Epipyrone A, a Broad-Spectrum Antifungal Compound Produced by Epicoccum nigrum ICMP 19927

Abstract

We have isolated a filamentous fungus that actively secretes a pigmented exudate when growing on agar plates. The fungus was identified as being a strain of Epicoccum nigrum. The fungal exudate presented strong antifungal activity against both yeasts and filamentous fungi, and inhibited the germination of fungal spores. The chemical characterization of the exudate showed that the pigmented molecule presenting antifungal activity is the disalt of epipyrone A—a water-soluble polyene metabolite with a molecular mass of 612.29 and maximal UV–Vis absorbance at 428 nm. This antifungal compound showed excellent stability to different temperatures and neutral to alkaline pH.

Fungi Detected in the Previous Year’s Leaf Petioles of Fraxinus excelsior and Their Antagonistic Potential against Hymenoscyphus fraxineus

“…Coniochaeta species produce antibacterial and antifungal coniosetin and coniochaetone-a and -b [147]. The frequently found E. nigrum produces flavipin, epicorazine and epipyrone A [145,148]. The antifungal activities of some of them has led to development of biological control products based on E. nigrum mycelium, spores and metabolites [148].…”

“…The frequently found E. nigrum produces flavipin, epicorazine and epipyrone A [145,148]. The antifungal activities of some of them has led to development of biological control products based on E. nigrum mycelium, spores and metabolites [148]. Moreover, this species secretes cell-wall degrading enzymes which contribute to lysis of pathogen hyphae.…”

Fungal Guttation, a Source of Bioactive Compounds, and Its Ecological Role—A Review

“…The examples mentioned above do not cover all of the reports. Other works describe antifungal polyene compounds [ 32 , 33 ], unidentified substances that likely grant fungitoxicity to exudates [ 25 , 27 ], or accompanying constituents, such as some fatty acids, that are not discussed here [ 17 ].…”

A secondary metabolite drives intraspecies antagonism in a gut symbiont that is inhibited by cell-wall acetylation

“…As a class of PKS products, aryl polyenes are lipids with an aryl head group conjugated to a polyene tail (Lin et al, 2015) and are widely distributed in soil and host-associated bacteria (Cimermancic et al, 2014;Youngblut et al, 2020). Although, many polyene compounds isolated from terrestrial and marine microbes possess antimicrobial effects in vitro (Herbrı ´k et al, 2020;Lee et al, 2020;Li et al, 2021;Zhao et al, 2021), virtually nothing is known about their ecological role in microbe-host and microbemicrobe interactions in the mammalian gastrointestinal tract (Aleti et al, 2019). While metagenome studies are critically important to identify novel polyene-like BGCs within the microbiome (Hiergeist et al, 2015;Medema et al, 2011), the assessment of model organisms and their isogenic mutants in the appropriate ecological context is critical to advance our knowledge on the biological function of these BGC-derived compounds.…”