Potential of peroxidase enzyme from Trichosanthes diocia to mediate disperse dye decolorization in conjunction with redox mediators

Disperse dyes are frequently used worldwide for dyeing polyester, nylon, cellulose acetate and acrylic fibers. The highly variable and complex chemical structure of the dyes makes them difficult to remove using conventional wastewater treatment systems. Redox mediated enzymatic catalysis has wide applications including degradation of polycyclic compounds, phenols, aromatic amines, biphenyls, pesticides, insecticides etc. We investigated the effect of Trichosanthes diocia peroxidase along with redox mediators on decolorization of water insoluble disperse dyes; Disperse Red 19 and Disperse Black 9. Nine different redox mediators; bromophenol, 2,4-dichlorophenol, guaiacol, 1-hydroxybenzotriazole, m-cresol, quinol, syringaldehyde, vanillin and violuric acid were evaluated. Results indicated that among the chosen mediators, 1-hydroxybenzotriazole (HOBT) was most effective for decolorization. At a concentration of 0.45 U mL−1 the peroxidase could decolorize Disperse Red 19 to a maximum of 79% with O.2 mM 1-hydroxybenzotriazole whereas Disperse Black 9 decolorized upto 60% with 0.5 mM 1-hydroxybenzotriazole. The time, pH and temperature at which maximum decolorization were recorded was 60 min, 4 and 42 °C. Data were analyzed by one-way ANOVA and Mann Whitney test. The study suggests that peroxidase from T. diocia could be a cheap, easy, effective source and along with redox mediators be used to treat recalcitrant synthetic dyes.