The phenomenon of salivary protein adsorption onto Streptococcus mitis ATCC 903 cells

It is thought that salivary proteins on bacterial cells have some influence on the adhesion of oral bacteria onto the surface of oral tissues and on bacterial aggregation. Initially, this study sought to examine the phenomenon of salivary protein adsorption to the surface of Streptococcus mitis ATCC 903 using 3H-labeled salivary proteins. We investigated the effects of hydrophobic level and lectin-ligand binding on adsorption of salivary proteins, and also the influence of cell surface components on adsorption. The results showed that the adsorption of salivary proteins was clearly reduced by the presence of Tween 20, LiCl, NaSCN, Hexadecane and some sugars. The adsorption was also affected by the pH level, and protease treatment or heat treatment of cells also decreased the volume of adsorbed proteins. Although the adsorption of proteins onto heat-treated cells was dramatically reduced by the presence of LiCl and NaSCN, the presence of sugars had little influence on this adsorption. These findings suggest that the main adsorption of salivary proteins is due to hydrophobic factors, and the heat-sensitive surface components of the cells had some relation to lectin-ligand binding. Therefore, it appears important to study the adsorption of salivary proteins onto cells since the salivary proteins on bacterial cells play an important role in their adherence to the saliva-coated oral tissues and bacterial aggregation.