Triphenylmethane dyes are commonly used in dyeing and printing, but such dyes are recalcitrant to degradation and thus biodegradation of dye compounds has received increasing attention. Here, a recombinant bacterial laccase, CotA, from Bacillus amyloliquefaciens MN-13 was expressed in Escherichia coli BL21(DE3) and used as a biocatalyst to degrade crystal violet (CV). The recombinant CotA remained stable at temperatures in the range 30–40 °C and retained 44–100% enzyme activity at pH 4.5–8.0. The CotA exhibited high activities for decolorization of CV and, after 72 h of incubation, CotA decolorized 70.98% of CV at pH 5.0 and 30 °C. In the UV–visible spectra of CV solution treated by CotA, the full wavelength scan indicated that the chromophore of the triphenylmethane structure of CV was destroyed and CV was degraded into small-molecule aromatic compounds. The main degradation compounds of CV were identified as bis[4-(dimethylamino) phenyl] methanone and its N-demethylation derivative by HPLC/MS/MS. Based on these data, a hypothetical degradation pathway of CV by CotA, including N-demethylation and cleavage of the chromophore structure initiated by radicals, is proposed.

三苯甲烷染料通常用于染色和印刷，但是这类染料难以降解，因此染料化合物的生物降解受到越来越多的关注。在这里，在大肠杆菌中表达了来自解淀粉芽孢杆菌MN-13的重组细菌漆酶CotA。BL21（DE3），用作降解紫水晶（CV）的生物催化剂。重组CotA在30–40°C的温度范围内保持稳定，并在pH 4.5–8.0的条件下保留44-100％的酶活性。CotA表现出高的CV脱色活性，孵育72小时后，CotA在pH 5.0和30°C下使CV脱色了70.98％。在CotA处理的CV溶液的紫外可见光谱中，全波长扫描表明CV的三苯基甲烷结构的发色团被破坏，CV降解为小分子芳族化合物。CV的主要降解化合物通过HPLC / MS / MS鉴定为双[4-（二甲基氨基）苯基]甲酮及其N-脱甲基衍生物。基于这些数据，CotA可能导致的CV降解途径包括N提出了由自由基引发的生色团结构的-脱甲基化和裂解。