## 2 Materials and Methods
### Antimicrobial Activity Assay
Figure 5: Chromatographic profile of _Lactiplantiobacillus plantarum_ ATCC14917 showing antimicrobial activity. High mass accuracy spectrum of compound (B) OH-PLA (16.3 min); high mass accuracy spectrum of compound (J) Vanillic acid (21.3 min); high mass accuracy spectrum of compound (O) 4-Hydrocinamic acid (27.4 min); high mass accuracy spectrum of compound (L) Ferulic acid (28.7 min); high mass accuracy spectrum of compound (M) Benzoic acid (34.2 min); high mass accuracy spectrum of compound (G) Salicylic acid (36 min). The present study investigated the antimicrobial activity of the obtained CFSs after 30 days incubation of the three LAB strains against pathogenic microbial species (_Salmonella enterica_ ATCC14028; _Staphylococcus aureus_ ATCC 29213; _Escherichia coli_ ATCC 25922; _Klebsisella pneumoniae_ ATCC 700603). The inhibition of active antimicrobial substances produced by different LAB species after incubation at 37 \({}^{\circ}\)C and against pathogens appeared to be similar, as shown in Table 4 and in Figures 6-9. All obtained CFSs from LAB cultures showed significant inhibitory effects on the tested Gram-negative and -positive pathogens. The isolated LAB inhibited the growth of the tested pathogenic strains successfully, indicating that the addition of LAB strains in commercial food products may provide effective protection against infections caused by specific pathogens. All the metabolites produced from the three LAB species that were incubated for 5 days at 37 \({}^{\circ}\)C inhibited all the pathogen microorganisms. The potential application of LAB for the control of the proliferation of undesirable microorganisms has been reported for different food products of plant or animal origin [29; 30; 31]. In future studies, it would be desirable to conduct targeted assays for antifungal molecule identification and quantification by combining different extraction and analysis methods, such as LC-MS/MS or GC-MS. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \multirow{2}{*}{**Name Strain**} & \multirow{2}{*}{**Cfu/mL**} & **Incubation** & **DL-p-Hydroxy-Phenyllactic Acid** & **Salicylic Acid** & **Vanillic Acid** & **Ferulic Acid** & **Benzoic Acid** & **4-Hydro-Cinnamic Acid** \\ \hline \multirow{6}{*}{_Levilactobacillus brevis_ (ppm)} & \(10^{8}\) & 5 & 80.2 & - & 1.5 & - & - & - \\ \cline{2-8}  & \(10^{5}\) & 10 & 98.3 & - & 2.4 & - & - & - \\ \cline{2-8}  & \(10^{5}\) & 15 & 100.2 & - & 2.4 & - & - & - \\ \cline{2-8}  & \(10^{4}\) & 20 & 102.3 & - & 2.5 & - & - & - \\ \cline{2-8}  & \(10^{4}\) & 25 & 103.4 & - & 2.6 & - & - & - \\ \cline{2-8}  & \(10^{2}\) & 30 & 103.4 & - & 2.6 & - & - & - \\ \hline \multirow{6}{*}{_Lacitplantiobacillus plantarum_ (ppm)} & \(10^{8}\) & 5 & 150.3 & 1.0 & 2.2 & 4.8 & 3.2 & 1.0 \\ \cline{2-8}  & \(10^{5}\) & 10 & 200.10 & 1.6 & 3.2 & 6.05 & 3.8 & 1.25 \\ \cline{2-8}  & \(10^{5}\) & 15 & 214.3 & 1.6 & 3.3 & 6.35 & 3.9 & 1.3 \\ \cline{2-8}  & \(10^{3}\) & 20 & 216.8 & 1.72 & 3.35 & 6.40 & 4.4 & 1.35 \\ \cline{2-8}  & \(10^{2}\) & 25 & 217.5 & 1.8 & 3.4 & 6.40 & 4.55 & 1.40 \\ \cline{2-8}  & \(10^{1}\) & 30 & 217.8 & 1.8 & 3.4 & 6.4 & 4.6 & 1.4 \\ \hline \multirow{6}{*}{_Lacticaseobacillus rhamnosus_ (ppm)} & \(10^{8}\) & 5 & 123.2 & - & - & 3.85 & - & - \\ \cline{2-8}  & \(10^{5}\) & 10 & 138.0 & - & - & 4.45 & - & - \\ \cline{1-1} \cline{2-8}  & \(10^{5}\) & 15 & 142.3 & - & - & 4.55 & - & - \\ \cline{1-1} \cline{2-8}  & \(10^{4}\) & 20 & 145.4 & - & - & 4.85 & - & - \\ \cline{1-1} \cline{2-8}  & \(10^{4}\) & 25 & 147.6 & - & - & 4.90 & - & - \\ \cline{1-1} \cline{2-8}  & \(10^{2}\) & 30 & 147.6 & - & - & 4.90 & - & - \\ \hline \end{tabular}
\end{table} 
Table 3: Concentration (in ppm) of metabolites produced by _Levilactobacillus brevis_, _Lacitplantiobacillus plantarum_ and _Lacticaseibacillus rhamnosus_. Figure 6: The results of the antimicrobial activity of CFCs (after 5 days incubation) of three LAB species (_Levilactobacillus brevis, Lactiplantobacillus plantarum, Lactiaseibacillus rhamnosus_) against pathogenic bacteria _Salmonella enterica_ ATCC14028.