Isolation and Characterization of Antibiotic / Antitumor Producing Streptomyces.

A total of 500 Streptomycetes strains were isolated from twenty soil samples and screened for their antimicrobial activity. Only 56 isolates exhibited antimicrobial activity, of which two isolates showed a broad spectrum. They were identified phenotypically and genotypically as Streptomyces fluvissimus-FHM275 and Streptomyces pratensis-FHM572. MIC values of their crude extracts confirmed their antimicrobial potencies. Anticancer activities of the crude extracts were measured against human hepatocellular carcinoma cell line (HePG 2), human Caucasian breast adenocarcinoma (MCF 7), colon cell line (HCT 116) and lung carcinoma cell line (A549) as well as normal human epithelial amnion cells. The crude extract of St fluvissimus- FHM275 showed antitumor activity only against HCT116 and A549 with lC50 15.5, 15.3 µg/ ml and SI, 3.6 and 3.7, respectively; however, St. pratensis-FHM572 showed a wide spectrum of cytotoxic activity towards most tested human antitumor cell lines, its extract appears to be both the most potent and most selective against A549 (IC50 = 7.5 μg/ml, SI = 7.9).