## 3 Results and Discussion  
### Bacterial Population Profile in Sheep's Cheese  
The NGS sequencing of the 16S rRNA gene allowed the characterization of the bacterial microbiota of 13 sheep's cheese samples. For this, 1,061,392 bacterial sequences were obtained, emphasizing samples QJ188 and VF712, which presented 155,791 and 145,942 sequences, respectively. Of the total sequences, 3732 were not identified and/or classified as bacteria. From reading the sequences, five phyla were identified: Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes, and Fusobacteria, with the first two being the most abundant, with 95.7% and 3.4%, respectively (Figure 1). The analysis carried out in VITCOMIC confirmed this result, which showed high similarity (>90%) of the majority of sequences with the two phyla mentioned above (Figure 2). Considering the phylum Proteobacteria, the most abundant class was Gammaproteobacteria (Figures 1B and 2A). Other studies with sheep's cheese report the predominance of the phyla Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria, highlighting the phylum Proteobacteria as it includes families of potential human pathogens, such as _Enterobacteriaceae_ and _Moraxelaceae_[44; 74; 75; 76]. The relative abundance of phyla is directly influenced by factors such as care with raw materials, materials, and utensils until obtaining the final product [77], as well as by the severe thermal processing of milk, which ends up inhibiting part of the microbial population and, consequently, diversity decreases [77]. Therefore, to make up for the absence of autonomous fermenting bacteria, which are responsible for guaranteeing the organoleptic characteristics of the cheese, cultures containing LABs were used, which were the basis of the microbiota of the dairy product [78]. Figure 1: Relative abundance of bacterial taxa identified in sheep’s cheese samples, sold in the southern region of Brazil, with more than 1% abundance. (**A**) Phyla; (**B**) Class; (**C**) Order; (**D**) Family; (**E**) Genus; and (**F**) Species. Figure 2: Abundance and similarity of bacterial groups of sheep’s cheese 16S rRNA genes using the VITCOMIC circular diagram. (**A**) Phylum-level similarity of the general population of bacteria; (**B**) phylum-level similarity of the BPP/BHMT population. The color of each group varies according to the legend in the left corner of the figure, ranging from more presence (reddish) to less presence (bluish/purple). The circles filled in orange represent the abundance according to the percentage of similarity with the sequences in the database. The symbol # is related to number of reads in each of the orange dots in the image. From the taxonomic classification, it was possible to identify 45 genera and 57 bacterial species in the 13 sheep's cheese samples. Of these, we can observe the predominance of LABs, especially the genus _Streptococcus_, which represents around 60% of the total abundance, followed by _Lactococcus_, _Lactobacillus_, and _Lacticaseobacillus_, which account for 34.7%. The genera _Pseudomonas_ and _Acinetobacter_ represent 2.0% and 1.4% of the total sequences, respectively. Considering these last two genera, sample VF712 stands out with 17.8% of _Acinetobacter_ abundance and PT570 with 25.6% of _Pseudomonas_. The remaining genera had abundances below 1% each. The phylogenetic relationship of the bacterial sequences identified in sheep's cheese sold in southern Brazil can be understood in Figure 3. Initially, the tree was divided into two branches: the first branch with a clade (dark green--right and central region) consisting of species from the genera _Acinetobacter_, _Moraxella_, and _Psychrobacter_, and the second branch with other genera/species. This result highlights the evolutionary distance of the species present in the dark green clade in relation to the rest of the cheese population.