## 3 Results  
### Abundance and Diversity of Microorganisms in Red Wines  
Samples of the red wines were clustered on the basis of sequences of a fragment of 16S rDNA (bacteria) and region ITS1 rDNA (fungi). The red wines differed in the number of raw reads, the number of Operational Taxonomic Units (OTUs), and microbial diversity (Table 1). The largest number of bacterial OTUs was found in DB wine, followed by WJ wine; MD wine contained a small quantity of bacterial OTUs, but was the most abundant in fungal OTUs, followed by DB and then WJ. However, the number of OTUs was not an indicator of the microbial diversity of the investigated wines, as the largest numbers of bacterial species were found in MD wine, while fungal diversity was the highest in DB wine and the lowest in WJ wine. Chao 1 indexes and the numbers of species for each wine were also much higher for bacteria than for fungi, and they were similar for MD and DB, 44/29 and 43/30, respectively. [PERSON]'s and [PERSON]'s diversity indexes reflect the uniformity of distribution of microorganisms. The former is a measure of population evenness indicating the probability of two randomly sampled individuals belonging to two different taxa. The latter combines both evenness and richness, but it quantifies the uncertainty in the taxon identity of a randomly chosen individual [19]. High values of these indexes are suggestive of a better uniformity of distribution, which means that MD was the best one in this respect. On the other hand, WJ and DB wines showed the lowest values of the mentioned indexes for fungi and bacteria, respectively. Table 2 shows relative abundance of the genera of bacteria and yeast identified by metagenetic analysis of the Polish red wines. A total of 19 bacterial genera and 15 yeast genera were detected. The numbers of bacterial genera for each wine were as follows: 13 for DB, 14 for MD, and 12 for WJ, but the numbers of genera with RA above 10% were 2, 3, and 2, respectively. _Lactobacillus_ (before changes in taxonomy of LAB) was present in all wines at 14.98% to 28.53%. The bacterium _Tatumella_ was also found in all wines, but it was observed in large amounts in DB and WJ wines only. _Lactococcus_ and _Gluconcobacter_ were present in each wine, but their RA was below 10%. As shown in Figure 1 and Table S1, the three wines differed significantly in bacterial species composition. _Tatumella ptyseos_ was the main species in DB and WJ wines (74 and 63%, respectively), _Lactiplantiobacillus plantarum_ (formerly _Lactobacillus plantarum_) was the most highly represented in DB and MD wines (14.6 and 21.8%, respectively), and _Apliacobacillus kunkei_ (formerly _L. kunkei_) was the most abundant in WJ wine (17.7%). On the other hand, _Lactoulos pactoulosenteroides_ (29.6%) and _Komagaitobacteras sacchirotrans_ (18.3%) were found only in MD wine. Among yeasts (Table 2 and Table S2), the genus _Saccharomyces_ (RA between 47 and 90%) was the most abundant taxon, which is normal for wines after fermentation, but there were large differences in RA values between the wine samples. This genus was represented by the species _S. cerevisiae_ (in DB and WJ), 76.6 and 89.7%, respectively) and _S. caricacanus_ (in MD, 40%). On the other hand, wines DB and MD, contained fairly abundant groups of _Saccharomyces_ which could not be identified, probably due to missing reference sequences in databases. The genus _Hansenuspora_, represented by the species _H. uarum_, was identified in all the wines at 4.4-8.5%. Another yeast characteristic of the fermentation environment, _Toruspora delbrueckii_, was present only in WJ wine (above 1%). Each wine also contained other fungi: _Aureokasidium pullulans_, _Alternaria infectoria_, _A. rose_, _A. tenuissima_, and _Mycosphaerella tasiana_. Figure 1B shows bar plots of RA of the main yeast species for the three wines studied.