Adherence capacities of oral lactobacilli for potential probiotic purposes

The most abundantly used probiotic strains come from the genus Lactobacillus and only a few studies have investigated their role in oral health. Even if a positive correlation has been established between the saliva Lactobacillus count and dental caries, this genus is generally recognized as safe (GRAS). Moreover, lactobacilli could in some cases play a beneficial role by inhibiting the growth of some oral pathogenic bacteria. This activity could justify their use as probiotic. To establish the potential health benefit of probiotic candidates, appropriate in vitro tests are required, particularly on their adhesive capacity. The aim of this work was to investigate the adhesive properties and surface characteristics of 70 oral lactobacilli that could be used as probiotics for oral health. For this, three methods were used: biofilm formation on a glass surface and on saliva-coated hydroxyapatite discs and the microbial adhesion to solvent method. The results of the biofilm formed on glass surface showed 13 strains with an adhesion score equal to or higher than 3. 57/70 (81%) of the tested lactobacilli did not form any biofilm on glass surfaces. All of the 13 strains formed biofilms on HA discs. Among these 13 strains, 10/13 (77%) showed low surface hydrophobicity (0-35%) and 3/13 (23%) showed medium hydrophobicity (36-70%). Some of the selected strains showed potentially useful adhesive capacity. This work paves the way for the selection of probiotics that could be used for oral health purposes with the aim to reduce carious risk.