''Epicoccum nigrum'' is a species of

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

in the phylum

Ascomycota Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The def ...

. A

plant pathogen Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomyc ...

and

endophyte An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; h ...

, it is a widespread fungus which produces coloured

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

s that can be used as antifungal agents against other pathogenic fungi. The fluorescent stain

epicocconone Epicocconone is a long Stokes shift, Stokes' shift Fluorophore, fluorescent dye found in the fungus ''Epicoccum nigrum''. Though weakly fluorescent in water (green emission, 520 nanometer, nm) it reacts Reversible reaction, reversibly with prote ...

is extracted from it.

Growth and morphology

''Epicoccum nigrum'' (1825) is a fungus with no known teleomorph form. It has been classified as a member of the

Hyphomycetes Hyphomycetes are a form classification of fungi, part of what has often been referred to as fungi imperfecti, Deuteromycota, or anamorphic fungi. Hyphomycetes lack closed fruit bodies, and are often referred to as moulds (or molds). Most hyph ...

, in the Deuteromycota, as well as the

Fungi Imperfecti The fungi imperfecti or imperfect fungi, are fungi which do not fit into the commonly established taxonomic classifications of fungi that are based on biological species concepts or morphological characteristics of sexual structures because the ...

because it is only known to reproduce asexually. Despite that it is not yeast-like, it has been included in the broad, unrelated category of fungi known as

black yeast “Black yeasts”, sometimes also black fungi, dematiaceous fungi, microcolonial fungi or meristematic fungi is a diverse group of slow-growing microfungi which reproduce mostly asexually ( fungi imperfecti). Only few genera reproduce by budding ...

s. The fungus grows felty colonies in bright shades of yellow, orange, and red, often with brown or black throughout. Colonies grow quickly, reaching about 6 cm in diameter in 2 days at room temperature. Mycelia contain both chitin and cellulose. ''Epicoccum nigrum'' forms blastoconidia that are darkly coloured, warted and spherical, reaching 15 to 25 µm in diameter. Conidia grow on a sporodochium, formed by warty and fibrous

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

e. Sporets have been found to contain up to 15 cells. The spores of ''E. nigrum'' are actively released depending on temperature, light, and relative humidity conditions. The mechanism of release involves the separation of the conidium from the sporodochium via a double septum. It capitalizes on the spherical shape of the conidia, allowing it to "bounce" off the sporodochium. Conidia then become airborne with movement or wind. Sporulation is induced under Wood's light, or sometimes upon exposure to cold temperatures with a subsequent return to room temperature. Pigment production is also sensitive to light and temperature changes. Ideal growth temperatures range between , and ideal growth pH ranges from 5.0 to 6.0. Although ''E. nigrum'' will grow in a range of water activity (aw of 0.99 to 0.97), growth is optimized at water vapour saturation. ''Epicoccum nigrum'' produces a variety of biomedically and industrially useful metabolites, including important antifungal agents and pigments, including: flavipin, epicorazines A and B, epirodin,

, and a variety of carotenoid pigments. ''Epicoccum nigrum'' has also been utilized in the biosynthetic manufacture of silver- and gold nanoparticles.

Habitat and ecology

A highly robust and ubiquitous fungus, ''E. nigrum'' has an almost global spread, occurring in the Americas, Asia, and Europe. Spores of ''E. nigrum'' have been cultured from a variety of environments, predominantly soil (i.e. peat, forest floor, raw humus, compost, tundra, sewage) and sand (e.g., dunes, saline sands). It is a saprophytic fungus, forming pustules (composed of sporodochia and conidia) on dead and dying plants. This species is commonly found growing on cereals and seeds, as well as other crops including corn, beans, potatoes, peas and peaches. It has been found to grow colonies on leaves submersed in water as cold as , and is considered a facultative marine fungus. It is capable of colonizing algae and marsh grasses. In indoor environments, ''E. nigrum'' has been found on paintings and wallpaper, cotton and textiles, in dust, and in air. It is tolerant of changes in water availability, and hyphal growth has been found to resume within an hour of exposure to water.

Biomedical, industrial, and agricultural uses

''Epicoccum nigrum'' has a wide array of medical, industrial, and agricultural applications. It produces a variety of pigmented and non-pigmented antifungal and antibacterial compounds. These antimicrobial compounds are effective against other fungi and bacteria present in soil. Flavipin, and epirodins A and B are pigmented antifungal agents; non-pigmented compounds include epicorazines A and B. Endophytic fungi such as ''E. nigrum'' are being explored as alternative sources of antibiotics to treat important resistant infections. Polysaccharide antioxidants are also produced by ''E. nigrum''. Epicocconone is a fluorescent pigment unique to ''E. nigrum''. Epicocconone is valuable in terms of its ability to pigment cells orange, which then fluoresce red without impacting cell structure or function. Industrially, ''E. nigrum'' has a variety of broad applications. It has demonstrated a capacity to biosynthesize nanoparticles from silver and gold, which have applications in chemical, industrial, and medical processes. It has been applied as biological treatment for mechanical oily effluent, reducing the content of

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%� ...

, phenols, and chemical oxygen demand in the oily effluent. ''Epicoccum nigrum'' pigments have been considered as natural replacements for artificial pigments currently used in food. It produces a variety of pigments, ranging from darker oranges to yellows and greens. These pigments were synthesized by nonpathogenic strains of ''E. nigrum''. In Brazil, ''E. nigrum'' is used to support root growth and control sugarcane pathogens. It is a biocontrol antifungal agent active against brown rot in stone fruit, caused the species ''

Monilinia laxa ''Monilinia laxa'' is a plant pathogen that is the causal agent of brown rot of stone fruit In botany, a drupe (or stone fruit) is an indehiscent fruit in which an outer fleshy part ( exocarp, or skin, and mesocarp, or flesh) surrounds a ...

'' and '' Monilinia fructigena''. In contrast to these uses for ''E. nigrum'' metabolites, there has been an investigation into methods of controlling ''E. nigrum'' fungal colonies that have contaminated historic and cultural artifacts. The fungus was found to be quite sensitive to essential oils from plants such as

lavender ''Lavandula'' (common name lavender) is a genus of 47 known species of flowering plants in the mint family, Lamiaceae. It is native to the Old World and is found in Cape Verde and the Canary Islands, and from Europe across to northern and easte ...

and

rosemary ''Salvia rosmarinus'' (), commonly known as rosemary, is a shrub with fragrant, evergreen, needle-like leaves and white, pink, purple, or blue flowers, native plant, native to the Mediterranean Region, Mediterranean region. Until 2017, it was kn ...

. This is important in terms of the preservation of artifacts in humid climates, where fungal growth is an important determinant in the deterioration of stone structures and wood frames.

Epidemiology

''Epicoccum nigrum'' produces the glycoprotein allergen Epi p 1 which binds to IgE, sometimes cross-reacting with other fungal allergens. Cross-reactivity was found to exist with ''Alternaria alternata'', ''Curvularia lunata'', ''Cladosporium herbarum'', and ''Penicillium citrinum''. ''Epicoccum nigrum'' is associated with respiratory fungal allergies, including allergic asthma, rhinitis, hypersensitivity pneumonitis, and allergic fungal sinusitis. Two pediatric cases of

hypersensitivity pneumonitis Hypersensitivity pneumonitis (HP) or extrinsic allergic alveolitis (EAA) is a syndrome caused by the repetitive inhalation of antigens from the environment in susceptible or sensitized people. Common antigens include molds, bacteria, bird dropping ...

caused by ''E. nigrum'' were reported in children living in a damp and mouldy home, with daily exposure to ''E. nigrum'' in the shower. The fungus has been found on human skin and in spit samples. It does not typically cause systemic infection, although one case has been reported in an immunocompromised patient.

History and reclassification

''Epicoccum nigrum'' has been treated under a variety of names in the genus ''Epicoccum''. It was first identified in 1815 by botanist Johaan Heinrich Friedrich Link. Today, all previously identified species are considered to be different variants of the species ''E. nigrum''. These include: ''E. purpurascens'', ''E. diversisporum'', ''E. versicolor'', ''E. vulgare'', ''E. granulatum'', ''E. menispermi'', and ''E. neglectum''. More recently, two distinct genotypes for ''E. nigrum'' have been identified with the combined use of DNA sequencing, morphology, physiology, and recombination factors. This indicates the existence of cryptic species, and a subsequent call to re-classify ''E. nigrum'' into more than one species.

References

{{DEFAULTSORT:Epicoccum nigrum Pleosporales Fungal plant pathogens and diseases Fungi described in 1816