The components of the cell walls and extracellular slime of four strains of Staphylococcus salivarius isolated from human dental plaque

Abstract

Four strains of a Gram-positive coccus isolated from human dental plaque were identified as Staphyloccus salivarius. The inclusion of these organisms in the genus Staphylococcus was supported by cell wall studies. Examination of the acidic extracellular polysaccharide produced by the organisms revealed the presence of glucose, mannose, galactose, rhamnose, glucosamine, galactosamine, and several amino acids. Quantitative assays showed the similarity of the material produced by all four strains and that the amino sugars and rhamnose could not be derived from the whole cell wall contamination. Extraction of the polysaccharide with formamide and trichloracetic acid showed that the amino acids originated from mucopeptide fragments, possibly linked to the polysaccharide. Acid extraction of cell wall samples showed the presence of a polymer containing galactose and galactosamine; this polymer could account for the trace of galactose detected in the extracellular polysaccharide. Carboxylic acid groups were the most likely groups responsible for the acidic nature of the material. The type of compound carrying the caboxylic acid group could not be determined.