Dimorphic fungus

Candida albicans growing as yeast cells and filamentous (hypha) cells

Dimorphic fungi are fungi that can exist in the form of both mold^[1] and yeast. An example is Penicillium marneffei,^[2] a human pathogen that grows as a mold at room temperature, and as a yeast at human body temperature.

Ecology of dimorphic fungi

Several species of dimorphic fungi are important pathogens of humans and other animals, including Coccidioides immitis,^[3] Paracoccidioides brasiliensis,^[3] Candida albicans,^[4] Blastomyces dermatitidis, Histoplasma capsulatum, Sporothrix schenckii, and Emmonsia sp.^[5]

Many other fungi, including the plant pathogen Ustilago maydis^[4] and the cheesemaker's fungus Geotrichum candidum also have dimorphic life cycles.

Mnemonics

In medical mycology, these memory aids help students remember that among human pathogens, dimorphism largely reflects temperature:

• Mold in the Cold, Yeast in the Heat (Beast)
• Body Heat Probably (Changes) Shape
  • Blastomyces dermatitidis, Histoplasma capsulatum, Paracoccidioides brasiliensis, (Coccidioides immitis) is in parentheses because it changes to a spherule of endospores, not yeast, in the heat), Sporothrix schenckii.
  • This phrase says "Probably" because there is always an exception (in this case fungi like Candida albicans) which change in the opposite direction: to mold in the heat!

References