The purpose of this work is to investigate the decoloration and bleaching of various kinds of dyes in aqueous solutions and on fabrics with one of the oxidoreductases, laccase. The twenty-two water-soluble dyes of azo, anthraquinone, acridine, triphenylmethane, and indigo types were employed. In addition bleaching effect of denim cotton fabrics dyed with indigo was also examined. The two laccase preparations from Trametes villosa and Trametes sp. were utilized. The rate of enzyme-catalyzed

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... ions on the dyes was measured spectrophotometrically. The Michaelis-Menten constant and catalytic efficiency of the enzyme were evaluated by using the Michaelis-Menten equation. A redox mediator in combination with the laccases was tried to enhance the enzyme activity. The orders of catalytic efficiency were 10 2 10 5 and the difference among the dyes examined showed to be ca. 600 times. One of the enzymes employed was found to exhibit rapid degradation rate for anthraquinone dyes specifically. Comparing with the values of Michaelis-Menten constant of the dyes, the indigo type dye revealed the lower value, indicating higher affinity toward the enzyme. The treatment of indigo dyed fabrics with the laccase was found to bleach strongly the surface of fabrics by the addition of mediator.