Oxidation characteristics and degradation potential of a dye-decolorizing peroxidase from Bacillus amyloliquefaciens for crystal violet dye

In the current work, studies were conducted for understanding oxidation characteristics and biodegradation potential of a dye-decolorizing peroxidases from Bacillus amyloliquefaciens (BaDyP) for triphenylmethane dye crystal violet (CV). Recombinant BaDyP from Bacillus amyloliquefaciens MN-13 exhibits a broad substrates profile. It can oxidize ABTS, veratryl alcohol, Mn 2+ , azo dye reactive black 5, anthraquinone dye reactive blue 19, but cannot oxidize guaiacol. The maximum BaDyP activity against ABTS was obtained at 30 ℃ and pH 4.0. When CV was treated by BaDyP for 72 h, the degradation percentage of 63.0 % was observed. UV–vis spectra and HPLC/MS analysis indicated that CV degradation occurred via N -demethylation and cleavage of conjugated chromophore structure. The identified degradation products included stepwise N -demethylated intermediates during the N -demethylation of CV and, 4-( N -methylamino)-4′-( N ’-methylamino) benzophenone and 4-( N -methylamino)-4′-amino benzophenone after cleavage of conjugated chromophore structure. Based on these data, a hypothetic mechanism of CV degradation mediated by BaDyP was proposed in this study. Finally, it is worth to be noted that BaDyP possessed high decolorization efficiency (72.3 % removal ADMI) for actual dye effluent. These results demonstrated that BaDyP might be used as an efficient biocatalyst for the enzymatic pretreatment of dyes in wastewater.