The decolorization and detoxification of textile dyes by fungal laccase immobilized on porous glass beads
were evaluated. Anthraquinone (Reactive blue 19 and Dispersed blue 3) and indigoid (Acid blue 74) dyes
were degraded more rapidly than the azo dyes (Acid red 27 and Reactive black 5). There was no dye sorption
to the enzyme bed when decolorization rates were high (>12 lM dye/U-h) but at moderate rates (8
to >0.06 lM/U-h), there was a transient color which disappeared upon prolonged exposure. With Reactive
black 5, permanent adsorption occurred most likely because laccase had been totally inactivated. Although
laccase treatment was more efficient at decolorizing the anthraquinone dyes, their toxicity (as determined
by the Microtox assay) increased while the less efficiently decolorized solutions of azo and indigoid dyes
became less toxic. These results demonstrate the potential and limitations of using immobilized laccase to
enzymatically decolorize a range of different dye classes and reduce dye toxicity in a single step