一株毒死蜱降解菌的固定化条件优化研究

Optimization in the Immobilization Conditions of the Bacillus cereus Bacteria

采用在50 m L三角瓶中定量添加毒死蜱药液和固定化菌的方法研究了不同包埋条件对固定化蜡状芽孢杆菌(Bacillus cereus)降解毒死蜱的影响,最后将固定化条件进行了正交试验的优化。结果表明,游离化菌体的菌龄为20 h对初始浓度为50mg/L毒死蜱的降解率达最高。从降解曲线得出,海藻酸钠固定化菌降解毒死蜱的反应时间为24h时降解率达75.4%;菌体和海藻酸钠溶胶的包埋比为1∶20对毒死蜱的降解率达最高为76.8%;随着成型剂Ca Cl2浓度的增大,固定化菌对毒死蜱的降解率先上升后下降,Ca Cl2浓度为2%对毒死蜱的降解率达最大为82.6%,海藻酸钠溶胶浓度为3%对初始浓度为50 mg/L毒死蜱的降解率达最大为85.7%。通过正交试验得出,海藻酸钠浓度(A)、Ca Cl2浓度(B)和固定化时间(C)三者对固定化菌降解毒死蜱的影响都达到显著水平(P<0.05),影响次序依次为C>A>B,最优水平分别为海藻酸钠浓度3.0%、Ca Cl2浓度1.5%和固定化时间32 h。因此,固定化蜡状芽孢杆菌对毒死蜱的降解率较高,在毒死蜱水体污染的降解去毒方面具有的应用价值较大。

The effect of different embedding condition on the degradation rate of chlorpyrifos by the immobilized Bacillus cereus bacteria were studied by quantitatively adding chlorpyrifos and immobilized bacteria in the 50 m L erlenmeyer flask. The results showed that the degradation rate of chlorpyrifos was the highest as the bacteria age was 20 h. In the degradation curve,the degradation rate reached 75. 4% when the reaction time was 24 h. The degradation rate reached 76. 8% when the embedding ratio of cell and sodium alginate sol was 1∶ 20. With the increase of the Ca Cl2 concentration,the degradation rate of chlorpyrifos by the immobilized bacteria first increased and then decreased,and the degradation rate reached the maximum of 82. 6% as the concentration of forming agent Ca Cl2 was 2% for 28 h. Simultaneously,the conclusion was drawn that the degradation rate reached a maximum of 85. 7% as the sodium alginate sol concentration was 3%. Finally,through orthogonal test,the effect of sodium alginate concentration,calcium chloride concentration and immobilization time on the degradation rate of chlorpyrifos were all at the significant level（ p〈0. 05）,the effect order sequentially as immobilization time〉 sodium alginate concentration〉 calcium chloride concentration,optimal levels were the sodium alginate concentration of 3%,calcium chloride concentration of 1. 5% and the immobilization time of 32 h.Therefore,the degradation rate of chlorpyrifos by immobilized Bacillus cereus bacteria was higher,which had potential application value in the water detoxification of chlorpyrifos pollution.