Growth and biofilm formation potential of Malassezia species in an in vitro artificial sebum model

Summary: <i>Malassezia</i> yeast overgrowth is linked to multiple skin disorders, yet its growth dynamics and virulence traits remain poorly understood. This study aimed to evaluate the growth, biofilm formation, and virulence potential of <i>Malassezia</i> species using an optimized<i> in vitro</i> artificial sebum model that closely mimics sebum-rich skin conditions. The model was specifically adapted to support <i>Malassezia</i> growth by modifying the pellet composition. Biofilm formation was assessed using confocal microscopy with Calcofluor and FUN1 staining to visualize cell wall structures and metabolic activity, while growth was quantified via conventional plating and quantitative PCR. Multiple <i>Malassezia</i> species, including <i>M. furfur,</i> <i>M. pachydermatis</i>, <i>M. sympodialis</i>, and <i>M. restricta,</i> demonstrated robust growth and biofilm formation. Indole production and extracellular lipase activity were also examined, though results were inconclusive. This study introduces a tailored <i>in vitro</i> artificial sebum model for <i>Malassezia</i> biofilm research, providing a valuable tool for studying its growth dynamics and potential role in skin disorders. Britta De Pessemier¹, Merel Verdonck¹, Karl-Jan Spittaels¹, Yorick Minnebo¹, Tom Coenye², Tom Van de Wiele¹, Chris Callewaert¹ 1. Bioscience Engineering - CMET, Universiteit Gent, Ghent, Flanders, Belgium. 2. Department of Pharmaceutical Analysis - LPM Laboratory of Pharmaceutical Microbiology, Universiteit Gent, Ghent, Flanders, Belgium. Innate Immunity, Microbiology, and Microbiome