The Cellular Location of the Streptococcal Group D Antigen

Abstract

The cellular location of the group D antigen was examined by fractionation of protoplasts prepared by digestion of cell walls with lysozyme in an osmotically protective medium. The major portion of the group D antigen appears to be closely associated with the protoplast membrane of Streptococcus faecalis (atcc 9790). Some antigen was found in the supernatant fluid (lysozyme hydrolysate) after removal of the protoplasts. This was attributed to the known fragility of protoplasts and membranes.