Biodegradation of imidacloprid by consortium of two soil isolated Bacillus sp.

Imidacloprid degradation potential of bacterial cultures from sugarcane growing soils was studied in liquid culture and Bacillus aerophilus and Bacillus alkalinitrilicus showed maximum potential to degrade imidacloprid. Hence, into a clay loam soil imidacloprid was added at 50, 100, and 150 mg kg(-1) along with 45 × 10(7) cells g(-1) soil of both species under autoclaved and unautoclaved conditions. Under autoclaved conditions imidacloprid residues were degraded after 56 days to 3.18, 5.83 and 10.48 mg kg(-1) and under unautoclaved conditions to 5.17, 6.23 and 10.31 mg kg(-1). 6-chloronicotinic acid, nitrosimine and imidacloprid-NTG metabolites were detected in measurable concentrations under both conditions. Dissipation pattern of imidacloprid did not follow first order kinetics under both sets of conditions. The half life value of imidacloprid ranged from 13 to 16 days after bacterial inoculation. This is first report of use of mixed culture of native soil bacterial isolates for remediation of imidacloprid contaminated soils.