## 3 Results
### Ability to Form Mono-Species Biofilms  
The mean OD values obtained by the quantitative biofilm production and morphotype of _Salmonella_ strains (five serotypes) are shown Table 2. Overall, 95.6% of the _Salmonella_ strains (five serotypes) were strong biofilm producers (mean, 1.100 \(\pm\) 0.027), while 4.3% were weak biofilm producers (mean, 0.016 \(\pm\) 0.002). The OD\({}_{570}\) results showed that the _Salmonella_ serotype influences the biofilm formation capacity on polystyrene (\(p\) < 0.05). Furthermore, a low PCC (0.121) is found between the _Salmonella_ serotype biofilm and multidrug resistance. Notably, 59.3% of the _Salmonella_ strains (five serotypes) showed the rdar morphotype, 2.1% pdar, 27.4% bdar, and 10.9% saw at both temperatures (22 and 35 \({}^{\circ}\)C) in CRA. In the detection of _Salmonella_ serotype morphotypes, temperature was not observed to have a significant influence on any of the tested microorganisms (\(p\) > 0.05). However, there is a medium PCC (0.453) between the _Salmonella_ serotype morphotypes and multidrug resistance. According to the results reported in Tables 1 and 2, four _Salmonella_ strain isolates (_Salmonella_ Rubislaw-1, _Salmonella_ Newport-6, _Salmonella_ Typhimurium-8, and _Salmonella_ Infantis-9) were selected among all the 91 examined strains based on the obtained biofilm formation values (ODs), multidrug resistance, and morphotype (Table 3). However, _Salmonella_ Oranienburg strains (\(n\) = 3) are saw and weak biofilm producers. Additionally, the four _Salmonella_ strains selected in this study showed a high ability to develop biofilms in the two culture medias (TSBS and TSBA), reaching more than 7.78 \(\log_{10}\) CFU/cm\({}^{2}\) (Table 4). In TSBS and TSBA, _Salmonella_ Infantis-9 had a significative difference (\(p\) < 0.05) in the cell density under the tested conditions; however, _Salmonella_ Newport-6, _Salmonella_ Typhimurium-8, and _Salmonella_ Rubislaw-1 did not have differences in their populations (\(p\) > 0.05). In contrast, in TSBA _Salmonella_ Rubislaw-1 had the lowest cell density (7.8 log\({}_{10}\) CFU/cm\({}^{2}\)) in comparison to the other serotypes, while _Salmonella_ Infantis-9 had the highest cell density (9.6 log\({}_{10}\) CFU/cm\({}^{2}\)) in comparison to its population in TSBS. In addition, the observed cells were irreversibly attached, and microcolonies of metabolically active cells were found in the mono-species biofilms of _Salmonella_ serotypes on PP, as well as EPS (extracellular polymeric substances) or organic matter from TSBS or TSBA medium by epifluorescence microscopy (Figure 2A-H). SEM analysis of representative mono-species \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Morphotype CRA (\(n\) = 91)**} & \multicolumn{3}{c}{**Polystyrene Biofilm Formation (\(n\) = 91)**} \\ \cline{2-8}
**Strains** & **rdar** & **pdar** & **bdar** & **saw** & **Strong Biofilm Producers** & **Weak Biofilm Producers** & **OD\({}_{\mathbf{570}}\)******* \\ \hline _Salmonella_ & & & & & & & \\ Rubislaw (\(n\) = 17) & 6 & 2 & 6 & 3 & 16 & 1 & \(\pm\) 0.25 \\ \hline _Salmonella_ & & & & & & & \\ Newport (\(n\) = 17) & 11 & - & 4 & 2 & 17 & - & \(\pm\) 0.01 \\ \hline _Salmonella_ & & & & & & & \\ Infants (\(n\) = 40) & 24 & - & 14 & 2 & 40 & - & \(\pm\) 0.11 \\ \hline _Salmonella_ & & & & & & & \\phimurium (\(n\) = 14) & 13 & - & 1 & - & 14 & - & \(\pm\) 0.00 \\ \hline _Salmonella_ & & & & & & & \\ Oranienburg (n = 3) & - & - & 3 & - & 3 & \(\pm\) 0.00 \\ \hline \hline OD\({}_{570}\)***** values \(\pm\) SDs obtained by polystyrene biofilm formation assays; rdar, red, dry, and rough colony; pdar, pink, dry, and rough colony; bdar, brown, dry, and rough colony; saw, smooth and white colony; OD, optical density; CRA, Congo red agar.** \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Morphotype of _Salmonella_ strains (five serotypes) and their biofilm production ability (\(n\) = 91). biofilms showed that cells were linked to each other and embedded in dense EPS or organic matter from TSBS medium (Figure 3A-D).