Evaluation of adhesion properties of lactobacilli probiotic candidates

Bacterial adhesion is a complex phenomenon implicated in the host-bacterial interaction that is pivotal for probiotic activity. Eight probiotic lactobacilli candidates (Lactobacillus reuteri, L. plantarum, L. mucosae, L. murinus) were screened for their ability to adhere to abiotic and biotic surfaces in vitro. Adhesion to hydrocarbons was used for hydrophobicity assessment. Three strains of L. reuteri and L. murinus C were evaluated as hydrophobic, others as intermediate. All tested strains were able to form the biofilm on polystyrene. L. mucosae D and L. reuteri E were tested for adhesion to epithelial cell lines (HeLa and Caco-2). Both were more adherent to HeLa than to Caco-2. The adhesivity degree in HeLa reached the highest value after 8 h of co-cultivation in both lactobacilli tested, then decreased. In Caco-2, adhesion was increased within 24 h from the beginning of the co-cultivation. Mucus-binding protein gene, implicated in adhesion, was detected in L. mucosae D. Therefore, the involvement of proteinaceous substances in binding process was investigated. Cells of L. mucosae D were digested by three proteolytic enzymes (proteinase K, pronase E, trypsin) and evaluated for time-dependent adhesivity changes to HeLa, Caco-2, and L929 cell lines. Results confirmed that proteins are most likely to play an important role in binding of lactobacilli to eukaryotic cells. One hour after treatment, L. mucosae D was able to overcome the effect of proteolytic cleavage. We assume that it was due to the restoration of its cell-surface binding structures. Co-cultivation of HeLa and L. mucosae D led to protuberance and communication channels formation in eukaryotic cells. [GRAPHICS] .