Actinomyces viscosus のグルカンによる菌体凝集の機序

抄録

The mechanism of glucan-induced agglutination of Actinomyces viscosus was investigated using strain ATCC 15987 as a main test organism. A. viscosus cells attached only slightly to the uncoated enamel surface of extracted human premolars, whereas the cells markedly attached to the cement surface. The attachment of A. viscosus cells to the enamel surface was markedly enhanced by covering the surface with an artificial plaque consisting of cells and glucans of sucrose-grown Streptococcus mutans.
This enhance attachment seemed to occur as a consequence of the agglutination of A. viscosus by the cell-associated glucan synthesized by S. mutans, because it was shown that a suspension of A. viscosus cells co-agglutinated with a suspension of sucrose-grown cells of S. mutans. The glucan agglutination of A. viscosus results from the binding of glucan molecules to a bacterial cell surface.
This agglutination activity of A. viscosus was shown to be lost when the cells were either digested with trypsin or heated at 100 C for 10mm, suggesting the protein nature of a glucan receptor site. Among a variety of polysaccharides examined, only high molecular weight glucans containing α-1, 6 bonds as the main glycosidic linkage exhibited the activity to agglutinate A. viscosus cells. A study with chemically modified dextrans has revealed that C₁-carboxylated dextran was active, but C₆-carboxylated dextran was inactive in inducing agglutination of A. viscosus, indicating the importance of nonreducing ends of the glucan in its attachment to the receptor of the cells.