Synergistic Degradation of Transferrin by Mutans Streptococci in Association with other Dental Plaque Bacteria

Abstract

Streptococcus mutans strains Ingbritt and NCTC 10449 and S. sobrinus strains K 1 and SL1 exhibited low, but measurable, ability to degrade human transferrin, a serum-derived glycoprotein. However, when incubated in the presence of other members of the supragingival dental plaque miciroflora, synergistic degradation of transferrin was observed. S. oralis and Fusobacterium nucleatum were most effective, giving rise to levels of degradation up to 3-fold above those observed with either bacterium singly; Actinomyces viscosus gave rise to lower levels of synergy. Combinations of one strain of mutans streptococci with two other strains of dental plaque bacteria gave rise to levels of transferrin degradation which were up to 2–4-fold greater than those of individual bacteria. Supragingival plaque bacteria elaborated a range of complementary glycosidase and peptidase activities which interact in the degradation of glycoproteins resulting in the observed synergistic effects.