Cryptococcus neoformans
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Cryptococcus neoformans is an encapsulated yeastlike fungus that can live in both plants and animals. This species, also known by its teleomorph name, Filobasidiella neoformans, belongs to the broad class of organisms called "club fungi" or Division Basidiomycota, which is one the five major types of fungi. C. neoformans usually grows as a yeast (unicellular) and replicates by budding. Under certain conditions, both in nature and in the laboratory, C. neoformans can grow as a filamentous fungus as pictured here: picture of the organism Template:Ref. When grown as a yeast, C. neoformans has a prominent capsule composed mostly of polysaccharides. Microscopically, the India ink stain is used for easy visualization of the capsule. The particles of ink pigment do not enter the capsule that surrounds the spherical yeast cell, resulting in a zone of clearance or "halo" around the cells.
The species C. neoformans is composed of three variants (v.): C. neoformans v. gattii, v. grubii, and v. neoformans. C. neoformans v. gattii is found mostly in the tropics, but has also been confirmed on southern Vancouver Island on the southwestern coast of Canada. Cryptococcus gattii has recently been shown to be different enough from other subspecies to be elevated to its own species level. C. neoformans v. grubii and v. neoformans have a worldwide distribution and are often found in soil which has been contaminated by bird excrement. The genome sequence of C. neoformans v. neoformans was published in 2005.Template:Ref
Infection with C. neoformans is termed cryptococcosis.
Reference
- Template:Note Photomicrograph hosted by the Tree of Life project and specifically contributed by the Duke University Mycology Research Unit; the picture is part of the Hymenomycetes article. Retrieved 2005-03-15.
- Template:Note Loftus BJ et al. The genome of the basidiomycetous yeast and human pathogen Cryptococcus neoformans. Science 307(5713), 1321-1324. PMID 15653466.
- Casadevall A, Perfect JR, Cryptococcus neoformans, ASM Press, Washington, DC, 1998.