Yeast Smell Like What They Eat: Analysis of Volatile Organic Compounds of _Malassezia furfur_ in Growth Media Supplemented with Different Lipids  
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1 Laboratory of Advanced Analytical Techniques in Natural Products (LATNAP), Universidad de los Andes, Cra 1 No. 18A-12, Bogota 111711, Cundinamarca, Colombia; [EMAIL_ADDRESS]  
[PERSON]  
fungal microbiota, accumulating at different body sites, especially behind the ears [5] and on the scalp [6]. These organisms have been recognized as aetiological agents of pityriasis versicolor and might also be related to other skin diseases, such as seborrheic dermatitis, dandruff, folliculitis, atopic/eczema dermatitis syndrome, and psoriasis [7]. Depending on the stimulation, or occasionally the downregulation of the immune response against _Malassezia_, these yeasts could remain as a commensal or eventually become pathogenic [8]. The causes related to this interconversion are still unknown. There are different studies suggesting that a relationship exists between pathogenicity and modifications in the lipid compositions of the host [9; 10] or changes in the skin microbiota [11; 12]. The complexity of the human skin environment hinders the possibility of fully comprehending the host-microbe and microbe-microbe interactions [13], because the skin determines the microbiota and, at the same time, the resident microbial communities modify this environment in a dynamic process [14]. Host demographics and genetics, human behavior, local and regional environmental characteristics, and transmission events determine the human skin microbiota variability [15]. The spatial distribution of the micro-organisms is also highly variable [5]. _Malassezia_ and _Ctibacterium acnes_ (formerly _Propionibacterium acnes_) [16] reside in areas with a high density of sebaceous glands, whereas _Staphylococcus_ and _Corynebacterium_ are mostly prevalent in areas with a high temperature and humidity [17]. Any changes in these conditions may affect homeostasis and promote a pathogen or even a commensal, such as _Malassezia_, to cause disease. Some _Malassezia_ species can easily be differentiated by the types of lipids necessary to grow them in certain media [18; 19]. Therefore, the _Malassezia_ assimilation assay is widely used to determine the lipidic requirement of different strains [3]. For example, palmitic acid (PA) has a fungicidal activity in _Malassezia pachy dermatitis_, in an atypical strain of _Malassezia furfur_, and in _Malassezia sympodialis_, but not in _M. furfur_ CBS 1878 [20]. The addition of oleic acid (OA) produces a fungistatic effect on _M. pachy dermatitis_, on atypical _M. furfur_, and on _M. furfur_ CBS 1878, but on _M. sympodialis_ OA produces a fungicidal effect [21]. Therefore, Dixon, mDixon, and Leeming and Notham (LNA) media are the most widely used for culturing _Malassezia_, because their more complex composition and the presence of Ox bile (obtained after purifying and drying fresh bile from oxen) offer the essential nutritional requirements for their growth [8; 22]. The ability of _M. furfur_ to survive in PA could not be related to the presence of a \(\Delta\)9-desaturase gene OLE1, which is involved in the conversion of saturated to unsaturated acids, such as PA to palmitoleic acid, because this gene has also been found in other species/strains where PA is fungicidal [3; 21]. Thus, the lipid-dependent and lipophilic lifestyle of _Malassezia_ spp. could determine its ecological niche in the skin environment of human and animal hosts [20]. Understanding new aspects of the lipid metabolism of these yeasts is expected to provide new insights into their biology and ecology, and, therefore, illuminate the path to understanding interconversions between commensalism and pathogenicity [21]. As they can be easily collected, fungal volatile organic compounds (VOCs) are one of the means to assess the metabolic profiles of fungi related to certain diseases [23; 24; 25; 26; 27; 28; 29].