Isolation and identification of the pesticides chlorpyrifos degrading bacteria from contaminated soils
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
Chlorpyrifos is an organic phosphorus pesticide which has a wide range of effectiveness, therefore it has gained a lot of attention from many agricultural producers in recent years. The primary environmental concerns associated with its use namely, killing birds, surface water pollution, and destructive effects on aquatic species were taken into consideration. Biodegradation of pesticides is one of the methods for cleaning up soil, which is cost effective and adaptive with environment. Using degrading microbes, including bacteria to decompose organic compounds is in fact one of the primary ways to remove these contaminants from various environments. High performance liquid chromatography is found to be widely used in the analysis of pesticides, especially in the measurement of the remnant. For the purpose of screening chlorpyrifos' indigenous degrading bacteria, samples from different industrial and agricultural siols were collected and isolated in mineral base environment. After samples' enrichment in the mineral medium, by cultivation on solid medium, 15 different morphologically isolates were isolated and purified, and using biochemical and morphological methods they were identified to species level. The concentration of the pesticide chlorpyrifos in the presence of these strains in the medium was determined using high performance liquid chromatography (HPLC). The results showed that, among other isolates which had pesticide chlorpyrifos degrading bacteria, S1 and S2 isolates' concentration was reduced within 15 days after the planting from 50 mg.l, to respectively, 2.15 and 3.21 mg.l , these isolates had the utmost ability to reduce the concentration in comparison with other isolates. Considering the growth of bacteria in poor media it can be concluded that these strains use the pesticide chlorpyrifos as an energy source for their growth. According to the results of 16S rDNA amplification and sequencing of isolates, S1 and S2 had the highest similarity to the genus of Paenibacillus and Enterobacter. The results of this study showed that the pesticides chlorpyrifos degrading bacteria existed in contaminated areas and also in the sewage system of industrial areas. Therefore, these isolates can be used for biological cleaning, after checking them on the field level and determining their formulation.
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