Isolation, Screening, Statistical media optimization, Purification and Structural characterization of bioactive compound from marine derived Streptomyces sp JS-S6

Exploitation and overuse of antibiotics in the health sectors leads to the development of resistance mechanism in microbes against antibiotics. As a consequence, there is a vital need to develop effective lead compound from natural sources. Compounds derived from marine habitat have a remarkable nature of unique chemical structures and exhibit bioactivity, so it can be used in the treatment against antibiotic resistant clinical pathogens. The present study was mainly focused on isolation and screening of novel Streptomyces species against clinical pathogens from unexplored marine environment. In this study, thirty five actinomycetes isolates were identified. Among these, the isolate JS-S6 exhibits a strong antagonistic effect against the pathogens used. The 16S rRNA gene analysis of the isolate JSS6 showed that it was similar to Streptomyces viridobrunneus LMG20317 and named as Streptomyces sp JS-S6. The Scanning Electron Microscopy (SEM) studies revealed that the spores were highly abundant, irregular in shape and distributed unequally. One Factor at a time (OFAT) medium optimization revealed that starch, ammonium sulphate and seven days of incubation period as efficient factor to emphasis the maximum biomass production and highest antibacterial activity. Placket Burman method and central composite design of response surface methodology in statistical media optimization disclosed the significant factors were starch, ammonium sulphate and Sodium chloride and their optimum concentration were 1%, 0.2% and 0.1 % respectively for maximum biomass production and antibacterial activity. Mass fermentation was carried out with optimized medium and purification of crude extract was done by silica column chromatography. The UV-Visible spectroscopy analysis showed that the compound has maximum absorption at 260.0 nm and FTIR analysis revealed the presence of methoxy functional group. The GC-MS analysis also strongly suggest that the bioactive metabolite was found to be Methyl Nhydroxybenzenecarboximidate (Oxime-Methoxy phenyl compound) when compared with mass spectra of Wiley and NIST95 database. The compound exhibited strong antibacterial activity against clinical pathogens without exhibiting cytotoxicity potential against H9C2 cell line. From this study it was clear that the bioactive compound from Streptomyces sp. JS-S6 have antibacterial activity against clinical pathogens. In future, it can be developed as potential lead molecule against pathogens that develop resistance against antibiotics.