## 3 Results and Discussion
### Determination of the Microbiota of Edam Cheeses by High-Throughput Sequencing (HTS)  
The number of 16S rRNA sequence reads ranged from 332,280 to 436,468 in cheese samples after 52 days of ripening. The predominant microbial groups belonged to four phyla: Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes (Figure 1). Eleven predominant genera were identified in the group of 32 genera and taxonomic groups that accounted for at least 0.5% of the bacterial community. They were: _Acetobacter_, _Alcaliphilus_, _Bacillus_, _Bideroides_, _Bifidobacterium_, _Cellulomonas_, _Clostridium_, _Lactococcus_, _Lactobacillus_, _Leucobacter_, _Propionibacterium_, and one group of \(\gamma\)-Proteobacteria. Similar results were reported in a study of Oscypek, a traditional Polish smoked cheese made of sheep's milk [37]. The authors demonstrated the predominance of the same four phyla and identified nine identical genera and taxonomic groups in 40 operational taxonomic units (OTUs). The proportions of the remaining genera were below 0.5%, and not all genera were identified in all samples. The average bacterial identification levels were similar (75-70%) in the spring and autumn seasons. In autumn and spring samples, 25% and 30% of the sequences could not be identified, respectively. The genera represented by dozens or hundreds of reads, including Archaea and algae (Eukaryota), accounted for a large part of the taxonomic spectrum in cheese samples. A high number of DNA sequences were not classified in the remaining cheese samples (Figure 1). The above could be attributed to the presence of microorganisms that have not yet been classified or microorganisms containing degraded DNA. [PERSON] et al. [38] observed that DNA was degraded to very short fragments during corn dough fermentation. The content of bacterial proteases, proteinases, and peptidases increases gradually during cheese ripening and storage. Similarly to bacterial proteases, DNA-degrading enzymes (nucleases) can also be released into the cheese matrix during the autolysis of starter and non-starter lactic acid bacteria [39], or they can be bacteriophage-derived [19]. The highest number of reads was obtained for two out of the three genera of starter bacteria: _Lactococcus_ and _Propionibacterium_. In the analyzed group of the SLAB, _Lactococcus_ was the predominant  
Figure 1: The average relative abundance (%) of the sequences identified at phylum level in samples of Edam cheese. genus in the phylum Firmicutes, and it accounted for 43.78% and 53.35% of the microbial communities in autumn and spring cheese samples, respectively. The second most dominant starter culture belonged to the genus _Propionibacterium_, phylum Actinobacteria. _Propionibacterium_ counts were lower, and they were determined at 9.41% and 12.37% in spring and autumn cheese samples, respectively. A comparison of the number of reads for the selected bacterial genera revealed important differences, including in starter bacteria that are added in strictly controlled amounts to every cheese batch. The number of reads for the third genus of starter bacteria, _Leuconostoc_, was very low at a fraction of a percent (Figure 2 and Table S1). The analyzed cheeses were characterized by highly diverse microbiota. Starter bacteria develop in the first stages of the production process and dominate over residual microflora and the microorganisms from secondary infections. During ripening, bacterial starter cells are gradually autolyzed, which promotes the growth of non-starter bacteria that can also influence the attributes of the final product [40]. For this reason, the microbiota of ripened cheese are more diverse than those observed immediately after production or short ripening. [PERSON] et al. [41] demonstrated that the microbiota of Grana-like cheese begin to diversify upon brining and undergo significant changes during two months of ripening. In the present study, starter bacteria were predominant in the Edam cheese.