Effect of macromolecules on adherence of Streptococcus mutans

The influence of macromolecules on the adherence of S. mutans was studied in an in vitro incubation system using 3H-labeled bacteria and hydroxyapatite beads. The bacterial adherence was strongly inhibited by treating the beads with an extremely acidic macromolecule. An even more pronounced effect was found when this substance was present during the incubation. To the contrary no effect was discernible when the bacteria only were pretreated with the acidic macromolecule. Even the basic substance decreased the adherence of the bacteria but to a less extent. The bacterial surface has a net negative charge and attracts basic molecules while hydroxyapatite beads analogously appear to have a net positive charge and attract acidic macromolecules. This adsorption of macromolecules might be a phenomenon of importance for the microbial colonization of teeth.