Biodegradation of Chlorpyrifos by Pseudomonas indica Isolated from Pesticide Contaminated Soil

Chlorpyrifos (O, O-diethyl O-3, 5, 6-trichloro-2-pyridyl phosphorothioate) is a widely used broad-spectrum chlorinated organophosphate pesticide whose widespread and indiscriminate use has led to several environmental problems. Soil microflora hold potential for its detoxification. It has been shown to be degraded co-metabolically in liquid media by bacteria. This study reports bacteria capable of degrading chlorpyrifos from pesticide contaminated agricultural soil by enrichment culture technique using mineral salts media supplemented with chlorpyrifos as the carbon source. A total of 20 morphologically different colonies were obtained and the percentage degradation estimated by HPLC analysis and the degradation confirmed by GC-MS analysis. Out of 20, seven bacterial isolates namely PKDB1, PKDB2, PKDB3, AKB1, AKB2, AKB3 and KMB1 showed significant reduction in the peak area values compared to that of the control. The isolate PKDB2 which showed highest degradation (90.98%) has been identified as Pseudomonas indica based on morphological, biochemical and molecular characterization.