Isolation and Characterization of Chlorpyrifos Degrading Bacteria from Contaminated Agricultural Lands

Previous literature has confirmed that pesticides are posing serious threats to the lives of human beings and animals alike because of their use in agricultural crops. Pesticides have also increased pollution in aquatic and terrestrial environment. In this study, chlorpyriphos degrading bacterial strains were isolated from pesticide contaminated agricultural soils by the selective enrichment method. Bacterial isolates were biochemically characterized for the strain identification. The effect of different environmental factors on optimum growth was also checked. These factors included pH, temperature, and concentration of pesticide. Isolated strains were also ribotyped for identification. Metal resistance profiling was performed for different heavy metals, that is, ZnSO4.7H2O (Zinc sulphate), CdCl2.H2O (Cadmium chloride), CuSO4 (Copper sulphate), and K2CrO4 (Potassium chromate). It was found that strains NW3O and NW3T were sensitive to cadmium except NR2 and NR4, which were resistant at the concentration of 100 and 200 µg ml-1. NR4, NW4 and NW3G were resistant to chromium upto the concentration of 100 µg ml-1, while NR2, NW3O and NW3T tolerated 200 µgml-1 of the metal. All the strains were resistant to zinc at different concentrations. NR2 showed maximum resistance to copper by showing growth on all concentrations of the metal. Thin layer chromatography was performed for the detection of different intermediates formed during the degradation of chlorpyrifos. Minimum inhibitory concentration of pesticide was estimated in M9 medium containing chlorpyriphos. The current study resulted in the isolation of efficient chlorpyrifos degrading strains with a wide range of pH and temperature tolerance that can utilize chlorpyrifos upto 700mg/L during lab scale degradation tests (growth on chlorpyrifos supplemented minimal agar and broth).