The relationship of streptolysin S (SLS) and a cellular potential hemolysin (PH) activatable by sonication was examined in strain C203S (a known high producer of SLS), its SLSmutant (C203U), and in 20 other group A streptococci of various M and T serotypes. All strains shown to form SLS (ribonucleic acid [RNA]-core SLS) contained PH. The two strains lacking PH were the only ones that did not produce SLS. In strain C203S, formation of SLS by cells incubated with RNA-core for 60 min at 37 C in a nongrowth basal medium (Bernheimer's basal medium) was followed by a marked decrease (99.6% loss) of PH titer. Without stimulation of SLS production by addition of RNA-core, the same incubation resulted in a progressive but less marked fall (38.8% loss in 60 min) of PH titer: these cells produced disproportionately low titers of SLS on subsequent addition of RNA-core. This effect of prior incubation in Bernheimer's basal medium on SLS titer was partially nullified by use of fresh medium after 30 min, but not after 60 min, and did not occur during 60 min of incubation at 0 C. These results provide additional evidence for a precursor-product relationship between PH and SLS. They also suggest that a medium factor (or factors) is utilized or destroyed at 37 C and that this factor is essential to both the stability of PH and its efficient conversion to SLS.

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Cellular potential hemolysin, the precursor to extracellular streptolysin S, was activated by grinding with glass beads on a Vortex mixer. Hemolysin activity was markedly enhanced by the addition of ribonucleic acid-core during the grinding. Determinants for optimum results with the beads included small bead size, prewashing of beads with acetic acid, and appropriate bead volume during grinding. The increased sensitivity of this technique over those previously used revealed cellular potential hemolysin in cells grown in the presence of glucose, which inhibits streptolysin S production. The basis for the increased sensitivity of this procedure may be due to the binding of cellular potential hemolysin or ribonucleic acid to the beads.

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