Isolation, Characterization and Identification of Organophosphate Pesticide Degrading Bacterial Isolates and Optimization of their Potential to Degrade Chlorpyrifos

Current study was aimed to isolate indigenous organophosphate (OP) degrading soil bacteria from agricultural soils of Mochh, district Mianwali, Pakistan.Among a large number of bacterial isolates obtained, four best bacterial isolates (MB490, MB497, MB498 and MB504) were selected based on their tolerance against multiple OP pesticides (Chlorpyrifos, Triazophos and Dimethoate), for further analyses to optimize their potential to degrade Chlorpyrifos (CPF).These isolates could tolerate 0.8-8 g L -1 of Chlorpyrifos, 2-4 g L -1 of Triazophos and 0.22-4 g L -1 of Dimethoate.These bacteria showed multiple heavy metal resistance and possessed enzymes like Nitrate reductase, Oxidase and Catalase needed for biodegradation.When analyzed for CPF degradation by HPLC, these isolates exhibited 67.22 to 99.48% degradation of CPF (200 mg L -1 ) in M-9 broth under wide range of pH (6, 7 and 8) and temperatures (25, 30 and 37•C).Strain MB490 displayed maximum CPF degradation at pH 6, while other three isolates were best at alkaline pH 8. Isolates MB490 and MB498 were best degraders of CPF at 37•C in comparison to MB497 and MB504, which showed highest degradation at 30•C.These four strains were identified as Pseudomonas kilonensis MB490, Bacillus thuringiensis MB497, Pseudomonas kilonensis MB498 and Pseudomonas sp.MB504 based on 16S rRNA analysis.The above findings suggest that these novel isolates can be used efficiently under a wide range of temperature and pH for remediation of Chlorpyrifos polluted agricultural soils and water resources under local conditions.