NUTRITION AND THE ROLE OF REDUCING AGENTS IN THE FORMATION OF STREPTOLYSIN O BY A GROUP A HEMOLYTIC STREPTOCOCCUS

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Abstract
A defined medium that supports growth and the formation of high titers per total cell population of the oxygen-labile hemoly-sin, streptolysin O, by Richards'' streptococcus (group A, type 3), has been developed. The minimum vitamin requirements for growth are supplied by nicotinic acid, pantothenate, and ribo-flavin. Addition of thiamine results in an increase in total growth and a 4-fold increase in the streptolysin O formed per unit cell population. In this medium, growth is independent of the presence of added reducing agents. Streptolysin O is produced, however, only in the presence of glutathione, cysteine, sulfite, hydrosul-fite, or thioglycolate. Each of these compounds shows an optimum concn. for lysin formation, above which the toxin titer drops sharply while growth remains optimum. The presence of ascorbic acid also permits streptolysin O formation. The lysin response per unit cell population is maintained at high level until the concn. of the acid inhibits growth. These results suggest that an optimum reducing potential is required for maximum lysin production.