Supreeth M, Chandrashekar M A, Sachin N, Raju N S
Department of Studies in Environmental Science, University of Mysore, Manasagangothri, Mysuru, 570006, Karnataka, India.
3 Biotech. 2016 Dec;6(2):147. doi: 10.1007/s13205-016-0462-2. Epub 2016 Jun 24.
The application of pesticides in agricultural fields not only reaches the target pests but also with soil where it interacts with soil microorganisms resulting in change of microbial diversity. Chlorpyrifos (CP) is one such organophosphorous insecticide most widely used against various insects, termites, and beetles throughout the globe. In the present work, the effect of CP on soil microbial population was assessed by the cultivable method. The fertile soil which does not have a history of any pesticide application was treated with 100 and 200 µg/g of CP along with control which received only sterile water and incubated for 1, 7, and 14 days. The soil amended with the insecticide showed decrease in the number of colony forming units (CFU) of bacteria and fungi. However, Streptomyces sp. HP-11 which tolerated high concentration and also inhibited fungal population was further selected for biodegradation studies. After 14 days of incubation in Mineral salt media (MSM), the strain HP-11 biotransformed CP into 3, 5, 6-trichloro-2-pyridinol (TCP) and Diethyl Phosphorothioate (DETP), and its formation was confirmed by the m/z peak of LC-MS analysis, which was later metabolized to unknown polar metabolites. The results obtained highlights that the application of chlorpyrifos favored the Actinomycete growth in the soil, thereby inhibiting other microorganisms and the strain HP-11 harbors metabolic pathway for detoxification of CP and its hydrolysis product TCP into polar metabolites, thus suggesting the strain HP-11 will be a potential bioaugmenting agent for the bioremediation of chlorpyrifos contaminated soil and water.
在农田中施用农药不仅会作用于目标害虫，还会进入土壤，与土壤微生物相互作用，导致微生物多样性发生变化。毒死蜱（CP）就是这样一种有机磷杀虫剂，在全球范围内被广泛用于防治各种昆虫、白蚁和甲虫。在本研究中，采用可培养方法评估了毒死蜱对土壤微生物种群的影响。将未使用过任何农药的肥沃土壤分别用100和200微克/克的毒死蜱处理，同时设置仅接受无菌水的对照，然后培养1、7和14天。用该杀虫剂处理过的土壤中细菌和真菌的菌落形成单位（CFU）数量减少。然而，进一步选择了耐受高浓度并能抑制真菌种群的链霉菌属HP - 11进行生物降解研究。在矿物盐培养基（MSM）中培养14天后，菌株HP - 11将毒死蜱生物转化为3, 5, 6 - 三氯 - 2 - 吡啶醇（TCP）和二乙基硫代磷酸酯（DETP），其形成通过液相色谱 - 质谱分析的m/z峰得到证实，随后这些产物被代谢为未知的极性代谢物。所得结果表明，毒死蜱的施用有利于土壤中放线菌的生长，从而抑制其他微生物，并且菌株HP - 11具有将毒死蜱及其水解产物TCP解毒为极性代谢物的代谢途径，因此表明菌株HP - 11将是用于生物修复毒死蜱污染土壤和水的潜在生物强化剂。
