Polysaccharide storage in different streptococci.

Calf serum, pooled human plasma, polyvinylpyrollidones (PVP) and polyethylene glycols (PEG) were required as medium components by many cultures of group A.S. pyogenes for intracellular polysaccharide accumulation. These supplements produced a stabilizing effect, probably at the cell surface, and were not associated with nutrition during intracellular iodophilic polysaccharide (IPS) storage. Medium stabilization and the presence of maltose or maltose yielding polysaccharides was found to be a property unique to the group A streptococci. Cariogenic streptococci and Streptococcus agalactive did not require medium stabilization for IPS storage although addition of PVP or PEG was stimulatory. Different degrees of IPS storage in group A.S. pyogenes was found to be strain related and probably dependent on the size and degree of branching of the storage polymer.