# Influence of Terroir on Microbial Diversity and Wine [PERSON]
## 3 Results and Discussion  
### Microbiological Analysis  
A total of 292 isolates were obtained during the spontaneous fermentation of the must, as mentioned in the section, \"Isolation of Autochthonous Wine Yeasts\" in Materials and Methods. Total isolates from the QZ zone were used to differentiate the percentage of _Saccharomyces_ and Non-_Saccharomyces_ yeasts between the various wineries. It was shown that there was a greater number of isolates that corresponded to the Non-_Saccharomyces_ genus. However, in Figure 1c, which corresponds to the PZ zone, it is observed that the highest percentage of the isolates obtained belong to the _Saccharomyces_ genus. The results obtained in Figure 1a show that in QZ there is a greater number of yeast isolates during spontaneous fermentation of the must compared to PZ. This may be due to the absence of the qualitative killer activity of the yeasts since, as shown in Figure 2a, most of the yeasts found do not present killer activity, leading to the absence of biological control. In PZ it was found that there is greater killer activity of the yeasts, which could modify the population patterns of the fermentation and its evolution [23], obtaining a lower number of cultivable yeast isolates. Killer activity is carried out by yeasts that produce substances known as \"killer substances\". These substances are antimicrobial protein compounds that inhibit the growth and development of yeast strains susceptible to these toxins, but not their own producers [24]. These proteins have a heterogeneous structure in size and complexity. This explains the lower number of cultivable isolates in the ZP zone, since by having a higher killer activity it can be concluded that in this zone there is a greater number of yeasts sensitive to these toxins. Figure 1b illustrates the distribution of yeast isolates from the QZ zone, highlighting the proportions of _Saccharomyces_ and Non-_Saccharomyces_ yeasts in the various wineries. The data reveal a predominance of Non-_Saccharomyces_ isolates in this zone. In contrast, Figure 1c, which represents the PZ zone, shows a markedly different pattern. In this zone, the majority of isolates belong to the _Saccharomyces_ genus, indicating a significant change in the dynamics of the yeast population between the two zones. Figure 2b shows the qualitative activity of the \(\beta\)-glucosidase enzyme observed in the different isolates in various musts. It is noteworthy that PZ yeasts exhibit higher activity levels compared to QZ yeasts. \(\beta\)-glucosidase is a significant and well-studied enzyme due to its main role in the hydrolysis of substrates with glycosidic bonds, thus releasing glucose and aglycones [25]. This enzyme is responsible for the cleavage of glycosidic bonds such as 1,4-\(\beta\) and 1,6-\(\alpha\) bonds, promoting the formation of free terp  
Figure 2: **(a)** Percentage of killer activity in the quality zone and production zone. **(b)** Percentage of \(\beta\)-glucosidase activity in the quality zone and production zone. **(c)** Percentage of cellulose activity in the quality zone and production zone. **(d)** Identification of Non-_Saccharomyces_ yeasts in the quality zone and production zone. and aliphatic esters. In fruit-based juices and wines, numerous aroma precursors exist in the form of glycosides. In grape-derived wines, the predominant aromatic glycosides are terpen [26]. Under the catalytic action of \(\beta\)-glucosidase, these glycosides release volatile aromatic compounds, improving the sensory properties of the wine [27]. The aromatic compounds that are related to this activity are geraniol, nerol, citronello1, linalool, and \(\alpha\)-terpineol [28]. Consequently, it can be concluded that PZ yeasts have a high potential to improve the aromas associated with compounds derived from glycosides; this explains, for example, that the concentration of citronello1 in the production zone is higher compared to the quality zone.