Screening of endophytic Streptomycetes isolated from Parthenium hysterophorus L. against nosocomial pathogens.

Parthenium hysterophorus L. is an obnoxious weed of the family asteraceae recognized for its detrimental effects and significant economic losses to agriculture. In this study 42 endophytic streptomycetes strains were isolated from its roots and leaves. The isolates were identified by morphological, microscopic, biochemical and physiological characterization as members of genus Streptomyces. In 16S rRNA gene sequencing the selected isolates exhibited maximum similarity with Streptomyces rochei (99%), Streptomyces litmocidini (99%), Streptomyces enissocaesili (99%), Streptomyces djakartensis (99%), Streptomyces olivaceus (99%), Streptomyces spp (99%), Streptomyces plicatus (99%), Streptomyces geysiriensis (99%) and Streptomyces vinaceusdrappus (99%). In biological screening the crude extracts of 12 strains exhibited significant antimicrobial activity against multi drug resistant nosocomial pathogens including Pseudomonas, Enterobacter, Bacillus, Escherichia coli, Staphlococcus aureus and Candida albicans. In chemical screening by thin layer chromatography (TLC) the extracts exhibited an impressive diversity of the bioactive secondary metabolites. Additionally high performance liquid chromatography (HPLC-UV) chromatographs revealed many impressive peaks of unidentified bioactive metabolites. As such this is a first study reporting the isolation, identification and screening of endophytic Streptomyces from the invasive weed. The results provide an insight into an untapped endophytic environment yet to be explored which might be a promising source of lead antimicrobial agents.