## 3 Results and Discussion
### Cell Survival and Attachment of L. rhamns OIXAL-1 Cells through an In Vivo Mouse Model
\begin{table}
\begin{tabular}{c c c c c} \hline  & **CD** & **OD** & **ID** & **FD** \\ \hline Tissue & \multicolumn{4}{c}{Lactobacilli counts (log CFU/g)} \\ \hline Ileum & 5.02 \(\pm\) 0.19 a  & 5.04 \(\pm\) 0.15 a  & 5.82 \(\pm\) 0.18 b  & 5.84 \(\pm\) 0.11 b  \\ Cecum & 5.09 \(\pm\) 0.16 a  & 5.04 \(\pm\) 0.11 a  & 6.25 \(\pm\) 0.20 b  & 6.13 \(\pm\) 0.37 b  \\ Colon & 4.95 \(\pm\) 0.20 a  & 5.02 \(\pm\) 0.14 a  & 6.21 \(\pm\) 0.15 b  & 6.11 \(\pm\) 0.31 b  \\ \hline Intestinal fluid & & & & \\ \hline Ileum & 4.97 \(\pm\) 0.36 a  & 5.18 \(\pm\) 0.41 a  & 6.96 \(\pm\) 0.20 b  & 6.42 \(\pm\) 0.29 b  \\ Cecum & 6.93 \(\pm\) 0.22 a  & 6.95 \(\pm\) 0.18 a  & 7.97 \(\pm\) 0.18 b  & 7.64 \(\pm\) 0.16 c  \\ Colon & 6.94 \(\pm\) 0.14 a  & 6.88 \(\pm\) 0.14 a  & 8.01 \(\pm\) 0.16 b  & 7.54 \(\pm\) 0.24 c  \\ \hline \end{tabular}
\end{table} 
Table 2: Populations (log CFU/g) of lactobacilli in BALB/c mouse intestinal tissue and fluid samples after the administration of freeze-dried free or immobilized \(L\). _rhammosus_ OXLAL-1 cells on oat flakes. Figure 4: Levels (log CFU/g) of lactobacilli in BALB/c mouse feces before (day 0) and after (day 10) the administration of freeze-dried free or immobilized \(L\). _rhammosus_ OXLAL-1 cells on oat flakes. Data are expressed as mean \(\pm\) SD (n = 6 per group). * \(p\) \(<\) 0.05 compared to day 0; ** \(p\) \(<\) 0.05 when comparing ID vs. FD groups (day 10). CD: animals that received the control diet; OD: animals that received the control diet supplemented with a daily dose of 2 g of freeze-dried oat flakes; ID: animals that received the control diet supplemented with a daily dose of 2 g of freeze-dried immobilized \(L\). _rhammosus_ OXLAL-1 cells on oat flakes; FD: animals that received the control diet supplemented with freeze-dried free \(L\). _rhammosus_ OXLAL-1 cells. of _L. rhamnus_ cells when exposed to in vivo GI transit due to the increased lactobacilli counts in group ID compared to group FD. As a next step, and in order to confirm that the observed rise of lactobacilli counts in groups ID and FD occurred as a result of _L. rhamnus_ OLXAL-1 cells administration, a molecular analysis based on multiplex PCR methodology was applied (Figure 5). The presence of _L. rhamnus_ cells was confirmed based on species-specific primers for the _Lacticaseobacillus rhamnus_ group by targeting the _mutL_ locus and utilizing _Lacticaseobacillus hhamnosus_ GG as the reference strain. PCR products of 801 bp confirmed the presence of _L. rhamnus_ cells at levels > 6 log CFU/g in mice feces only in groups ID and FD at day 10 of the experimental protocol, further indicating the survival of the administered cells. Previous studies which evaluated the viability of LAB cells after GI transit using an in vivo BALB/c mouse model have reported similar results regarding the increase in lactobacilli counts in mice feces. [PERSON] et al. [46] investigated the viability of two _Lacticaseobacillus rhamnus_ (M1 and RHM) and four _Lactiplantiobacillus plantarum_ (M8, a7, LF57 and PIF) strains and reported that after 7 days of daily oral administration (1 \(\times\) 10\({}^{9}\) CFU per day) the number of LAB increased significantly compared to baseline, reaching levels > 7 log CFU/g of mice feces in all cases. Accordingly, [PERSON] et al. [47] studied the daily oral administration of _Lacobacillus kefiranofaciens_ DN1 (2 \(\times\) 10\({}^{8}\) CFU per day) to 4-week-old pathogen-free female BALB/c mice for a consumption period of 2 weeks and reported a  
Figure 5: Presence of _L. rhamnus_ at levels > 6 log CFU/g by multiplex PCR in fecal samples before and after the implementation of the 10-day dietary intervention protocol. Lane M: 1 kb DNA ladder (Takara, Shiga, Japan); Lane 1: PCR amplified product from a pure culture of _L.