Biodegradation of malachite green by Micrococcus sp. strain BD15: Biodegradation pathway and enzyme analysis

Malachite green (MG) is extensively used, although it is carcinogenic and mutagenic. In our previous study, the novel Micrococcus sp. strain BD15 was observed to efficiently decolorize MG. The aims of this study were to identify the metabolites after degradation by this strain and to identify the enzymes involved in degradation. UV–Visible, FTIR, GC–MS and LC–MS analyses were performed to determine the degradation products, and our results indicate that the intermediates of MG degradation include 4-(Dimethylamino)benzophenone, Michler's ketone, 4-(methylamino)benzophenone, 4-aminobenzophenone, 4-methylaminobenzoic acid, 4-hydroxyl-N,N-dimethylaniline, N,N-dimethylaniline, hydroxyl-4-(dimethylamino)benzophenone and 4-hydroxyl-aniline. In addition, enzyme analysis revealed that laccase and NADH-DCIP reductase are involved in the degradation of MG. To our knowledge, this is the first study of the detailed biodegradation pathway of MG by Micrococcus sp. strains. ► The degradation products of MG by strain BD15 were identified. ► The possible degradation pathway of MG by strain BD15 was proposed. ► The laccase and NADH-DCIP reductase were involved in the biodegradation of MG.