Affinity of Malassezia and other yeasts for pulmonary lipids

Pulmonary surfactant is the main substance that lines the epithelium of the human Lower Respiratory Tract (LRT). It has a high lipidic content, being dipalmitoyl-phosphatidylcholine (DPPC) the most abundant one. Although surfactants have a well-known antifungal activity for some yeast species, the important presence of species like Malassezia restricta in the lung mycobiome, leads to the idea that these yeasts may have some lipo-tolerance or even lipoaffinity for pulmonary lipids. A culture-based study of affinity and tolerance to pulmonary lipids by yeasts described as important members of the lung microbiome has been carried out. Ten species belonging to the genera Malassezia, Candida (including the new genera Nakaseomyces and Meyerozyma ) and Cryptococcus , were tested for their ability to grow on media containing pulmonary lipids such as DPPC and commercial porcine surfactant. Lipoaffinity or lipo-tolerance was considered on the basis of their growth on standard media, considered as such the Modified Leeman Notman Agar (MLNA) for Malassezia species, and the Sabouraud Dextrose Agar (SDA) for the other genera. The addition of DPPC or surfactant to the media assayed resulted in increased growth of Malassezia yeasts and one of the Cryptococcus species. C. parapsilosis showed similar growth to the one obtained in the standard media and the other tested yeasts mainly showed lipo-tolerance but not lipoaffinity for these compounds. To our knowledge, this is the first report on the influence of pulmonary lipids in the in vitro development of Malassezia spp and other yeasts members of the lung mycobiome.