Westerdykella reniformis Ebead & Overy sp. nov. is described based on morphology and phylogenetic analyses using ITS, nLSU rDNA, and β-tubulin gene sequences. Westerdykella reniformis is characterized by the production of cleistothecioid ascomata, containing small globose to subglobose asci with 32, aseptate, dark colored, pronouncedly reniform ascospores having a concave central groove. The isolate was obtained from a red alga (Polysiphonia sp.) collected from the tidal zone in Canada at low tide. Organic extracts enriched in extrolites, obtained from fermentation on a rice-based media, inhibited the growth of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), S. warneri, and Proteus vulgaris. Presented here is the identification of the compounds responsible for the observed antimicrobial activity, the taxonomic description of W. reniformis, and a dichotomous key to the known species of Westerdykella based on macro- and micromorphological characters.

To expand the potential of pseudopterosins and seco-pseudopterosins isolated from the octocoral Pseudopterogorgia elisabethae of San Andrés and Providencia islands (southwest Caribbean Sea), we report the anti-microbial profile against four pathogenic microorganisms (Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans) and report a more complete cytotoxic profile against five human cells lines (HeLa, PC-3, HCT116, MCF-7 and BJ) for the compounds PsG, PsP, PsQ, PsS, PsT, PsU, 3-O-acetyl-PsU, seco-PsJ, seco-PsK and IMNGD. For the cytotoxic profiles, all compounds evaluated showed moderate and non-selective activity against both tumor and normal cell lines, where PsQ and PsG were the most active compounds (GI₅₀ values between 5.8 µM to 12.0 µM). With respect to their anti-microbial activity the compounds showed good and selective activity against the Gram-positive bacteria, while they did not show activity against the Gram-negative bacterium or yeast. PsU, PsQ, PsS, seco-PsK and PsG were the most active compounds (IC₅₀ 2.9–4.5 µM) against S. aureus and PsG, PsU and seco-PsK showed good activity (IC₅₀ 3.1–3.8 µM) against E. faecalis, comparable to the reference drug vancomycin (4.2 µM).

Due to a rate increase in the resistance of microbial pathogens to currently used antibiotics, there is a need in society for the discovery of novel antimicrobials. Historically, fungi are a proven source for antimicrobial compounds. The main goals of this study were to investigate the fungal diversity associated with sea foam collected around the coast of Prince Edward Island and the utility of this resource for the production of antimicrobial natural products. Obtained isolates were identified using ITS and nLSU rDNA sequences, fermented on four media, extracted and fractions enriched in secondary metabolites were screened for antimicrobial activity. The majority of the isolates obtained were ascomycetes, consisting of four recognized marine taxa along with other ubiquitous genera and many ‘unknown’ isolates that could not be identified to the species level using rDNA gene sequences. Secondary metabolite isolation efforts lead to the purification of the metabolites epolones A and B, pycnidione and coniothyrione from a strain of Neosetophoma samarorum; brefeldin A, leptosin J and the metabolite TMC-264 from an unknown fungus (probably representative of an Edenia sp.); and 1-hydroxy-6-methyl-8-hydroxymethylxanthone, chrysophanol and chrysophanol bianthrone from a Phaeospheria spartinae isolate. The biological activity of each of these metabolites was assessed against a panel of microbial pathogens as well as several cell lines.

Dandruff, a skin disorder affecting 50% of the world population, is linked with proliferation of lipophilic yeasts of the genus Malassezia (particularly Malassezia globosa and M. restricta). Most Malassezia species show a unique lipid dependency and require external lipids for growth. Genome mining of the incomplete M. restricta genome led to the identification of eight lipase sequences. Sequences representing the class 3 and LIP lipase families were used to clone the lipases MrLip1, MrLip2 and MrLip3, recombinantly expressed in Pichia pastoris, and tested for their activity using mono-, di- and triacylglycerol substrates. Hydrolysis by the M. restricta lipase MrLip1 and MrLip2 (family class 3) was limited to the mono- and diacylglycerol, while MrLip3 (family LIP) hydrolyzed all three substrates. This result confirms that Malassezia family LIP lipases are responsible for the hydrolysis of triacylglycerols, the main component of human sebum. Furthermore, the information regarding lipases from M. restricta presented here might aid in the search for anti-dandruff agents.

The discovery of new natural products from fungi isolated from the marine environment has increased dramatically over the last few decades, leading to the identification of over 1000 new metabolites. However, most of the reported marine-derived species appear to be terrestrial in origin yet at the same time, facultatively halo- or osmotolerant. An unanswered question regarding the apparent chemical productivity of marine-derived fungi is whether the common practice of fermenting strains in seawater contributes to enhanced secondary metabolism? To answer this question, a terrestrial isolate of Aspergillus aculeatus was fermented in osmotic and saline stress conditions in parallel across multiple sites. The ex-type strain of A. aculeatus was obtained from three different culture collections. Site-to-site variations in metabolite expression were observed, suggesting that subculturing of the same strain and subtle variations in experimental protocols can have pronounced effects upon metabolite expression. Replicated experiments at individual sites indicated that secondary metabolite production was divergent between osmotic and saline treatments. Titers of some metabolites increased or decreased in response to increasing osmolite (salt or glycerol) concentrations. Furthermore, in some cases, the expression of some secondary metabolites in relation to osmotic and saline stress was attributed to specific sources of the ex-type strains.