Pesticide Induced Variations in Six Natural Isolates of Escherichia coli from Drrnking Water Using A Cullure Dependent Approach

The paper deals with the effect of four pesticides on E. coli strains selonging to six serogroups (O20, O25, O40, O58, O73, O80), isolated from drinking water of Agra city, using the growth zone of inhibition test and the agar plate count methods. The results reveal that pesticides, except for endosulfan, cause a relatively mild toxicity to E. coli, since they get acclimated to these toxicants, as the duration of exposure increases. Malathion and lindane were observed to favor bacterial growth even at pesticide concentrations as high as 10 mg L⁻¹. A positive correlation was observed between the pesticide concentrations and colony forming units for malahtion and lindane, while endosulfan and chloropyriphos showed a negative correlation, though endosulfan showed a recovery in growth patterns after 10 h of treatment at pesticide concentrations ranging from 0.1–10 mg L⁻¹.