Kinetic Analysis of Streptococcus sanguis Adhesion to Artificial Pellicle

Abstract

Studies of equilibria between Streptococcus sanguis and artificial pellicle have suggested that there are multiple binding sites for the organism. In the present study, adhesion of S. sanguis to saliva-coated hydroxylapatite was examined by means of kinetic methods. Cell-pellicle complex formation was measured from initiation of binding to equilibrium. Rate constants were calculated for forward reactions (adsorption) and reverse reactions (desorption). Initial binding obeyed reversible, first-order kinetics, whereas desorption of bound cells followed biphasic kinetics. Initial desorption proceeded approximately ten times faster than the slower second rate. The results are consistent with the mechanism C + P reversible CP* in equilibrium with CP in which CP* represents the reversible equilibrium that shifts at a discrete rate to the high-affinity CP state. Thus, the biphasic binding behavior that has been previously deduced from equilibrium studies may be attributed to a time-dependent shift from close apposition to pellicle, stabilized by low-specificity forces, to a higher-affinity binding.

Energetics of the initial phase of adhesion of Streptococcus sanguis to hydroxylapatite

“…This suggests that the initial encounter with the pellicle substratum is slow enough to be studied and slow enough to be inhibited. Whereas sialic acid probably has a role in'the binding reaction (12), the initial binding equilibrium seems to be largely independent of a specific high-affinity receptor (8). The rate constants for adsorptiQn and desorption in this initial equilibrium show a marked dependence on temperature.…”

“…However, that specificity has been difficult to define, and it is believed that multiple forces govern adhesion (10)(11)(12). Kinetic studies suggest that S. sanguis passes through two distinct binding transitions (8). The first stage is a reversible one described by pseudofirst-order rate constants for adsorption and desorption.…”

“…Beads were prepared for the adsorption and desorption experiments as described previously (8). Spheroidal hydroxylapatite beads (25 mg) were rinsed in distilled water and then rotated in buffered KCl.…”

“…A detailed description of the conditions for adsorption and desorption is provided elsewhere (8). For adsorption experiments, a radiolabeled suspension of S. sanguis cells was added to a series of vials containing bare hydroxylapatite (HA) or saliva-coated hydroxylapatite (SHA).…”

An analysis of the biofilms adhered to framework alloys using in vitro denture plaque models

“…Therefore, the biofilm form on the different pellicles might be different for different types of samples. In addition, it has been suggested that the adhesion of bacteria is affected by various factors, such as the differences in the charge of the surface layer of the bacteria 70) , van der Walls and electrostatic forces, hydrophobicity and the presence of lectin ligands 71) . Another study will be necessary to understand the reasons why S. mutans adhered more to Co-Cr than the other alloys.…”