Isolation and characterization of butachlor-catabolizing bacterial strain Stenotrophomonas acidaminiphila JS-1 from soil and assessment of its biodegradation potential

Aims: Isolation, characterization and assessment of butachlor-degrading potential of bacterial strain JS-1 in soil. Methods and Results: Butachlor-degrading bacteria were isolated using enrichment culture technique. The morphological, biochemical and genetic characteristics based on 16S rDNA sequence homology and phylogenetic analysis confirmed the isolate as Stenotrophomonas acidaminiphila strain JS-1. The strain JS-1 exhibited substantial growth in M9 mineral salt medium supplemented with 3 center dot 2 mmol l-1 butachlor, as a sole source of carbon and energy. The HPLC analysis revealed almost complete disappearance of butachlor within 20 days in soil at a rate constant of 0 center dot 17 day-1 and half-life (t(1/2)) of 4 center dot 0 days, following the first-order rate kinetics. The strain JS-1 in stationary phase of culture also produced 21 center dot 0 mu g ml-1 of growth hormone indole acetic acid (IAA) in the presence of 500 mu g ml-1 of tryptophan. The IAA production was stimulated at lower concentrations of butachlor, whereas higher concentrations above 0 center dot 8 mmol l-1 were found inhibitory. Conclusions: The isolate JS-1 characterized as Stenotrophomonas acidaminiphila was capable of utilizing butachlor as sole source of carbon and energy. Besides being an efficient butachlor degrader, it substantially produces IAA. Significance and Impact of the Study: The bacterial strain JS-1 has a potential for butachlor remediation with a distinctive auxiliary attribute of plant growth stimulation.