## 3 Results
### Characterization of Probiotic Candidate Lactic Acid Bacteria  
Probiotic bacteria have the capacity to produce various bioactive compounds that possess the ability to inhibit the proliferation of pathogenic bacteria. Probiotic microbes are the primary source of LAB. The probiotic candidates underwent characteristic testing in order to provide further evidence for the previously shown antibacterial activity, wherein the DK1 isolates exhibited the most prominent clear zones. In order to flourish within the gastrointestinal system, probiotic bacteria must possess antibiotic properties and exhibit resistance to low pH levels (2-3) as well as bile salts [22]. In addition, it is imperative to assess the capacity of probiotic bacteria to engage in auto-aggregation, which refers to the aggregation with similar bacteria, as well as co-aggregation, which pertains to the aggregation with dissimilar bacteria. This examination is crucial for their viability within the gastrointestinal tract and their ability to counteract harmful bacteria [23]. The bacteria DK1, referred to as the control isolates, were grown in MRSB media and incubated at 37 \({}^{\circ}\)C for a duration of 24 h. The results of the LAB characterization test demonstrated that the bacterial isolate DK1 exhibited the ability to thrive in an environment with a bile salt content of up to 7.99 log CFU/mL, as depicted in Figure 1.  
In addition, the DK1 bacterial isolates have been seen to exhibit resilience to acidic pH conditions, with the ability to survive at pH values as low as pH 2 and up to 6.15 log CFU/mL. Additionally, the results indicated that the bacteria exhibited a production of six logarithmic colony-forming units per milliliter (log CFU/mL) at temperatures of 25 \({}^{\circ}\)C, 37 \({}^{\circ}\)C, and 45 \({}^{\circ}\)C. The DK1 isolates exhibited a commendable performance on the auto-aggregation test, achieving a score of 89.2% (Table 3).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Code**} & \multirow{2}{*}{**Bacteria**} & \multicolumn{2}{c}{**Inhibition Zone**} & \multirow{2}{*}{**Inhibitory Activity Level**} \\  & & **Diameter (mm)** & \\ \hline \multirow{2}{*}{ DK1} & _Salmonella_ sp. & 11.5 \(\pm\) 0.71 & Moderate \\ \cline{2-4}  & _E. coli_ & 13.0 \(\pm\) 1.41 & Strong \\ \hline \multirow{2}{*}{ DK2} & _Salmonella_ sp. & 9.5 \(\pm\) 1.41 & Moderate \\ \cline{2-4}  & _E. coli_ & 8.5 \(\pm\) 0.71 & Weak \\ \hline \multirow{2}{*}{ DK3} & _Salmonella_ sp. & 8.0 \(\pm\) 0.00 & Weak \\ \cline{2-4}  & _E. coli_ & 8.5 \(\pm\) 1.41 & Weak \\ \hline \end{tabular}
\end{table}
Table 2: The results of CFS antimicrobial activity test, 294 \(\times\) 123 mm (38 \(\times\) 38 DPI).  
In order to establish a presence and thrive within the gastrointestinal tract, probiotic bacteria must possess the ability to undergo auto-aggregation [23]. _Salmonella_ sp. and _E. coli_ bacteria were utilized in co-aggregation investigations. The co-aggregation test results demonstrated a higher percentage of co-aggregation with _E. coli_ bacteria (53.1%) compared to _Salmonella_ sp. (46.9%) (Table 3). Certain pathogenic bacteria and lactic acid bacteria possess the ability to induce coagulation, hence facilitating the release of antibiotic substances into the targeted cells of the pathogens. This mechanism allows the bacteria to effectively control the growth and proliferation of potentially pathogenic bacteria in close proximity [23]. Co-aggregation has the potential to hinder the colonization of harmful bacteria on the intestinal mucosa, while also facilitating the production of antibiotic substances, hence enhancing the eradication of pathogenic microorganisms from the digestive system.