Effects of soil pH on the biodegradation of chlorpyrifos and isolation of a chlorpyrifos-degrading bacterium
Effects of soil pH on the biodegradation of chlorpyrifos and isolation of a chlorpyrifos-degrading bacterium
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DOI：
10.1128/aem.69.9.5198-5206.2003
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发表时间：
2003-09-01
影响因子：
4.4
通讯作者：
Wright, DJ
中科院分区：
文献类型：
--
作者：
Singh, BK;Walker, A;Wright, DJ
我们研究了微生物在英国和澳大利亚土壤中降解有机磷杀虫剂毒死蜱的作用。5种英国土壤在pH为4.7~8.4范围内的降解动力学表明，毒死蜱的消散是由土壤微生物的共代谢活动介导的。在这些土壤中反复使用毒死蜱并没有导致微生物种群的发展，使其具有更强的降解农药的能力。在澳大利亚的土壤中发现了一个利用毒死蜱作为碳源的强大细菌种群。澳大利亚土壤中毒死蜱降解能力的增强被成功地转移到联合王国的五种土壤中。只有pH大于或等于6.7的土壤才能在接种90天后保持这种降解能力。利用聚合酶链式反应-变性梯度凝胶电泳法(DGGE)对细菌16S rRNA基因进行分子指纹分析，以监测降解微生物从澳大利亚土壤向英国土壤的转移和增殖。发现两条带与毒死蜱的加速降解有关。带1与肠杆菌及其近缘菌的序列相似，带2与假单胞菌的序列相似。以澳大利亚土壤为接种物来源的液体浓缩培养，分离到一株毒死蜱降解菌。该菌株有一个16S rRNA基因，其序列与澳大利亚土壤DGGE图谱中带1的序列相同。DNA探测表明，在英国土壤中存在与已知的有机磷降解(OPD)基因相似的基因。然而，在澳大利亚土壤和分离的降解菌中没有检测到DNA杂交信号。这表明在澳大利亚土壤和毒死蜱降解分离物中都存在无关基因。这些结果与我们的观察结果一致，即毒死蜱在这些系统中的降解是不寻常的，因为它与生长相关，涉及完全矿化。由于该分离物的16S rRNA基因与澳大利亚土壤中可见的DGGE条带匹配，该分离物很可能是突出的，并参与了毒死蜱在该土壤中的降解。
We examined the role of microorganisms in the degradation of the organophosphate insecticide chlorpyrifos in soils from the United Kingdom and Australia. The kinetics of degradation in five United Kingdom soils varying in pH from 4.7 to 8.4 suggested that dissipation of chlorpyrifos was mediated by the cometabolic activities of the soil microorganisms. Repeated application of chlorpyrifos to these soils did not result in the development of a microbial population with an enhanced ability to degrade the pesticide. A robust bacterial population that utilized chlorpyrifos as a source of carbon was detected in an Australian soil. The enhanced ability to degrade chlorpyrifos in the Australian soil was successfully transferred to the five United Kingdom soils. Only soils with a pH of greater than or equal to6.7 were able to maintain this degrading ability 90 days after inoculation. Transfer and proliferation of degrading microorganisms from the Australian soil to the United Kingdom soils was monitored by molecular fingerprinting of bacterial 16S rRNA genes by PCR-denaturing gradient gel electrophoresis (DGGE). Two bands were found to be associated with enhanced degradation of chlorpyrifos. Band 1 had sequence similarity to enterics and their relatives, while band 2 had sequence similarity to strains of Pseudomonas. Liquid enrichment culture using the Australian soil as the source of the inoculum led to the isolation of a chlorpyrifos-degrading bacterium. This strain had a 16S rRNA gene with a sequence identical to that of band 1 in the DGGE profile of the Australian soil. DNA probing indicated that genes similar to known organophosphate-degrading (opd) genes were present in the United Kingdom soils. However, no DNA hybridization signal was detected for the Australian soil or the isolated degrader. This indicates that unrelated genes were present in both the Australian soil and the chlorpyrifos-degrading isolate. These results are consistent with our observations that degradation of chlorpyrifos in these systems was unusual, as it was growth linked and involved complete mineralization. As the 16S rRNA gene of the isolate matched a visible DGGE band from the Australian soil, the isolate is likely to be both prominent and involved in the degradation of chlorpyrifos in this soil.