Ramesh Subramani and William Aalbersberg
Keywords: LC-MS profile, microbial metabolites, bioassay guided isolation, marine actinomycetes, bioactive compounds
Abstract: A total of 29 marine actinomycetes were isolated of which more than 75% showed potent antibacterial (MRSA; methicillin-resistant Staphylococcus aureus, VREF; vancomycin-resistant Enterococcus faecium) activity and 3% displayed anti fungal (ARCA; amphotericin-resistant Candida albicans, WTCA; wild type Candida albicans) activity against human drug-resistant pathogens. However all the strains (100%) exhibited cytotoxicity against brine shrimp larvae. All the crude extracts injected in the time-of-flight liquid chromatography mass spectrometry (HRESI-LC-MS) to analyse the metabolites profile with the respective UV profiles, molecular masses and the data were verified using natural product database, AntiBase and in-house database for screening of new compounds. Stauroporine, halomycin, rifamycin and their derivatives are commonly found in the microbial extracts. However, an actinomycete strain F-1568showed a unique profile with two derivatives of compounds have an UV profile similar to mycinamicin but had a different molecular mass, while another peak had an distinct UV profile but did not match any compounds in the in-house database revealing that F-1568 is a promising candidate for the discovery of new bioactive compounds
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