Antimicrobial and Cytotoxic Properties of Streptomyces Sp. (ERINLG-51) Isolated from Southern Western Ghats

The present study aimed for the isolation and characterization antimicrobial metabolite producing Streptomyces sp. from the Dolphin Nose hills, Nilgiris, Southern Western Ghats, India. Primary screening of the strains towards antimicrobial activity guided to select a novel Streptomyces sp. (ERINLG-51). Routine microbial identification steps, morphology, biochemical characteristics and 16S rRNA analysis confirmed the strain as Streptomyces sp., ERINLG-51. The antibacterial substance present in the fermentation broth was extracted using ethyl acetate. The results revealed that the ethyl acetate extract showed comparatively better activity against Shigella flexneri, Klebsilella pneumoniae, Pseudomonas aeruginosa, Proteus vulgaris, Bacillus subtilis, Micrococcus luteus, Enterobacter aerogenes, Staphylococcus aureus, Candida albicans and Malassezia pachydermatis. The lowest minimum inhibitory concentrations were: 125 μg/mL against S. flexneri, B. subtilis, M. luteus and P. vulgaris respectively. Interestingly, the ethyl acetate extract showed cytotoxic activity against A549 lung adenocarcinoma cancer cell line. It showed 72% activity at the dose of 1000 μg/mL with IC50 value of 600 μg/ mL. In conclusion the crude extract of Streptomyces sp., ERINLG-51 could be useful to identify novel molecules with potential activity towards pathogenic microorganisms and cancer.