COMBATING THE EMERGING DRUG-RESISTANT PSEUDOMONAS AERUGINOSA BY AN ANTIBIOTIC PURIFIED FROM THE NOVEL STREPTOMYCES VIOLASCENS STRAIN VS

Aim: The emergence of drug-resistant pathogens enforces the isolation of potent and novel antibiotic-producing Streptomyces sp., from the undisclosed ecological niches. Methodology: Unique Streptomyces violascens strain VS isolated by serial dilution agar plate method and strain confirmed by 16S rDNA sequencing. Antibacterial assay against multidrug resistant Pseudomonas aeruginosa isolated from bronchoalveolar lavage fluid was documented by primary (cross streak method) and secondary screening (agar well diffusion assay). Antibiotics are purified by organic solvent extraction, column chromatography, and thin-layer chromatography. The MIC and MBC value of antibiotics is determined against the pathogen by tube dilution method. Results: Fourteen Streptomyces species were isolated from Erode district, Tamil Nadu, with six different soil samples. Among the isolated Streptomyces sp., AC01 exhibited stable antibacterial activity against the MDR strain both in primary and secondary screening. It produced an opulent growth of powdery white colonies with yellow colour spores arranged in chains. Based on 16S rDNA sequencing, the isolated identified as Streptomyces violascens strain VS. Crude antibiotic was extracted from ISP-2 broth by ethyl acetate extraction and further purified by column chromatography with chloroform: methanol as solvent. Collected 3^rd fraction, validated for maximum antibacterial activity by bioautography. MIC concentrations of antibiotics are determined as 1250 µg/ml and MBC as 2500 µg/ml. Interpretation: The novel antibiotic produced by the S. violascens strain vs would be a promising drug to combat multidrug-resistant P. aeruginosa.