Aerobic dichlorvos degradation by smk: complete pathway and implications for toxicity in .

BACKGROUND AND OBJECTIVES

Excess use of pesticides in agricultural field not only compromised soil fertility but also posed serious threat to water bodies and life in the surrounding environment. The leftover pesticide residue needs to be remediated effectively. Compared to physical, chemical and enzymatic remediation options the microbial remediation is more practical and sustainable.

MATERIALS AND METHODS

The smk strain was found to use dichlorvos as the solitary carbon source. Minimal medium supplemented with dichlorvos was used to test ability of bacterium to degrade pesticide aerobically. The metabolites produced by the bacterium were studied with UV-Vis spectrophotometry, HPLC, FTIR and GC-MS techniques. The toxicity studies of neat dichlorvos and smk degraded metabolites were studied by subcutaneous injection in .

RESULTS

The smk strain was found to degrade as high as 80% of dichlorvos on 7 day of incubation, at 30 °C temperature and at pH 7. In five steps complete aerobic degradation of 2,2dicholorvinyl dimethyl phosphate (dichlorvos) resulted in production of free methyl and phosphate. The degradation intermediates produced are 2-Chlorovinyl dimethyl phosphate, vinyl dimethyl phosphate, dimethyl phosphate, methylphosphate and finally free phosphate. The histopathological analysis of liver, spleen and thymus of s were performed to study toxicity of dichlorvos and degraded metabolites.

CONCLUSION

smk could result highest aerobic degradation of dichlorvos to produce free methyl and phosphate. Degradation metabolites could reverse largely toxic effects of dichlorvos when studied in .