Sayali R. Naphade*, Annika A. Durve, Meeta Bhot , Jossy Varghese and Naresh Chandra
Pesticides are the substances intended for preventing, destroying, repelling any pest. Due to bulk handling or accidental release, they are accumulated in soil which leads to occasional entry into ecosystems that show lethal effects on living systems. In order to overcome the problem of commonly found pesticides namely Endosulfan, Chlorpyrifos and Cypermethrin. An enrichment culture technique was used to isolate bacterial strains from garden soil tolerating high concentrations of the selected pesticides. Five pure bacterial cultures, named EC1, EC2, EC3, EC4 and EC5 were isolated and subsequently characterized by 16S rRNA gene sequencing and biochemical tests. The optimum temperature, pH and NaCl concentration was determined for them. Growth curve experiments showed that the bacterial isolates were able to grow in medium containing the individual pesticide as the carbon source. Tolerance to high levels of metal salts (Co2+, Ni2+, Cr3+, Cu2+ and Mn2+) and multiple antibiotic resistance was seen in all five bacterial isolates indicating a positive correlation between pesticide degradation and tolerance to metals and antibiotics. By miniprep method of plasmid DNA isolation it was found out that 3 isolates (EC3, EC4 and EC5) showed presence of plasmid DNA indicating that the resistant trait observed was plasmid borne. Further by transformation of the plasmid DNA from EC3, EC4 and EC5 to Escherichia coli DH5α strain, it was found that the transformed strain acquired the ability to grow in presence of higher concentrations of pesticides. Thus such findings may be useful in designing a multi resistant bacterium that can be used to return the altered environment to its original condition
