Molecular Genotyping and Antimicrobial Activities of Secondary Metabolites from Streptomyces sp: Taxonomy, Extraction and Purification

Abstract

A total of 57 native actinomycetes cultures with distinct characteristics were isolated from a field soil sample collected from Gulbarga region, Karnataka state, India. Out of these isolates, 4 potent isolates showed antibacterial activity against clinical pathogens in primary screening process by cross streak technique. The secondary metabolites produced by one of the strain Streptomyces sp. GUT 21 was selected further having broad range of antibacterial activity and was subjected for bulk production. The active metabolite was extracted using ethyl acetate (1:1, v/v) at pH 7.0 by phase-solvent extraction method. This extracted compound is active in vitro against multi-drug resistant (MDR) organisms like Escherichia coli (MTCC 9537), Klebsiella pneumoniae (MTCC 109), Pseudomonas aeruginosa (MTCC1688) and Staphylococcus aureus (MTCC 96). The purified compound was additionally characterised by series of chromatography techniques and spectroscopic methods like FTIR and mass spectra. Based on the results of FT-IR and mass spectrometry, the active molecule (fraction 10) was provisionally predicted as 2,4-bis (1,1-dimethylethyl) phenol with molecular formula of C₁₄H₂₂O.According to the morphological, cultural, physiological and biochemical characteristics, and 16S rDNA sequence analysis, the potential strain GUT 21 was identified as Streptomyces sp. (GenBank Accession number KU500633).

Key words:

• Streptomyces
• multi-drug resistant
• secondary metabolites
• rep-PCR
• PKS/NRPS gene
• ARDRA