Marine- derived natural products are a rich source of potential new antibiotics and anticancer agents. Actinomycetes (order: Actinomycetales) are a best known source of antibiotics and account for almost 70% of the worlds naturally occurring antibiotics. Marine actinomycetes can be isolated from sediments around the Fiji waters. The sediments are collected using coring devices and further processes in the lab to isolate the actinomycetes onto M1 isolation media. Actinomycetes appear after 2-6 weeks and have a tough leathery texture, with dry or folded appearance and branching filaments. Isolates are cultured in shake flasks and subjected to small scale and large scale fermentation. Broth suspension is extracted with ethyl acetate and the ethyl acetate extract is removed and dried completely. The crude extract is tested for biological activity against Vancomycin-resistant Enterococcus faecium (VREF), Methicillin-resistant Staphylococcus aureus (MRSA) and wild type Staphylococcus aureus (WTSA) and Candida albicans (Wild-type WTCA and amphotericin B- resistant ARCA). The bioactive extracts are further subjected to chromatography techniques to isolate and elucidate the structures of the bioactive metabolites of Actinomycetes.
As part of our ongoing projects I am also involved in testing the biological activity of crude extracts from marine invertebrates/algae by determining if they have antibacterial or antifungal activity.