CHLORPYRIFOS RESISTANT BACTERIA FROM PAKISTANI SOILS: ISOLATION, IDENTIFICATION, RESISTANCE PROFILE AND GROWTH KINETICS

Haphazard use of pesticides has been a potential source of ecological imbalance in addition to their genetic activity. The soil microflora (under persistence pesticide stress) are able to detoxify/degrade these toxic compounds into non toxic products. Chlorpyrifos (a trichloropyridinyl phosphothioate) is one of the most widely used pesticides that exert broad based toxic effects. The present study was initiated to isolate, identify and characterize the chlorpyrifos resistant bacteria from cotton cultivated soil of NIAB, Faisalabad, Pakistan (using conventional and API kit methods). Out of 20 isolates 3 chlorpyrifos hyper resistant bacteria were finally selected for follow up studies. The screening was performed by replica device. Three isolates viz., Ps. putida, Aeromonas sp., and Klebsiella sp., were found resistant to 2mg/mL, 4mg/mL and 8mg/mL of chlorpyrifos while Ps. putida and Aeromonas sp., also resisted the 10mg/mL and 20mg/mL doses. Growth kinetic studies revealed that under highly stressed conditions of chlorpyrifos, the generation time was extended compared to shorter generation time in plain liquid medium. Further studies (including analysis of the chlorpyrifos degraded products) are in progress.

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