Phenol-mediated decolorization and removal of disperse dyes by bitter gourd (Momordica charantia) peroxidase.

Salt-fractionated bitter gourd (Momordica charantia) proteins were employed for the decolorization of disperse dyes in the presence of H2O2. The effect of various experimental conditions such as concentration of enzyme, H2O2, phenol, reaction time, pH and temperature on the decolorization of dyes was investigated. Dyes were recalcitrant to the decolorization catalysed by bitter gourd peroxidase. However, these dyes were decolorized significantly in the presence of a redox mediator, phenol. Bitter gourd peroxidase (0.215 U/mL) could decolorize about 60% of Disperse Red 17 in the presence of 0.2 mM phenol, whereas Disperse Brown 1 was decolorized by only 40% even in the presence of 0.4 mM phenol. Maximum decolorization of dyes was achieved in the presence of 0.75 mM H2O2 in a buffer ofpH 3.0 and 40 degrees C within 30 min. The K(m) values obtained were 0.625 mg/(L x h) and 2.5 mg/(L x h) for Disperse Red 17 and Disperse Brown 1, respectively. In all the experiments, Disperse Brown 1 was found to be more recalcitrant to decolorization catalysed by bitter gourd peroxidise, as compared to Disperse Red 17.