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

Isolation and characterization of 4 benzene/toluene-degrading bacterial strains and detection of related degradation genes

分别以苯、甲苯为碳源，从厦门污水处理厂活性污泥中富集筛选获得了2株苯降解菌B1、B2和2株甲苯降解菌J2、J6。16S rRNA基因鉴定结果表明B1、J2属于假单胞菌属（Pseudomonas sp．），B2、J6属于不动杆菌属（Acinetobacter sp．）。研究表明，这些菌在pH7～10的碱性范围内能很好生长。在以0．1％（V／V）苯或甲苯为唯一碳源的无机盐培养基中，B1、B2菌在72小时内对苯的降解率分别为67．7％、94．2％，J2、J6菌对甲苯的降解率分别为92．4％、84．8％。简并PCR扩增、序列分析表明，这些菌含有相同的苯双加氧酶基因，表明苯降解基因在这些降解菌中可能存在水平转移。此外，J2，J6两株菌还含有甲苯双加氧酶基因，而且J2能在甲苯浓度为70％（V／V）的LB培养基中生长。这些降解菌在苯、甲苯污染的生物治理中有应用前景。

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℃ to 37℃, 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 72hrs 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.