Microcosmic study of endosulfan degradation by Paenibacillus sp. ISTP10 and its toxicological evaluation using mammalian cell line

In the present study, an endosulfan degrading strain Paenibacillus sp. ISTP10 was isolated from activated sludge. Soil microcosms were set up with endosulfan (60 mg kg−1 of dry soil) to evaluate the degradation potency of the strain. Soil samples from the microcosms were collected at regular intervals and the organic compounds were extracted with hexane. GC-MS analysis of the soil extract showed the formation of metabolites of endosulfan such as endosulfan diol and endosulfan ether confirming that the strain degrades endosulfan via a hydrolytic pathway. Methyl tetrazolium (MTT) assay for cytotoxicity and alkaline comet assay for genotoxicity were carried out in human hepato-carcinoma cell line HepG2 to evaluate the toxic potential of endosulfan and its degraded metabolites. The bacterium reduced toxicity as determined by an increase in LC50 value by 75.86 fold and a reduction in Olive Tail Moment by 21 fold after 30 days of treatment. The by-products of degradation were found to be less toxic than the parent compound showing the biodegradation and detoxification potential of endosulfan by Paenibacillus sp. ISTP10.