Antibacterial, cytotoxic and trypanocidal activities of marine-derived fungi isolated from Philippine macroalgae and seagrasses

The occurrence and bioactivities of marine-derived fungi are evaluated in this paper. A total of 16 morphospecies of marine-derived fungi (MDF) were isolated from four host macroalgae and two seagrasses and identified as belonging to the genera Aspergillus, Fusarium, Paecilomyces, Penicillium, Sclerotinia, Thamnidium and Trichoderma, including five mycelia sterilia. Among these host organisms, the rhodophyte Laurencia inter-media harboured the highest number of isolated MDF. Selected MDF were then assayed and showed to inhibit Pseudomonas aeruginosa (8-19 mm zone of inhibition) and Staphylococcus aureus (6-19 mm zone of inhibition), and were cytotoxic against the brine shrimp Artemia salina nauplii (LD50: 201.56-948.37 mu g mL(-1)). The screening led to the selection of five of the most bioactive morphospecies, all belonging to the genus Aspergillus. These marine aspergilli were subjected to beta-tubulin gene sequence analysis for species identification, and to mass production in different culture media with or without marine salts, and screening of the crude culture extracts for their cytotoxic and trypanocidal activities. Aspergillus tubingensis cultivated in potato dextrose broth with marine salt proved to be the most cytotoxic against P388 (IC50: 1028 ng mL(-1)) and HeLa (IC50: 1301 ng mL(-1)) cancer cells. On the other hand, A. fumigatus cultivated in malt extract broth without marine salt was shown to be the most potent against Trypanosoma congolense (IC50: 298.18 ng mL(-1)). Our study therefore showed that salinity may influence the bioactivities of some species of MDF.