Antimicrobial and cytotoxic properties of Streptomyces sp. (ERINLG-51) isolated from Southern Western Ghats Chandransekar Balachandran 1, *, Veeramuthu Duraipandiyan 1 , Nobuhiko Emi 2 , Savarimuthu Ignacimuthu 1 1 Division of Microbiology and Cancer Biology, Entomology Research Institute, Loyola College, Chennai - 600 034, India 2 Department of Hematology, Fujita Health University, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan * Corresponding author: Dr. C. Balachandran Email:balaeri09@gmail.com Tel: +9144 2817 8348; Fax: +9144 2817 5566 Article History: Received 4 March 2015 Revised 3 May 2015 Accepted 24 May 2015 Published 25 June 2015 Keywords: Streptomyces sp. 6Sr RNA Antimicrobial Cytotoxicity Manuscript details Abstract Te present study aimed for the isolation and characterization antimicrobial metabolite pro- ducing 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 Strep- tomyces sp. (ERINLG-51). Routine microbial identifcation steps, morphology, biochemical characteristics and 16S rRNA analysis confrmed the strain as Streptomyces sp., ERINLG-51. Te antibacterial substance present in the fermentation broth was extracted using ethyl ace- tate. Te results revealed that the ethyl acetate extract showed comparatively better activity against Shigella fexneri, Klebsilella pneumoniae, Pseudomonas aeruginosa, Proteus vulgaris, Bacillus subtilis, Micrococcus luteus, Enterobacter aerogenes, Staphylococcus aureus, Candi- da albicans and Malassezia pachydermatis. Te lowest minimum inhibitory concentrations were: 125 µg/mL against S. fexneri, B. subtilis, M. luteus and P. vulgaris respectively. Inter- estingly, 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 iden- tify novel molecules with potential activity towards pathogenic microorganisms and cancer. South Indian Journal of Biological Sciences 2015; 1(1); 7-14 1. Introduction Soils have been the predominant reservoir for the isola- tion of actinomycetes, particularly the genus Streptomy- ces (Oskay 2004) and soil microbes have been regarded as important sources of biologically active compounds (Donadio et al., 2002). Te occurrence of bacterial resis- tance to a number of antimicrobial agents is becoming a major health problem worldwide. Secondly, the increas- ing use and misuse of existing antibiotics in human and veterinary medicine and in agriculture has further ag- gravated the problem. Several attempts have also been made to prepare novel antibiotics against antibiotic re- sistant microbial infection. Existing literature reveals that almost all groups of microorganisms including bacteria, actinomycetes and fungi produce antimicrobi- al substances as they move into the diverse ecological units. A large number of antimicrobial compounds have been isolated and characterized from flamentous bacte- ria, actinomycetes and many lead compounds from this group of bacteria have acquired a status as potential an- timicrobial agents in medical practice because of their antagonistic efect against clinically important patho- gens (Donadio et al., 2002). Streptomycetes, the Gram positive flamentous bacteria, are widely distributed in a variety of natural and man-made environments, constituting a signifcant component of the microbial population in most soils (Watve et al., 2001; Raja and Prabakaran 2011). Among actinomycetes, around 7,600 compounds are produced by Streptomyces species (Raja and Prabakaran 2011). Streptomycetes are known to be producers of many secondary metabolites with antibacterial, antiparasitic, antifungal, immunosuppressive and antitumor proper- 7 Online ISSN: 2454-4787