Biodegradation of fipronil and its metabolite fipronil sulfone by Streptomyces rochei strain AJAG7 and its use in bioremediation of contaminated soil

Fipronil is a most widely used insecticide. It has been found to be highly toxic to insects with alarming decline in honey bees' population. It has shown to cause severe contamination of soil and water. The present study was undertaken to understand the degradation of fipronil and its metabolite fipronil sulfone using actinomycetes. Fipronil degrading actinomycetes strain AJAG7 was isolated from fipronil contaminated agricultural field by enrichment method. Molecular identification by 16S rRNA gene sequencing identified strain AJAG7 as Streptomyces rochei. The biodegradation of fipronil and its metabolite fipronil sulfone by strain AJAG7 was examined by HPLC. Biodegradation pathway of fipronil by strain AJAG7 was deduced with GC MS analysis. Scanning electron microscopy was used to investigate the surface morphological changes of strain AJAG7 upon fipronil degradation. Apart from fipronil degradation, low cost powder formulation of strain AJAG7 was prepared using agricultural waste to remediate the fipronil contaminated agricultural field. Results of the present study suggest that strain AJAG7 qualifies as an ideal candidate for biodegradation of fipronil contaminated environment.