Preparation of protoplasts of group H streptococci (Streptococcus sanguis)

Stable protoplasts of several strains of group H streptococci (Streptococcus sanguis) can be prepared by use of group C streptococcal phage-associated lysin in the presence of 30% raffinose. Sucrose cannot be substituted for raffinose. Protoplast formation did not require the addition of Mg2+; however, this cation enhanced their stability. Some other strains, also presumptive group H streptococci, were not sensitive to phage-associated lysin.