Mechanistic study of degradation of basic violet 3 by Citrus limon peroxidase and phytotoxicity assessment of its degradation products

The current study evaluates the potential of partially purified Citrus limon (lemon) peroxidase in the decolorization of a common synthetic triphenylmethane class dye; basic violet 3. Some important process parameters were optimized by OFAT methodology. Along with this, the effect of metal ions and mediators on the process of decolorization was also evaluated. The maximum decolorization (96.34%) of 7.5 mg/L dye was achieved at 42 U/mL of enzyme dose, 0.25 mM of H2O2 and 0.5 mM of p-coumaric acid. The pH, temperature and time for maximum decolorization were recorded to be 4.5, 45 degrees C, and 5 min, respectively. The presence of metal ions did not exert any drastic influence on the process of decolorization, ensuring it suitable for industrial applications. The optimization and interactive effect of pH, enzyme dose, and dye concentration for maximum decolorization was also investigated by RSM through central composite design matrix. UPLC/MS analyses were performed to identify the degradation products. As a result a mechanistic pathway for degradation of basic violet 3 was proposed. It was also found that degraded products of basic violet 3 showed less phytotoxicity than the dye itself, using Zea mays as test organism. (C) 2014 Elsevier B.V. All rights reserved.