Cryptococcus Neoformans - Characteristics

Characteristics

Cryptococcus neoformans grows as a yeast (unicellular) and replicates by budding. C. neoformans makes hyphae during mating, and eventually creates basidiospores at the end of the hyphae before producing spores. Under host-relevant conditions, including low glucose, serum, 5% carbon dioxide, and low iron, among others, the cells produce a characteristic polysaccharide capsule. 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 in cerebral spinal fluid. 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. This allows for quick and easy identification of C. neoformans. For identification in tissue, Mucicarmine stain provides specific staining of polysaccharide cell wall in Cryptococcus neoformans.

C. neoformans grows rapidly on exposure to radiation such as gamma-radiation. Radiation seems to increase the electron-transfer capability of melanin in the fungus, increasing its total metabolic activity.