chrysosporium

Chrysosporium is a genus of filamentous fungi in the phylum Ascomycota, order Onygenales. It comprises numerous species that are typically hyaline (light-colored) and keratinophilic, capable of growing on keratin-rich substrates such as soil enriched with hair or feathers.

Morphology and physiology commonly include hyaline, septate hyphae and the production of small conidia. Many Chrysosporium species form microconidia on slender conidiophores, and some also produce thick-walled resting cells known as chlamydospores. On standard culture media, colonies are usually white to yellowish and can have a powdery or cottony appearance. Growth rates vary among species.

Ecology and distribution features show that Chrysosporium species are widely distributed in soil, detritus, and keratin-rich environments. They are primarily saprotrophs that contribute to keratin degradation but can also be isolated from animal-derived materials such as feathers and hair. Several species have been recovered from clinical specimens and are regarded as opportunistic pathogens, particularly in immunocompromised individuals.

Taxonomy and phylogeny have been complex. Chrysosporium historically served as a catchall for diverse keratin-degrading molds, but molecular studies have led to reclassification of many species into other genera within Onygenales or as anamorphs of dermatophytes. Notably, some Chrysosporium species are recognized as anamorphs of reptile-associated pathogens (for example, Chrysosporium anamorphs of Nannizziopsis vriesii).

Clinical relevance is generally limited to opportunistic infections of the skin, nails, or occasionally the lungs, primarily in susceptible hosts. Accurate identification often requires molecular methods.

See also: Dermatophyte, Onygenales.