Polymorphism of Malassezia furfur

Area of Science:

• Medical Mycology
• Microbial Physiology

Background:

• Pityrosporum orbiculare and Pityrosporum ovale are yeasts often associated with human skin conditions.
• Their distinct morphologies and physiological characteristics have led to their classification as separate species.

Purpose of the Study:

• To investigate the morphological and physiological plasticity of Pityrosporum orbiculare isolates.
• To determine if P. orbiculare and P. ovale represent different life cycle stages of a single fungal species.

Main Methods:

• Prolonged maintenance of 11 P. orbiculare isolates in pure culture.
• Successive subculturing to observe morphological changes.
• Physiological characterization, including utilization of olive oil, Tween 20, and KNO3 as sole nutrient sources.

Main Results:

• Isolates progressively shifted from globose (P. orbiculare) to ovoid and then cylindrical (P. ovale) forms.
• Globose forms did not utilize olive oil or Tween 20, unlike ovoid and cylindrical forms.
• Ovoid and cylindrical forms showed varying abilities to assimilate nitrogen from KNO3.

Conclusions:

• Morphological and physiological changes suggest P. orbiculare and P. ovale are developmental stages of Malassezia furfur.
• Maintaining distinct nomenclature is recommended until the full life cycle is elucidated.