1887

Abstract

The cells of Actinomyces viscosus ATCC 19246 (Av 19246) and Streptococcus sanguis ATCC 10557 (Ss10557) coaggregated immediately after mixing in 40 mM-Tris/HCl buffer. Optimal conditions were pH 7-5 in the presence of Ca at 0.1 mM or higher. Na EDTA and its analogues, NaMgEDTA and NaMnEDTA at 7.5 mM inhibited the coaggregation. Trypsin and heat treatment impaired the reactive site on Avl 9246 cells, but not on Ss10557 cells. The coaggregates, once formed, dissociated gradually during extended incubation at 37 °C; this was prevented by addition of sufficient Ca. The disaggregation appears to be a spontaneous denaturation of the proteinaceous reactive site on Av 19246 cell surface. Thus, the coaggregation involves the interaction of a lectin-like substance on the surface of Av 19246 with a carbohydrate site on Ss10557. Native Ss10557 cell walls possessed reactivity with Avl9246 cells but 5% (w/v) TCA-extracted cell wall residues did not. A carbohydrate moiety extracted from Ss 10557 exhibited a high potency in blocking coaggregation, and coaggregates were dissociated upon addition of the carbohydrate. Lactose, galactose and -acetyl-D-galactosamine (the latter two are major constituents of the antigen extract) also significantly inhibited the coaggregation, but the other antigen components, glucose and rhamnose, did not. Relative inhibitory activity, expressed as molar potency, of carbohydrate antigen, lactose, galactose and -acetyl-D-galactosamine respectively, was approximately 26 × 10:16:4:1. Ss10557 cells and cell walls reacted only with a (castor bean) agglutinin-120 but not with (soybean) agglutinin, (peanut) agglutinin or agglutinin (phytohaemagglutinin). These results suggest that the reaction site on Ss 10557 cells comprises a D-galactose-(1→4)-β-D-glucose- sequence and that N-acetyl-D-galactosamine (an immuno-determinant of the streptococcus strain) appears not to be involved in the coaggregation reaction.

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/content/journal/micro/10.1099/00221287-130-6-1351
1984-06-01
2019-10-15
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