## 2 Results and Discussion
### Enumeration Cell Death Over Time by Time-Kill Curve  
Time-kill assay of EOEP against the tested bacterial species was performed to determine the response on the growth pattern. Based on the MIC and MBC values, six concentrations of EOEP were tested against foodborne pathogenic Gram-positive bacteria, including _B. cereus_, _S. aureus_ and _L. monocytogenes_, at an initial concentration of ca. 3 log CFU/mL. The bacterial viable cells were enumerated over time to investigate their response to the antimicrobial agent, as shown in Figure 3. The bacteriostatic (the concentration where the bacterial culture remains constant) and bactericidal (the concentration where the bacteria dies at no viable count in 18h) concentrations can be determined from Figure 3[27]. All bacterial strains grew well in the control sample (non-selective media without the addition of EOEP). The cell numbers of _B. cereus_ and _S. aureus_ in the control (TSB without EOEP) reached 9 Log CFU/mL in 12 h, as shown in Figure 3A,B. When 0.01% EOEP was added to the broth medium, _B. cereus_ cells grew to 9 Log CFU/mL in 12 h, which was similar to the control. In 0.03% EOEP, the bacterial cell count remained constant at ca. 2 log CFU/mL for 12 h and then increased to 8 Log CFU/mL after 18 h. On the other hand, bactericidal effect was detected at an EOEP concentration of 0.05% as the number of cells gradually reduced to undetectable levels within 18 h. Furthermore, at a concentration of 0.15%, the number of _B. cereus_ cells became undetectable within 12 h. The response of _S. aureus_ to 0.01 and 0.03% EOEP was similar to _B. cereus_, as shown in Figure 3B. In the case where 0.05% EOEP was applied, it showed a bacteriostatic effect, as seen in the fact that the cell numbers remained constant at ca. 2 log CFU/mL throughout the study. At 0.10 and 0.15%, EOEP became bactericidal, and the number of cells reduced to undetectable amounts within 24 and 18 h, respectively. The response of _L. monocytogenes_ to EOEP was more sensitive than other species, as it showed bacteriostatic effect at 0.03% EOEP, and became bactericidal at 0.05% EOEP. The _listerial_ cell was completely inactivated at 0.10% EOEP within 24 h, as shown in Figure 3C. In summary, time-kill curves revealed the dynamic response of the bacterial cells on the growth pattern at an EOEP concentration of 0.01%, which showed an inhibitory effect against _B. cereus_, _S. aureus_ and _L. monocytogenes_ [PERSON] At a concentration of 0.03%, EOEP showed bacteriostatic effect and, at 0.1% or greater, EOEP showed lethal effect. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Tested Bacteria** & **MIC (\% \(\
u\)/\(\
u\))** & **MBC (\% \(\
u\)/\(\
u\))** \\ \hline
**Gram-Positive Bacteria** & & \\ _Bacillus cereus_ & 0.02 & 0.15 \\ _Staphylococcus aureus_ & 0.03 & 0.15 \\ _Listeria monocytogenes_ 101 & 0.02 & 0.15 \\ _Listeria monocytogenes_ 108 & 0.02 & 0.10 \\ _Listeria monocytogenes_ V7 & 0.02 & 0.30 \\ _Listeria monocytogenes_ Scott A & 0.02 & 0.10 \\ _Gram-negative bacteria_ & & \\ _Escherichia coli_ & 5.00 & 5.00 \\ _Pseudomonas aeruginosa_ & \textgreater{}5.00 & \textgreater{}5.00 \\ _Salmonella Typhimurium_ & \textgreater{}5.00 & \textgreater{}5.00 \\
**Lactic acid bacteria** & & \\ _Lactobacillus plantarum_ 541 & \textgreater{}5.00 & \textgreater{}5.00 \\ _Lactobacillus plantarum_ 844 & \textgreater{}5.00 & \textgreater{}5.00 \\ _Pediococcus cerevisiae_ & \textgreater{}5.00 & \textgreater{}5.00 \\ _Leuconostoc mesenteroides_ & \textgreater{}5.00 & \textgreater{}5.00 \\ \hline \hline \end{tabular}  
MIC = the lowest concentration of antimicrobial concentration required to inhibit the visible growth of bacteria tested in the test tube. MBC = the lowest concentration of antimicrobial concentration required to diminish at least 99.9% (3 Log reduction) of the initial bacterial amount at 24 h. The experiment was carried out in triplicate and the modal values are shown.  
\end{table}