Biotransformation Studies on Organochlorine Insecticide, Endosulfan by Indigenous Bacterial Isolate

Aerial application of persistent, bioaccumulative organochlorine pesticide endosulfan on cashew plantations to protect it from mosquito bug has led to contamination of soil and water environments in several parts of South Canara region, India. Endosulfan and its toxic residues like endosulfan sulfate are posing several threats to non-target organisms including humans. Biotransformation of toxic compounds using indigenous microbial strains is considered as safe and cost effective technique in bioremediation. In the present work, the bacterial strain designated as ES-1, has been isolated from the soil by enrichment method. The bacterial strain was found to mineralize endosulfan ˃99% of 100 mg/l completely biotically after 14 days of incubation by forming unknown polar metabolites.Whereas, abiotic degradation resulted in formation of a toxic compound, endosulfan sulfate. Based on 16s rDNA sequence analysis, the strain ES-1 showed 99% similarity to Bacillus sp. The results from the work suggest that, this bacterial strain could be employed for remediation of endosulfan contaminated environments.