Adhesion of Dextran to Streptococcus muttans

Abstract

Summary: Fifteen strains of Streptococcus mutans were agglutinated by 5 to 50 ng Leuco-nostoc dextran/ml, and one by 500 ng/ml. Competitive inhibition of the agglutination by sugars or sugar alcohols suggested that the spatial arrangement of the HOC(3)H and O(1) groups were important in the dextran but that the dextran receptor is not identical with the dextran reactive site of glucosyl transferase. Periodate oxidation of the dextran, with or without subsequent borohydride reduction, prevented agglutination, again implicating the C3 group. Pretreatment of dextran with cyclohexyl-isocyanide or of S. mutans with 4.0 m-urea, 0.01 m-EDTA or 0.1 % sodium dodecyl sulphate prevented agglutination; the last three reagents dispersed organisms already agglutinated. Ca2+ or Mg2+ reversed the effect of EDTA. Exposure of bacteria to 60°C or to papain for a few minutes impaired agglutination, so the dextran receptor site may be protein.