The role of electrostatic interactions in adhesion of Streptococcus thermophilus to human erythrocytes in media with different 1:1 and 2:1 electrolyte concentrations

Abstract

The process of bacterial adhesion is usually discussed in terms of a two-stage sorption model. According to this model, at the first stage bacteria rapidly attach to the surface by weak physical interactions, while at the second stage irreversible molecular and cellular adhesion processes take place. An important factor, influencing the adhesion processes, is physical and chemical characteristics of the medium, in particular, the presence of monovalent and bivalent cations. In this work, we assessed the role of electrostatic component of the intercellular interactions in the media with different electrolyte concentrations (namely, 1:1 and 2:1) at the first reversible stage of adhesion and probability of further specific binding. We compared experimental data of lactobacilli Streptococcus thermophilus adhesion to human erythrocytes with theoretical Debye radius and surface potential of erythrocytes in the experimental solutions of 1:1 electrolyte. Our results showed that with decreasing ionic strength of the solution, the change in the adhesion index in our experiments is fully in line with the theory DLVO (Derjaguin–Landau–Verwey–Overbeek) predictions. The experimental results were obtained and theoretical calculations of the electrostatic interactions parameters in the experimental solutions of 2:1 electrolyte once again confirmed the acceptability of a two-stage model of sorption and DLVO theory to describe a cell–cell adhesion.