Screening of chlorobenzene-degrading bacterium and purification of its degradation enzyme

Abstract:

Abstract:［Objective］We screened a bacterial strain capable of degrading chlorobenzene，and purified the corresponding degradation enzyme．［Methods］ The strain was screened by gradient enrichment culture and sterile filter paper plate method，and identified by morphology and 16S rRNA gene sequence． Chlorobenzene concentration in the liquid culture was determined by gas chromatography． Degradation capability was assayed by the proportion of chlorobenzene degraded per cell． The purity quotient and molecular weight of the purified degradation enzyme were determined by gel electrophoresis.［Results］The isolated bacterium，LW13，used chlorobenzene in activated sludge as sole carbon and energy source．Cells were 2.3 μm long and 0.8 μm wide，with several terminal flagella． Strain LW13 was 95.5% similar to Lysinibacillus fusiformis，and its degradation enzyme was a positively-charged exoenzyme (molecular weight about 57 kDa)．The optimal temperature and pH of the purified enzyme were approximately 40 °C and 8.0，respectively．［Conclusion］Strain LW13 belongs to genus Lysinibacillus，and can degrade chlorobenzene (500－2000 mg/L)．