| || || Ragini, Kavita.|
| || || Isolation and characterisation of bioactive antibacterial compounds from an obligate marine actinomycete salinispora arenicola|
Institution: University of the South Pacific.
Call No.: pac In Process
Copyright:Under 10% of this thesis may be copied without the authors written permission
Abstract: The oceans cover 70% of the Earth’s surface and harbor most of the planets biodiversity. Recent studies have revealed that marine actinomycetes are a robust source of new natural products. Salinispora is the first obligate marine genus within the order Actinomycetales and a rich source of biologically active secondary metabolites. Members of this genus have proven to be of particular interest due to new chemical structures including the potent proteasome inhibitor salinosporamide A and other distinct groups are yielding new classes of terpenoids, amino acidderived metabolites and polyene macrolides. A Salinispora arenicola strain was isolated from a marine sediment and identified by 16S gDNA sequence. Four known compounds N-(2'-phenylethyl)isobutyramide, 2-methyl-N-(2'-phenylethyl)butyramide, N-(2'-phenylethyl)isovaleramide and rifamycin W were isolated from this strain. Compounds N-(2'- phenylethyl)isobutyramide, 2-methyl-N-(2'-phenylethyl)butyramide and N-(2'- phenylethyl)isovaleramide were determined by LC/MS and 1H NMR data. Structure elucidation of rifamycin W was established by detailed spectral analysis of LC/MS, 1H NMR, 13C NMR and 2D NMR. All the amides were found to be inactive against all the bacteria and fungi. Rifamycin W had a minimum inhibitory concentration (MIC) of 12.5μg/mL against methicillin resistant Staphylococcus aureus, 6.25μg/mL against wild type Staphylococcus aureus and above 250μg/mL against vancomycin resistant Enterococcus faecium. Rifamycin W was inactive against amphotericin B resistant and wild type Candida albicans. The analysis reported here demonstrates that this Salinispora arenicola isolate produces compounds of different classes. The Salinispora group, as a relatively newly discovered group of Actinobacteria, is one with great potential and its properties and products are only beginning to be explored. The continued development of improved spectral techniques and cultivation methods promises to provide access to significantly new sources of chemical diversity.