## 3 Results
### Effect of Lactobacillus spp. Isolated from Yoglurt on Selected Potentially Pathogenic Bacteria
_monocytogenes_ (Figure 3). Among pathogenic bacteria, the highest number of bacteria after 72 h incubation with \(L\). _paracasei_ was shown for \(E\). _coli_ (4.64 log CFU \(\times\) cm\({}^{-3}\)) and the lowest (4.37 log CFU \(\times\) cm\({}^{-3}\)) for \(S\). Enteritidis (Figure 3). Figure 2: Changes in the number of \(L\). _rhamnosus_ and foodborne bacteria after 72 h of incubation in individual cultures (LRA—\(L\). _rhamnosus_; ECO—\(E\). _coli_; LMO—\(L\). _monocytogenes_; SAL—S. Enteritidis) and in mixed cultures (LRA+ECO—changes in the number of \(L\). _rhamnosus_ in a mixed culture of \(L\). _rhamnosus_ and \(E\). _coli_; ECO+LRA—changes in the number of \(E\). _coli_ in a mixed culture of \(L\). _rhamnosus_ and \(E\). _coli_; LRA+LMO—changes in the number of \(L\). _rhamnosus_ in a mixed culture of \(L\). _rhamnosus_ and \(L\). _monocytogenes_; LMO+LRA—changes in the number of \(L\). _rhamnosus_ in a mixed culture of \(L\). _rhamnosus_ and \(L\). _monocytogenes_; LRA+SAL—changes in the number of \(L\). _rhamnosus_ in a mixed culture of \(L\). _rhamnosus_ and \(S\). Enteritidis; SAL+LRA—changes in the number of \(S\). Enteritidis in a mixed culture of \(L\). _rhamnosus_ and \(S\). Enteritidis). a–  
The above trend is confirmed by the calculated changes in the number of tested bacteria after 72 h of incubation (Figure 4). In monocultures, an increase in the number of all tested bacteria was observed. For _L. paracasei_, the calculated increase was statistically significantly different (\(p\leq 0.05\)) compared to the _L. monocytogenes_ (Figure 4). In the mixed culture with all the tested pathogenic bacteria, the number of _L. paracasei_ (LPA+ECO, LPA+LMO, LPA+SAL) increased, but the results were not statistically significant (\(p>0.05\)). In the case of all pathogenic bacteria with _L. paracasei_, their numbers decreased (Figure 4). These decreases ranged from \(-2.64\) log CFU \(\times\) cm\({}^{-3}\) for _E. coli_ (ECO+LPA) to \(-3.22\) log CFU \(\times\) cm\({}^{-3}\) for \(S\). Enteritidis (SAL+LPA) (Figure 4). No statistically significant differences were found between decreases in the number of pathogenic bacteria after culturing with _L. paracasei_ (\(p>0.05\)). In the mixed cultures (_L. rhamnus_ and _L. paracasei_), an increase in _Lactobacillus_ spp. was observed, while pathogenic microorganisms decreased. After 72 h of incubation, the highest increase (\(8.64\) log CFU \(\times\) cm\({}^{-3}\)) in _L. rhamnus_ and _L. paracasei_ was observed for the mixed culture with \(S\). Enteritidis, and the lowest (\(8.39\) log CFU \(\times\) cm\({}^{-3}\)) in the presence of _E. coli_ (Figure 5). Among pathogenic bacteria, the highest number of bacteria after 72 h incubation with the _Lactobacillus_ spp. MIX was shown for _E. coli_ (\(4.50\) log CFU \(\times\) cm\({}^{-3}\)) and the lowest (\(4.04\) log CFU \(\times\) cm\({}^{-3}\)) for S. Enteritidis (Figure 5). Figure 3: Changes in the number of bacteria in relation to culture time. (**A**) Positive control. (**B**) Changes in the number of bacteria in a culture of _L. paracasei_ with _E. coli_. (**C**) Changes in the number of bacteria in a culture of _L. paracasei_ with _L. monocytogenes_. (**D**) Changes in the number of bacteria in cultures of _L. paracasei_ and \(S\). Enteritidis. LPA—_L. paracasei_; ECO—_E. coli_; LMO—_L. monocytogenes_; SAL—_S_. Enteritidis; CFU—colony-forming unit. Figure 4: Changes in the number of _L. paracasei_ and foodborne bacteria after 72 h of incubation in individual cultures (LPA—_L. paracasei_; ECO—_E. coli_; LMO—_L. monocytogenes_; SAL—_S. Enteritidis) and in mixed cultures (LPA+ECO—changes in the number of _L. paracasei_ in a mixed culture of _L. paracasei_ and _E. coli_; ECO+LPA—changes in the number of _E.coli_ in a mixed culture of _L. paracasei_ and _E. coli_; LPA+LMO—changes in the number of _L. paracasei_ in a mixed culture of _L. paracasei_ and _L. monocytogenes_; LMO+LPA—changes in the number of _L. monocytogenes_ in a mixed culture of _L. paracasei_ and _L. monocytogenes_; LPA+SAL—changes in the number of _L.