The enzymatic decolorization of 13 synthetic dyes with azo- and anthraquinone-based chemical structures
using the purified laccase from Paraconiothyrium variabile was assessed in the presence and
absence of 1-hydroxybenzotriazole (HBT) as a laccase mediator. The highest decolorization percentage
was found for Acid Red 18 (97%) followed by Direct Red 81 (68.3%), Reactive Yellow 15 (60.2%), and
Disperse Blue 56 (58%) after 15 min of incubation in the presence of 0.1 U mL1 of the enzyme. The use of
the laccase-HBT system increased decolorization percentage of Reactive Orange 16, Reactive Black 5,
Direct Blue 71, Disperse Red 177, and Acid Yellow 36, while other chemical dyes were not affected by an
increase of the HBT concentration. The kinetic parameters of the purified laccase for each textile dye were
also calculated. A microtoxicity study with respect to the inhibition of bacterial growth showed a
decrease in toxicity of the laccase-treated dye solution.