## 2 Results and Discussion
### VOCs Profile Differentiation in Four Growth Media in the Exponential and Stationary Phase  
Unpublished data by [PERSON] et al. (2017) showed that _M. furfurr_ CBS 1878 is capable of growing in modified Dixon (mDixon) and OA media, whereas it can only survive in OA+PA and PA media (Figure S1), as can be verified by the absence of growth (exponential phase) in these last two media [21]. When the growth medium is supplemented with a mixture of PA and OA, the toxic effect of PA is, at least partly, relieved and _M. furfur_ is able to grow (Figure S1). In this research, using a univariate (UVA) and a multivariate (MVA) statistical analysis, we proved that the growth media and phases produced differences in the volatile profiles released by _M. furfur_. We demonstrated that, for 17 VOCs, peak areas significantly change when the medium-growth phase is modified (ANOVA, \(2.37<\) F \(<\) 560.26, _P_\(<\) 0.05) (Kruskal-Wallis test, \(14.34<\) K \(<\) 34.60, _P_\(<\) 0.05) (Table S1). We reported VOCs with _P_\(<\) 0.05 in a parametric and a non-parametric test, because more than half of the compounds (34 of 61) did not have a normal distribution (Shapiro-Wilk test, \(0.59<\) W \(<\) 0.91, _P_\(<\) 0.05). Figure 2 summarizes the semi-quantitative differences in the total peak areas between each treatment for these 17 VOCs. The peak areas of carbon dioxide released by _M. furfur_ growing in mDixon were higher than in the other treatments, evidencing an increased respiration in this medium due to an increase in growth (Figure S1). Octane and nonane were released in the mDixon and OA+PA media with semi-quantitative differences in their areas. Hexan-1-ol, butan-1-ol, and the Isomer3 of methyldodecane were released in all media, except in PA. In contrast, the rest of the VOCs were released by _M. furfur_ almost exclusively in the mDixon or in the OA+PA media (Figure 2). Differences among exponential and stationary phases were also observed, being some compounds increased in the stationary phase, such as dimethyl sulphide, and others decreased, such as octane. The presence of dimethyl sulphide, and other volatile organic sulphur compounds (VOSC), has been previously reported in bacteria [49], ascomycota yeasts [50; 51], and basidiomycota yeast [52]; however, to the best of our knowledge, this is the first report of this compound in the genus _Malassezia_. Another commensal microfungi, _Candidia albicans_, shared the presence of dimethyl sulphide, 2-methylpropan-1-ol, pentan-2-one, and 3-methylbutan-1-ol with _M. furfurr_[53]; however, the ecological functions of these VOCs for both remain unknown. The presence/absence of some specific VOCs in _M. furfur_ highlights the importance of analyzing the different volatiles profiles of a single species in different environments, especially when the objective of the research is to track biomarker compounds for chemotaxonomic, biotechnological [31], or therapeutic purposes [46]. Chemical differentiation in the VOCs released should be studied whenever possible. Previous reports using UVA showed that the emission of some VOCs in other fungi, such as _Ceratocysts sp._, _Lentinus lepideus_, _Aspergillus versicolor_, _Aspergillus fumigatus_, _Penicillium commune_, _Cidosporium cladosporoides_, _Pacetilomyces variotiii_, _Philophora fastigiata Trichoderma spp._, and _Kluyveromyces marzianus_, depends highly on the differences in the nutritional supplement of the growth medium [25; 42; 43; 54; 55; 56]. Using Hierarchical Cluster Analysis (HCA), we discovered that the five replicates from _M. furfurfur_ growing in the mDixon and OA+PA in the exponential and stationary phase have a signature profile that is easily differentiated from the profiles of other treatments; however, the grouping is not related to a specific chemical class of compounds (Figure 3). This aggrupuation validates the reproducibility of the volatiles profiles, although some VOCs showed an evident high variance of transformed and scaled peak areas in the heatmap.