## 3 Results and Discussion
### Composition of Thermodynamic LAB Populations  
One hundred and eighty-two colonies of LAB (gram-positive and catalase-negative) were isolated from all samples collected during cheese production, from pasteurized ewe's milk before MSC addition to processed cheeses. All isolates were subjected to RAPD  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Microbial Counts**} & \multicolumn{3}{c}{**Samples**} & \multirow{2}{*}{**SEM**} & \multirow{2}{*}{**\(p\)-Value**} \\ \cline{2-2} \cline{5-5}  & **RM** & & & **PM** \\ \hline TMM & 6.02  & 3.24  & 0.45 & \textless{0.0001} \\ Cockus LAB & 5.71  & 2.91  & 0.44 & \textless{0.0001} \\ End  
analysis, a technique commonly used for strain typing and to monitor the starter LAB deliberately added [65]. The dendrogram reported in Figure 5 shows only 29 strains; this is because the rest of the isolates were characterized by polymorphic profiles already included in the dendrogram.  
Figure 4: Growth of starter cultures during Tuma cheese productions. (**a**) total mesophilic microorganisms; (**b**) _Lactococcus lactis_. Units are Log CFU/mL for milk and whey samples and Log CFU/g for curd and cheese samples. Abbreviations: CCP, control cheese product inoculated with the milk starter cultures (MSC); ECPO100, experimental cheese product inoculated with MSC + 100 \(\upmu\)L/L of oregano essential oils (OEOs); ECPO200, experimental cheese product inoculated with MSC + 200 \(\upmu\)L/L of OEOs.  
Figure 5: Dendrogram obtained from combined RAPD-PCR patterns of LAB strains isolated from pasteurized ewe’s milk to Tuma cheeses. Abbreviations: CCP, control cheese product inoculated with the milk starter cultures (MSC); ECPO100, experimental cheese product inoculated with MSC + 100 \(\upmu\)L/L of oregano essential oils (OEOs); ECPO200, experimental cheese product inoculated with MSC + 200 \(\upmu\)L/L of OEOs; PM, pasteurized milk; IM, inoculated milk; W, whey; C, curd; Ch, cheese; _L.c., Lactococcus; Str., Streptococcus_.  
Two major RAPD clusters were identified. Each cluster included one of the _Lc. lactis_ strains used for MSC preparation. In particular, _Lc. lactis_ (NT1 and NT5) was detected in all samples collected from the control and experimental products. Three different strains isolated from pasteurized ewe's milk were identified as _Lc. lactis_ subsp. _lactis_ (Ac. No. OQ675106) and _Str. thermophilus_ (Ac. No. OQ675104-OQ675105). These species are part of the typical starter LAB cultures, which are able to generate a high amount of lactic acid during the very first steps of cheese production through the fermentation of lactose [66]. Although they are commonly part of raw milk microbiota [67], their ability to survive the pasteurization process is well known [68; 69]. However, raw milk LAB strains were not found at dominant levels in any of the samples analysed after the addition of MSC, evidencing the ability of the starter cultures to dominate over the indigenous milk LAB that survived to the pasteurization treatment. These results confirmed those obtained by microbial counts that excluded any negative influence of OEO during the fermentation process.