This thesis has sought to characterize some of the factors that influence the production, purification and toxicity of streptolysin S (SLS) from Streptococcus pyogenes group A. Two strains, C203S and 55903M, were examined for the production of SLS. Of these, C203S produced the highest yield. Production of the lysin in brain heart infusion broth (BHI,Difco) supplemented with 1% (w/v) maltose and 2% (w/v) sodium bicarbonate (BHI-BM), was maximal between the early and late exponential phases of growth. SLS production was examined in both strains grown in BHI-BM (Oxoid) and BHI-BM (Difco). Cultures in the latter medium gave the higher yields of SLS. For intensive production of SLS, a procedure involving fourteen "inductions" was carried out on the same pellet of bacteria, which was repeatedly resuspended in induction buffer and stimulated each time with RNA-core, SLS was synthesized de novo during each induction cycle, and inhibitors of protein synthesis such as chloramphenicol blocked its formation. The combined material from the 14 inductions (crude SLS) was further purified by hydroxylapatite column chromatography. The purified product had a specific activity of 3.5X10
