Different marine habitats support very different fungal communities. Fungi can be found in niches ranging from ocean depths and coastal waters to mangrove swamps and estuaries with low salinity levels. Marine fungi can be saprobic or parasitic on animals, saprobic or parasitic on algae, saprobic on plants or saprobic on dead wood.
Marine fungi produce antiviral and antibacterial compounds as metabolites with upwards of 1,000 having realized and potential uses as anticancer, anti-diabetic, and anti-inflammatory drugs.
The antiviral properties of marine fungi were realized in 1988 after their compounds were used to successfully treat the H1N1 flu virus. In addition to H1N1, antiviral compounds isolated from marine fungi have been shown to have virucidal effects on HIV, herpes simplex 1 and 2, Porcine Reproductive and Respiratory Syndrome Virus, and Respiratory Syncytial Virus. Most of these antiviral metabolites were isolated from species of Aspergillus, Penicillium, Cladosporium, Stachybotrys, and Neosartorya. These metabolites inhibit the virus’s ability to replicate, thereby slowing infections.
Mangrove-associated fungi have prominent antibacterial effects on several common pathogenic human bacteria including, Staphylococcus aureus and Pseudomonas aeruginosa. High competition between organisms within mangrove niches lead to increases in antibacterial substances produced by these fungi as defensive agents. Penicillium and Aspergillus species are the largest producers of antibacterial compounds among the marine fungi.
Various deep-sea marine fungi species have recently been shown to produce anti-cancer metabolites. One study uncovered 199 novel cytotoxic compounds with anticancer potential. In addition to cytotoxic metabolites, these compounds have structures capable of disrupting cancer-activated telomerases via DNA binding. Others inhibit the topoisomerase enzyme from continuing to aid in the repair and replication of cancer cells.