Decolorization and biodegradation of triphenylmethane dyes by a novel Rhodococcus qingshengii JB301 isolated from sawdust

A sawdust sample collected from a wet environment was used to screen for crystal violet-decolorizing and methyl violet-decolorizing bacterial strains. A strain with degrading and decolorizing abilities was isolated and identified as Rhodococcus qingshengii JB301. The decolorization of crystal violet and methyl violet was improved by optimizing culture conditions. Based on liquid chromatography–mass spectrometry (LC-MS) analysis, similar degradation products of crystal violet and methyl violet were detected, while [N,N-dimethylaminophenyl] [aminophenyl] benzophenone or [N-methylaminophenyl] [N-methylaminophenyl] benzophenone was different from previous reports. A common degradation pathway was established to demonstrate the mechanism of crystal violet and methyl violet decolorization. It was found that lignin peroxidase activity was greatly enhanced after addition of crystal violet (by 514 %) and methyl violet (by 698 %) at 12 h, while NADH-DCIP (dichlorophenolindophenol) reductase activity was inhibited by the dyes. The growth of Triticum aestivum was inhibited by both dyes and the toxicity of the dyes was weakened after the degradation by R. qingshengii JB301.