## 3 Results and Discussion
### Microbial Identification  
Fermentation is an old technique used by different civilizations for the elaboration and the preservation of foods. Records of different fermentation methods applied to a variety of raw materials demonstrate that this practice has been applied since 6000 BC in the Middle East region [29]. This metabolic process is critical in food elaboration, affecting the organoleptic quality of the raw material [30]. During the production of many autochthonous alcoholic beverages, the participation of microbial consortiums converts the fermentable sugars present in the media into ethanol and secondary metabolites of important flavor attributes [31]. Thus, different species of filamentous fungi and yeasts can participate in spontaneous fermentations. In Figure 2, we present the fungal diversity and the genus of microorganisms identified in the samples of fermented sold must, and data showing the application of some of the species recognized in this study can be found in the Supplementary Materials (Table S1). In Figure S2 of this section, we present photos of DNA extraction from samples of spontaneous fermented sold must, and in Figure S3 we present the amplification of DNA by PCR, from sold samples. It was observed that Ascomycata is the phylum of most microorganisms identified with 1449 strains, followed by Basidiomycota with 26 strains, Glomeromycota with nine strains, and 448 strains of not identified fungi (Figure 2). The genus of the identified strains was conformed mostly by _Galactomyces_ (192), _Bionectria_ (187), _Dipodascus_ (118), _Fusarium_ (112), _Pichia_ (101), and _Apergillus_ (84), and of _Saccharomyces_, only 13 strains were recognized (Figure 2). In previous works, species of _Galactomyces_ were identified as the dominant yeasts [32], and particularly the species _Galactomyces geotrichum_, identified in fermented sold must (see Table S1), has been attributed to possess the metabolic pathways to produce significant aromatic metabolites [33]. _Dipodascus_, a group of yeasts described as extremophiles, were reported in the fermentation of coffee beans performed in open tanks and are vulnerable to contamination from air, human contact, and insects [34]. Additionally, species of _Dipodascus_ have been identified in the tissue of cactusindigenous to the Americas, specifically in Southern Arizona [35], a region that shares geographic and environmental conditions with the Chihuahua desert, which is the native habitat of sotol (_Dasyliron_ spp). Another group of yeasts identified in fermented sotol must was _Pichia_ sp., which has the metabolic ability to consume sotol must sugars and is capable of adapting to the stress factors of sotol processing. In a previous work about the production of potential volatile flavor metabolites isolated from the spontaneous fermentation of coffee beans pulp, strains belonging to the species _Pichia kudriazvevii_ were the most aroma-producing yeasts [36]. This Pichia species was identified during sotol must fermentation (see Table S1). Furthermore, these yeast species have been reported in several spontaneous fermentation processes, such as in Ghanaian and Ivorian cocoa beans fermentation, where the dominance of _Pichia kudriazvevii_ strains is attributed to their ability of adaptation to stressful environmental conditions, such as elevated ethanol concentrations, high temperatures, and low acidity levels [36]. Moreover, these species can be found in foods containing high levels of sugars, such as maple syrup, fruit juices, dry fruit, jams, honey, and fermented honey [37]. Furthermore, _Pichia_ species (main non-_Saccharomyces_ yeasts) have been identified during the fermentation of alcoholic beverages [38; 39] and in distilled spirits. They contribute to the aroma of these by the production of metabolites such as esters, higher alcohols, acids, terpenoids, and aldehydes [40]. Therefore, this yeast genus encompasses the biosynthetic ability to play a significant role during the spontaneous fermentation of sotol must.