A dimorphic fungus is a fungus that can exist in the form of both mold[1] and yeast. As this is usually brought about by a change in temperature, this fungus type is also described as a thermally dimorphic fungus.[2] An example is Talaromyces marneffei,[3] a human pathogen that grows as a mold at room temperature, and as a yeast at human body temperature.
The term dimorphic is commonly used for fungi that can grow both as yeast and filamentous cells, however many of these dimorphic fungi actually can grow in more than these two forms. Dimorphic is thus often used as a general reference for fungi being able to switch between yeast and filamentous cells, but not necessary limiting more shapes.[4][a]
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!
Notes
^ abcdefghe.g. Candida albicans, Paracoccidioides brasiliensis, Sporothrix schenckii, Histoplasma capsulatum and Coccidioides immitis are commonly referred to as being dimorphic, however they can be seen as pleomorphic or polyphenic as they can adopt more morphologies than just yeast or filamentous cells.[8][4]
^ abSánchez-martínez, Cristina; Pérez-martín, José (2001). "Dimorphism in fungal pathogens: Candida albicans and Ustilago maydis—similar inputs, different outputs". Current Opinion in Microbiology. 4 (2): 214–221. doi:10.1016/S1369-5274(00)00191-0. PMID11282479.
^Kenyon, Chris; Bonorchis, Kim; Corcoran, Craig; Meintjes, Graeme; Locketz, Michael; Lehloenya, Rannakoe; Vismer, Hester F.; Naicker, Preneshni; Prozesky, Hans; van Wyk, Marelize; Bamford, Colleen; du Plooy, Moira; Imrie, Gail; Dlamini, Sipho; Borman, Andrew M.; Colebunders, Robert; Yansouni, Cedric P.; Mendelson, Marc; Govender, Nelesh P. (2013). "A Dimorphic Fungus Causing Disseminated Infection in South Africa". New England Journal of Medicine. 369 (15): 1416–1424. doi:10.1056/NEJMoa1215460. ISSN0028-4793. PMID24106934. S2CID15865.