Streptomyces sp. SCBT Isolated from Rhizosphere Soil of Medicinal Plants is Antagonistic to Pathogenic Bacteria

The Streptomycetes sp. SCBT strain Gen Bank accession number EU143270 isolated from the rhizosphere soil of medicinal plants was collected from the Kolli hills of Tamil Nadu, India. The strain Streptomyces is designated as School of Chemical and Biotechnology (SCBT), capable of inhibiting the growth of a wide range of Gram-negative and Gram-positive bacteria. An almost complete 16S rRNA gene sequence of the isolate was generated and compared with sequences of representative Streptomyces spp. The 16S rRNA data supported the classification of the strain within the genus Streptomyces, and showed that the SCBT strain was closely related to Streptomyces albogriseolus ATCC AJ494865 with a sequence similarity of 99%. Despite the high sequence similarity, SCBT was phenotypically different from S. albogrieseolus ATCC AJ494865. When the strain was cultured, its culture broth was extracted with ethyl acetate and the contents of the residue were subjected to Liquid Chromatography Mass Spectrum (LCMS) profiling. The chromatographic purity of the peak exhibiting the antimicrobial activity at a Retention time (RT) of 16.2 min was 48%, and the compound was purified. The mass/change (m/z) value of the peak exhibiting antimicrobial activity at the RT of 16.2 min was 391 isotopic ion peak (M+1).