Indigo degradation with laccases from Polyporus sp. and Sclerotium rolfsii

We have investigated the potential of fungal laccases from Polyporus sp. and Sclerotium rolfsii to degrade insoluble indigo. Evidence shows that both laccases are able to oxidize insoluble indigo to give isatin (indole-2,3-dione), which further degrades to anthranilic acid (2-aminobenzoic acid). Adsorption studies show that the laccase from Polyporus sp. has a higher affinity for indigo than the laccase of Sclerotium rolfsii. The particle size of indigo agglomerates is influenced by the origin of the laccase preparation and the incubation time: The potential of laccases to modify indigo stained fabrics is assessed. Treatment of indigo dyed fabrics with laccase prevents indigo backstaining, and Polyporus sp. appears to be more effective for reducing backstaining.