Binding of oral veillonella species to saliva-coated hydroxyapatite

Abstract

Veillonella spp. are found in high numbers in the mouth in dental plaque and on the mucosa. Veillonellae utilize lactic acid for their metabolic needs. A symbiotic relationship between Veillonellae and other oral bacteria, including a nutritional relationship with some streptococci, has been demonstrated both in vitro and in vivo. Thus, Veillonellae may protect the host from dental caries. Adherence is the initial step in bacterial colonization of oral surfaces. Recent evidence suggests that certain oral bacteria express molecules (adhesins) on their cell surface, which recognize receptors on other oral bacteria and/or in salivary pellicle. It has been previously demonstrated that Veillonella spp. bind avidly to Streptococcus. spp. found in subgingival plaque. The present study investigated the ability of V. atypica PK1910 to bind to saliva-coated hydroxyapatite (SHA), a model for adherence to the salivary pellicle. The results show that there was statistically significant enhanced binding of Veillonella atypica PK1910 to saliva-coated hydroxyapatite beads. (p< 0.05) Three classes of coaggregation-defective mutants of V. atypica PK1910 were tested for their ability to bind to SHA. Interestingly, they did not demonstrate any enhanced binding to saliva-coated hydroxyapatite beads. Heating of PK1910 did not effect binding to SHA. In contrast, protease treatment of the veillonella cell surface inactivated binding. Therefore, it appears that V. atypica PK1910, in addition to binding to oral Streptoccoccus spp. in dental plaque, may also colonize the tooth surface by binding directly to the salivary pellicle. It appears that a distinct heat stable protein may mediate this binding to SHA.