Diversity of marine fungi isolated from selected scleractinian corals and their secondary metabolites / Lee Li Chuen

Lee , Li Chuen (2021) Diversity of marine fungi isolated from selected scleractinian corals and their secondary metabolites / Lee Li Chuen. Masters thesis, Universiti Malaya.

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Abstract

Scleractinian corals (also known as hard corals) are organisms comprised of colonies polyps that harbor assemblage of microbes, known collectively as coral holobionts which comprises of algae, bacteria, virus, fungi and archaea. Despite the prevalence of coral fungi, not much is known regarding their role and interaction with its host, especially their secondary metabolites aspect. The marine environment hosts fungal community with a contrasting metabolic profile as compared to its terrestrial counterparts. In current study, a total of 31 marine fungi has been isolated from eight scleractinian corals. Penicillium and Neodevriesia both frequently occurred in the collected scleractinian corals. Using multigene phylogeny approaches, selected strains were identified as Colletotrichum siamense (from Porites sp2) and Neodevriesia sp. 4 (from Galaxea astreata) for studies of their secondary metabolites. Fungal strains were cultured in potato dextrose broth for 30 days and mycelium were filtered and macerated in methanol. Methanol extract were further partitioned with ethyl acetate and water. Ethyl acetate extract were undergone further purification using column chromatography and preparative thin-layered chromatography to isolate secondary metabolites. Partially purified isolates were evaluated using NMR and methylated lipid layers were analysed for fatty acid composition. Investigated strains of fungus showed contrasting FAME profiles making it potential identification markers to fungus. Crude extracts and fractions of C. siamense were inactive against bacterial strains. 1H- NMR results showed that majority of the fatty acids isolated are variation of very-long-chained fatty acids.

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