Decolorization Assay of the Anthraquinone Dye Acid Blue 25 by Trichoderma asperellum LBKURCC1 Crude Laccase Extracts
Abstract One major concern of the textile industry waste is the health hazard imposed by textile dye waste effluents. Anthraquinone dyes are the second largest group of dyes produced and used annually worldwide, that is difficult to degrade naturally. Biological methods using enzymes for waste treatment is gaining popularity due to its eco-friendliness. Laccase is an enzyme with potential to degrade textile dyes, due to its wide ability to oxidize a wide range of substrates. The aim of this study was to evaluate the ability of T. asperellum LBKURCC1 laccase crude extract to decolorize the anthraquinone anionic dye Acid Blue 25 (AB25). A solution of 50 ppm AB25, pH 5.5, was treated with T. asperellum LBKURCC1 laccase crude extract and incubated at room temperature. Absorbance of the solution at 603 nm was measured daily and compared to buffer and heat denatured enzyme controls. No decolorization of AB25 was observed up to 6 days incubation in the enzyme treated samples, as well as the controls. Addition of 0.1 to 5 mM of 1-hydroxybenzotriazole hydrate (HBT) to the decolorization assay did not succeed in mediating the redox reaction of AB25 oxidation by the T. asperellum LBKURCC1 laccase.