Identification of Penicillin-Stimulated Staphylococcal Haemolysin as Alpha-Lysin

Cultivation of S. aureus in the presence of 0.03 IU benzyl‐penicillin stimulated the formation of a haemolysin which was suggested to be alpha‐lysin. Its molecular weight was estimated to be 30000 by molecular sieve chromatography. It was mainly active on rabbit erythrocytes and was neutralized by alphalysin antibody. Furthermore it gave a reaction of identity in comparative immunoelectrophoresis with an are which was shown to represent alpha‐lysin.