# Characterization and Selection of _Lactobacillus_ Strains with Potential Robotic Applications
## 3 Results and Discussion
### Adhesion Ability of Lactobacillus Strains to Intestinal Cells  
The ability of potential probioticic strains to adhere to intestinal cells is regarded as an essential criterion for probioticic selection. This biological feature allows them to colonize the mucous membrane of the intestines and exert their immunomodulatory effects. Adhesion is a complex process that is mediated by nonspecific physico-chemical interactions between the bacterial and host cell surfaces or through specific interactions between cell components, such as exopolysaccharideacharides, mucus-binding proteins (MUBs), surface layer proteins (Slps) and surface layer-associated proteins (Slaps). The adhesion of lactobacillus is a strain- and species-dependent property and can be influenced by various factors, including the cell line type [54]. In order to investigate how the isolated _Lactobacillus_ strains adhered to intestinal cells in comparison to the reference strain, they were cultured overnight with shaking and analyzed via an adhesion assay. In all strains, we observed lower adhesion to swine intestinal cells IPEC-J2 compared to the reference strain _L. casei_ ATCC 393, which is known as an important probiotic strain widely used in the dairy sector [55]. The highest degree of adhesion of the studied isolates was observed in _L. casei_ RC-1--39.45%, followed by _L. rhamn_s RC-10--23.38%. The lowest degree of adhesion was observed in _L. acidophilus_ RC-2--19.25% in comparison with the reference probiotic strain (Figure 7). [PERSON] et al. [42] investigated the probiotic properties of seven _Lactobacillus_ strains, including _L. brevis_ (B2 and B3), _L. acidophilus_ (B14, B15 and B17), _L. plantarum_ (B20) and _L. casei_ (B22) isolated from Iranian cheese, and used _L. rhamn_s GG as a reference strain. The results from the adhesion test demonstrated that all of the studied isolates were able to adhere to the human Caco-2 cell line with percentage rates varying from 2.5% (_L. brevis_ B3) to 14.6% (_L. acidophilus_ B14). The strain _L. rhamn_s GG showed an adhesion rate of 15%. These values were lower in comparison with our results. In another study by [PERSON] et al. [46], _L. casei_ ATCC 393 showed an adhesion rate of 51.8% to the human intestinal epithelial cell line HT-29, whereas the adhesion value for the strain _L. acidophilus_ ATCC 4356 was 29.3%. Using the same cell line (HT-29), [PERSON] et al. [56] determined that the adhesion rates of four _L. rhamn_s strains (LR013, LR019, LR087 and LR093) isolated  
Figure 7: Adhesion of _Lactobacillus_ strains to the IPEC-J2 cell line. All strains were grown O/N and incubated for two hours with IPEC-J2 cell monolayers in MRS+DMEM in MOI 100. All results were normalized to reference strain _L. casei_ ATCC 393 adhesion. Statistical differences between the strains were analyzed by one-way ANOVA and presented as geometric means. ***\(p<0.001\), ***\(p<0.0001\), \(n=3\). from cheese were between 4 and 9.5%. [PERSON] et al. [22] investigated the adhesive capacity of three _L. casei_ strains (SB71, SB73 and SB93) and found that all strains adhered well to Caco-2 cells, with ratios of 32%, 38% and 45%, respectively. In contrast, [PERSON] et al. [57] determined the high adhesion ability of the strain _L. rhamn_s SD4 to Caco-2 and human oral keratinocyte cell line H357, which showed adhesion rates of 76% and 89%, respectively. [PERSON] et al. [58] reported that the adhesion capacity of three _L. rhamn_s strains (WEI-17, WEI-30 and WEI-41) isolated from the intestinal mucosa of healthy piglets to the IPEC-J2 cell line varied between 54% and 78%. Considering the adhesion ability and the results of additional tests, the authors concluded that the studied strains possessed probiotic potential. The adhesion affinity to epithelial cells is a property typical not only for the gut lactobacilli but also for those inhabiting the female urogenital tract (vagina). In this regard, [PERSON] et al.