
monooxygenase (FMO) can be produced through a transgenic
organism having carrier encoded tryptophanase and flavin
monooxygenase. The produced tryptophanase and flavin
monooxygenase convert L-
tryptophan into
indigo dyes in the presence of one or more bioactive additives selected from
cysteine, 2-hydroxyindole, or 2-
indoxyl, and the weight ratio of indigotin to
isatin in the dyes is between 1:0.1 to 1:4. The dyes have a
hue of X: 0.1920 to 0.2481, Y: 0.2537 to 0.2019, Z: 0.5543 to 0.5501 in the CIE XYZ
color space definition. Selectable and repeatable
dyeing hues are provided.