## 2 Results
### The Volatile Profile Allows the Separation of Malassezia Species and Growth Phases
The first PCA dimension explained 23% of the total variance, which allowed for the separation of _M. sympodialis_ in the exponential and stationary phases. Likewise, in this component, the differentiation of _M. globosa_ and _M. restricta_ in the exponential phase is evident (Figure 4). The other two dimensions of PCA explained 12% and 10% of the total variance, where it is possible to differentiate _M. globosa_ and _M. restricta_ in the stationary phase. PCA allowed for the partial discrimination and separation of the _Malassezia_ species according to their volatile profile. In addition, chemical differentiation in the VOCs caused by the growth phase was observed. It was possible to note a high similarity between the three species in the stationary growth phase despite the high variation observed among replicates, especially for _M. restricta_ in the stationary phase with a larger ellipse (Figure 4). Second, supervised multivariate analyses were performed to confirm the chemical differentiation of the _Malassezia_ species. Notably, 2D-projection to latent structures-discriminant analysis (PLS-DA) showed the discrimination of species, growth phase, and  
Figure 2: Venn diagram of the volatile profile of _Malassezia_ spp. The diagram indicates unique and shared compounds between _Malassezia_ species. Fifty-four volatile organic compounds were identified for all species. species/growth phase according to their VOC profiles. Figure 5a shows differences among species (R2X = 0.514, R2Y = 0.927, Q2 = 0.798), Figure 5b shows differences among growth phases (R2X = 0.319, R2Y = 0.954, Q2 = 0.877), and Figure 5c shows differences among species/growth phases (R2X = 0.58, R2Y = 0.896, Q2 = 0.727). In all cases, the Q2 metrics provided evidence of appropriate adjustment of the model. In Figure 5a, discrimination in component 1 explains 19% of the variance and distinguishes _M. globosa_ from the other two species; likewise, component 2 explains 11% of the variance and separates the volatile profile of _M. restricta_ from those of the other two species. In Figure 5b, both phases were perfectly separated in two dimensions, explaining 22% and 10% of the total variance. In addition, the R2Y (0.954) and Q2 (0.877) values indicate that the model is valid, and the prediction accurately explains the importance of the growth phase in the volatile profile. Figure 5c confirms that species and growth phases can differentiate VOCs. The first component summarizes 23% of the variance, while the second explains 11%. In this plot, the first component showed that _M. restricta_ and _M. sympodialis_ were partially separated. In the second component, _M. globosa_ in the exponential and stationary phases was discriminated from the other species. Figure 3: Gas chromatographic profiles of volatile organic compounds (VOCs) detected in the headspace of _Malassezia_ spp. in the exponential and stationary growth phases. The gray line corresponds to the volatile profile of the control, which is mDixon media without yeasts. To estimate which volatile compounds contribute to the differentiation pattern in the PLS-DA made by species/growth phase, variable importance in projection (VIP) scores was calculated. VIP scores indicate the importance of each variable in the projection used in a PLS-DA model. Factors with VIP scores greater than one are regarded as significant [35]. The VIP showed the 24 most important VOCs that better differentiate between species/growth phases (Figure 5d). The unknown seven compounds had higher scores and were released by _M. sympodialis_ in the stationary phase. Unique compounds produced by a unique species, or even compounds produced in a specific growth phase (Table 2), usually presented higher VIP scores. For instance, non-3-en-1-ol (VIP approximately 1.6) was detected only in the stationary phase for all species, and (3E)-octa-1,3-diene (VIP approximately 1.2) was emitted only by _M. sympodialis_ in both development phases (Table 2, Figure 5d). Likewise, octan-3-one (VIP approximately 1.3) is released only by _M.