STUDIES OF L FORMS AND PROTOPLASTS OF GROUP A STREPTOCOCCI

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Abstract
Intact bacterial mem-branes were isolated from protoplasts prepared from group A streptococci by a cell wall-dissolving enzyme. A membrane fraction with identical chemical and serological properties was obtained by differential centrifugation of mechanically disrupted streptococci. The membrane is chemically and immunologically distinct from the cell wall and is composed of 72% protein, 26% lipid, and 2% carbohydrate. Evidence is presented which demonstrates that membranes isolated from protoplasts and from mechanically disrupted group A streptococci have identical chemical and serological properties. This bacterial membrane, largely a lipoprotein complex, is chemically and immunologically distinct from the cell wall. Immunodiffusion studies showed that this antigenic material is common to the membranes of group A streptococci, and can be distinguished from related antigenic substances present in membranes of other serological groups of hemolytic streptococci.