Antimicrobial activity of secondary metabolite from marine isolate, Pseudomonas sp. against Gram positive and negative bacteria including MRSA.

A proteobacterium isolated from coastal region of Chennai, India, produced appreciable secondary metabolite and partial purification of the obtained secondary metabolite demonstrated antimicrobial activity against both Gram positive and negative organisms including MRSA (methicillin resistant Staphylococcus aureus). Identification of the isolate using biochemical tests, 16s rDNA sequence analysis, G+C content and electron microscopy studies revealed, isolate belonged to Pseudomonas genera. Extraction, purification, characterization and antimicrobial activity of secondary metabolite carried out using various standard instrumental techniques suggested that the active fraction was of 272 m/z with a stable fragment of 244 m/z and also displayed stable free radical activity assessed using EPR analysis. This stable free radical activity of secondary metabolite mediated its antimicrobial activity.