Examination of adhesive determinants in three species of Lactobacillus isolated from chicken.

The microbial adhesion process includes passive forces; electrostatic interactions; hydrophobic, steric forces; lipoteichoic acids; and specific structures, such as external appendages (lectins) and (or) extracellular polymers. In a previous work, we showed that Lactobacillus animalis, L. fermentum, and L. fermentum ssp. cellobiosus had lectinlike proteic structures on their surfaces and high hydrophobicity values on the cell surface of L. fermentum ssp. cellobiosus. Here, we examined the presence of the bacterial forces or structures that could be involved in the interaction between bacteria and epithelial cells. Lactobacillus animalis and L. fermentum possessed a net negative surface charge, whereas L. fermentum ssp. cellobiosus showed similar affinity to both cationic and anionic exchange resins, aggregated in the presence of ammonium sulfate, and had high affinity (75.4%) to a hydrophobic matrix. Only L. animalis was shown to have ribitol teichoic acids in the cell wall. The amount of polysaccharides from cell walls varied between different strains, with L. fermentum ssp. cellobiosus having the highest concentration. Lectin extracts obtained from lactobacilli did not possess sugar residues, thereby demonstrating the proteic nature of the superficial surface structures of three strains. The lactic acid bacteria studied here showed different surface determinants, which could be involved in the interactions between these lactobacilli and intestinal epithelial cells.

Some probiotic properties of chicken lactobacilli.

The beneficial effect of lactobacilli has been attributed to their ability to colonize human and animal gastrointestinal tracts. In this work, adhesion assays with three lactobacillus strains and intestinal fragments obtained from chickens were assessed. Lactobacillus animalis and L. fermentum were able to adhere to three kinds of epithelial cells (crop, small and large intestines) with predominance to small intestine. Among the strains considered, L. fermentum subsp. cellobiosus showed the lowest and L. animalis the highest adhesion ability. Scanning electron microphotographs showing L. animalis and L. fermentum adhering to intestinal cells were obtained. The characterization of L. animalis adhesion indicated that lectin-like structure of this strain has glucose/mannose as specific sugars of binding. However, a calcium requirement was not observed. The adhesion of L. fermentum was reduced by addition of sialic acid or mannose (P < 0.01). These carbohydrates can be involved in the interaction between adhesin and epithelial surface. In this case, the dependence on bivalent cations was demonstrated. Lactobacillus fermentum was effective in reducing the attachment of Salmonella pullorum by 77%, while L. animalis was able to inhibit (90%, 88%, and 78%) the adhesion of S. pullorum, S. enteritidis, and S. gallinarum to host-specific epithelial fragments respectively. Our results from this in vitro model suggest that these lactobacilli are able to block the binding sites for Salmonella adhesion.