Biodegradation of imidacloprid by soil isolate brevundimonas sp. Mj15

Imidacloprid (I - [(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine), is a chloronicotinyl insecticide used to control biting and sucking insects. Enrichment cultures from soil samples were made to isolate imidacloprid degrading bacteria. Soil isolates were tested for their ability to degrade imidacloprid in minimal salt medium (MSM) and tryptic soya broth (TSB). Further plasmid was isolated and curing was performed with acryflavin to establish the role of plasmid in degradation. Two soil-free stable enrichment cultures imi-01 and imi-05 were obtained. Strain SP-01 isolated from the enrichment cultures degraded 38 and 69 % of imidacloprid in MSM and TSB respectively in four weeks as confirmed by HPLC analysis at 0, 7, 14, and 28th day of incubation to determine imidacloprid concentration. Soil isolate SP-01 was identified as Brevundimonas Sp. MJ 15 by morphology, biochemical characters and 16S rDNA sequencing. Further a plasmid was detected in Brevundimonas Sp. MJ 15 and was cured in third generation. The cured cells showed 14.80% degradation compared to 58% degradation shown by non cure cells in TSB. Present investigation revealed that Brevundimonas Sp. MJ 15 was able to degrade imidacloprid in MSM and TSB. Further plasmid curing revealed that the genes responsible for imidacloprid degradation are located both in plasmid and chromosome.