Isolation and characterization of 4 benzene/toluene-degrading bacterial strains and detection of related degradation genes
4株苯系物降解菌菌株的筛选鉴定、降解特性及其降解基因研究

Four bacteria with the ability of benzene or toluene degradation were isolated from the active sludge of a life sewage treatment farm, two of which degraded benzene, and named B1 and B2; and other two degraded toluene, and named J2 and J6, respectively. Sequence analysis of 16S rDNA showed that strain B1 and J2 belonged to Pseudomonas, and B2, J6 belonged to Acinetobacter. They all well adapted to the circumstances from 18 degrees C to 37 degrees C, 0% to 3% NaCl, and pH 7-10. The isolate J2 showed a high tolerance to organic solvent as it could grow well in the medium containing 70% (V/V) toluene, and degraded 92.4% of 0.1% (V/V) toluene within 72 hrs in a medium with toluene as the sole carbon source; while J6 presented 84.8% degradation under the same conditions to toluene. In the case of B1 and B2, they degraded 67.7% and 94.2% of 0.1% (V/V) benzene within 72 hours, respectively. Moreover, all strains were detected harboring the same benzene dioxygenase gene. In addition, J2 and J6 also had toluene dioxygenase genes which share 86.5% homology from each other. These bacteria are of potential in bio-treatment of benzene and toluene pollutants.