Oral Colonisation Potential of Probiotic Lactobacilli and Bifidobacteria in vitro

Objectives: Health-promoting probiotic bacteria in food products are potential colonisers of the mouth. We investigated this potential of different Lactobacillus and Bifidobacterium strains by testing their adherence on buccal epithelial cells (BEC) and on saliva- and Fusobacterium nucleatum-coated hydroxyapatite (HA) in vitro. Methods: Two probiotic, one dairy and two faecal Lactobacillus strains and one probiotic and one faecal Bifidobacterium were included in this study. The adherence on saliva and / or saliva- and F. nucleatum-coated HA was examined by allowing the labelled bacteria to adhere for 1h on HA beads coated with either pooled, clarified whole saliva or with saliva and F. nucleatum. The adherence on BEC was determined by mixing suspensions of BEC and bacteria. After 1h incubation and washes BECs with attached bacteria were fixed on glass, stained and the number of bound bacteria was counted. Results: Of the tested lactobacilli three adhered well on saliva-coated HA, over 40 % of the added bacteria were bound. The remaining two lactobacilli and the bifidobacteria did not adhere on saliva-coated apatite. F. nucleatum-coating enhanced the adherence of the bifidobacteria on HA. The adherence of the low binding lactobacilli was also slightly better on F. nucleatum-coated apatite than to the saliva-coated apatite. The opposite happened with the lactobacilli that adhered well on saliva-coated apatite - F. nucleatum coating diminished clearly their adherence. Two of the Lactobacillus strains attached well on buccal epithelial cells (15 bacteria / cell), the others did not adhere to BECs. Conclusion: Differences in the adhesion of different (probiotic) lactobacilli and bifidobacteria on HA coated with either saliva or F. nucleatum, and on buccal epithelial cells, may affect the oral colonisation potential of these bacteria. The effects of probiotics on oral ecology are still unknown. Supported by the Turku University Central Hospital.