Unveiling Biological Activities of Marine Fungi: The Effect of Sea Salt

Abstract

There is an urgent need for new substances to overcome current challenges in the health sciences. Marine fungi are known producers of numerous compounds, but the manipulation of growth conditions for optimal compound production can be laborious and time-consuming. In Portugal, despite its very long coastline, there are only a few studies on marine fungi. From a collection of Portuguese marine fungi, we screened for antimicrobial, antioxidant, enzymatic, and cytotoxic activities. Mycelia aqueous extracts, obtained by high pressure-assisted extraction, and methanolic extracts of culture media showed high antioxidant, antimicrobial, and cytotoxic activities. The mycelium extracts of Cladosporium rubrum showed higher antioxidant potential compared to extracts from other fungi. Mycelia and culture media extracts of Aspergillus affinis and Penicillium lusitanum inhibited the growth of Staphylococcus aureus, Kocuria rhizophila, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa, including multiresistant strains. Penicillium lusitanum and Trichoderma aestuarinum inhibited the growth of clinical strains of Candida albicans, C. glabrata, C. parapsilosis, and C. tropicalis. All extracts from culture media were cytotoxic to Vero cells. Sea salt induced alterations in the mycelium’s chemical composition, leading to different activity profiles.

Genomic and Metabolomic Analyses of the Marine Fungus Emericellopsis cladophorae: Insights into Saltwater Adaptability Mechanisms and Its Biosynthetic Potential

“…laurentii), thus indicating its ability act against aspergillosis and cryptococcosis [8]. In a recent study, Gonçalves et al [18] did not observe antifungal activity against Candida spp. in E. cladophorae extracts, a close relative to E. alkalina [7].…”

“…A small-scale fermentation was carried out as described by Gonçalves et al [18]. Briefly, two plugs of mycelium-colonized agar were inoculated into 1-L Erlenmeyer flasks containing 250 mL of PDB in two conditions: with and without 3% sea salt (Sigma-Aldrich, Darmstadt, Germany) with 4 replicates for each condition.…”

“…Due to the lack of information on the MS databases (1 inhouse library and MoNA), many of these compounds remain unidentified. We had already suggested [18] that sea salt induces an alteration to the metabolic profile of E. cladophorae. For example, the compounds ions annotated as ergocryptine, 2'-O-Galloylhyperin, (-)-Gallocatechin 3-gallate, N-[1-(4-methoxy-6-oxopyran-2-yl)-2-methylbutyl] acetamide, ferulic acid ethyl ester, 6-Methoxymethylone, 3'-O-Methylguanosine, heptanedioic acid, melezitose, salicylic acid, 5-Sulfosalicylic acid, N4-Acetylsulfadiazine, 5'-Iodoresiniferatoxin, and tafluprost acid were more abundant in salted medium.…”

“…The observed effects may be related to the fermentation culture conditions or extractions methods. Kuvarina et al [8] used an alkaline medium (pH 10.5) containing malt and yeast extract with ethyl acetate as solvent to obtain the crude extracts, while Gonçalves et al [18] used PDB and methanol. Additionally, Hagestad et al [22] used 11 different fermentation culture media and observed different bioactivities profiles, indicating the likelihood of expression of different compounds.…”

“…at the estuary Ria de Aveiro, Portugal, during the summer of 2018 [7]. Crude extracts from E. cladophorae have antibacterial, antioxidant and cytotoxic properties [18]. Moreover, it was shown that E. cladophorae strain MUM 19.33 produces proteinases, cellulases, chitinases, pectinases, pectin lyases and ureases, among other enzymatic activities.…”