Biological Decolorization and Degradation of Malachite Green by Pseudomonas sp YB2: Process Optimization and Biodegradation Pathway

A novel strain Pseudomonas sp. YB2, which was isolated from activated sludge, was studied for biological decolorization and degradation of malachite green (MG). The results show that this aerobic strain is an aerobic bacterium, which has relatively high salt tolerance and high antibiotic resistance. The optimal performance condition for both bacterial growth and decolorization of MG was at 25-35 A degrees C and pH 5.0-7.0. It could efficiently decolorize 90.40% MG at a high concentration up to 1500 mg/L in 24 h, and concentrations of MG lower than 1000 mg/L could be completely decolorized in 12 h. The intermediate products of MG were detected using gas chromatography-mass spectrometer, including leucomalachite green, 4,4'-bis(dimethylamino) benzophenone, 4-(dimethylamino) benzophenone, phenol, dimethylaniline. The possible degradation pathways of MG by strain YB2 were proposed. This strain might be potentially useful for biodegradation of MG in real environments.