Biosynthesis of the Textile Dye Indigo by a Recombinant Bacterium

The biosynthesis of indigo by microorganisms can be manipulated through molecular biological techniques that alter the stability, activity, and final product of biosynthetic pathways in the cell. Transformed microorganisms may synthesize indigo at commercially significant rates and yields from glucose and other simple precursors. A cluster of five genes comprising the tryptophan biosynthetic operon and containing an altered trpB gene causes a host cell to synthesize high levels of indole from glucose after introduction into Escherichia coli. The addition of four genes encoding the naphthalene dioxygenase enzyme system enables the organism to rapidly oxidize indole to indigo, which is secreted into the fermentation medium. The synthesis by fermentation of indigo may be a cost-competitive approach if optimization and scale-up efforts are successful.