不同降解茵对甲基毒死蜱及3,5,6-三氯-2-吡啶酚的降解能力比较

为掌握微生物降解甲基毒死蜱的特性与机制,首先从土壤中分离不同的甲基毒死蜱降解茵,然后对其降解效率、降解过程中中间产物3,5,6-三氯-2-吡啶酚(TCP)的质量浓度变化、对TCP与其他6种有机磷农药的降解能力以及磷酸酯酶活性进行了测试分析.结果表明,分离到2株能高效降解甲基毒死蜱的菌株,经鉴定命名为地衣芽孢杆菌ZL-7与荧光假单胞茵ZHLXL-2,其降解甲基毒死蜱的5d降解率分别为90.6％和99.4％;在菌株ZL-7降解甲基毒死蜱的过程中检出了TCP,而在菌株ZHLXL-2的降解过程中未检出.菌株ZHLXL-2能降解TCP,48 h降解率可达91.0％,而菌株ZL-7不能降解TCP.两菌株都能降解6种供试的有机磷农药,但菌株ZL-7降解率更高,其10 d降解率在92.1％ ～99.8％,菌株ZHLXL-2的10 d降解率为89.2％～93.4％;同时菌株ZL-7的磷酸酯酶活性显著高于菌株ZHLXL-2.分析表明,这2种菌株的磷酸酯酶活性与其降解有机磷农药的能力呈正相关性,而菌株ZHLXL-2因可有效降解中间物TCP,从而能更快地降解甲基毒死蜱.

Biodegradation of Chlorpyrifos-methyl and Its Hydrolysis Product 3,5,6-Trichloro-2-pyridinol by Different Degrading Bacteria

To understand the degradation characteristics and mechanism of chlorpyrifos-methyl by microorganisms,First,different chlorpyrifos-methyl degrading bacteria were isolated from soil,and then,their degradation characteristics were tested and analyzed,including degradation efficiency on chlorpyrifosmethyl,variation of intermediate (3,5,6-trichloro-2-pyridinol,TCP) concentration in the degradation process,phosphatase activity,degradation ability on TCP and 6 organophosphorus pesticides.Two chlorpyrifos-methyl degrading bacteria were isolated,which were identified as Bacillus licheniformis ZL-7 and Pseudomonasfluorescens ZHLXL-2,and their degradation rates on chlorpyrifos-methyl were 90.6％ and 99.4％ respectively in five days.TCP was found in the degradation process of chlorpyrifos-methyl by the strain ZL-7,but not by the strain ZHLXL-2.The strain ZHLXL-2 could degrade TCP,and the degradation rate reached 91.0％ at 48 h,while the strain ZL-7 could not degrade TCP.Both strains could degrade 6 kinds of organophosphorus pesticides.The 10 d degradation rate of 6 organophosphorus pesticides by the strain ZL-7 was 92.1％-99.8％,higher than the degradation rate by the strain ZHLXL-2 (89.2％-93.4％).In addition,the phosphatase activity of strain ZL-7 was significantly higher than that of strain ZHLXL-2.These results showed that the phosphatase activity of the two strains was positively correlated with their ability to degrade organophosphorus pesticides.The strain ZHLXL-2 could degrade chlorpyrifosmethyl more quickly because of its ability to degrade TCP effectively.