Differential lipase virulence in Malassezia furfur dimorphism isolated from pityriasis versicolor patients and healthy individuals

Background: Malassezia furfur is a member of the human skin microbiomes that can cause various skin diseases. Dimorphism plays a role as the yeast phase predominates during skin colonisation whereas mycelial forms are observed in the scales of patients with pityriasis versicolor (PV). However, due to their condition-dependence for growth, it is difficult to culture M. furfur and this is an additional challenge for studying the pathogenicity of this fungus. Objective: To describe different media suitable for culturing Malassezia from the yeast phase into mycelial forms, with a particular focus on nutritional supplements and pH conditions. Methods: Clinical M. furfur isolates from patients with PV and healthy individuals were used to investigate Malassezia dimorphism as well as the activity and expression of lipase enzymes. Results: Our experimental media were significantly more likely to promote mycelial growth in strains from healthy individuals compared to those from patients with PV. Lipase activity was increased in the mycelial phase cells compared to yeast forms for all strains tested. Assessment of the relative transcriptional expression of lipase within M. furfur revealed that LIP-coding genes were upregulated in mycelium relative to yeast forms for the strains tested. However, the increases in LIP3, LIP5 and LIP6 gene expressions were significantly greater in strains from healthy individuals compared to those from patients with PV. Conclusion: Overall, this study validated effective growth conditions to study M. furfur virulence factors and demonstrated that lipase is associated with M. furfur dimorphism.