Which statement describes Streptolysin S?

Streptolysin S is an important hemolysin produced by certain strains of Streptococcus pyogenes (Group A Streptococcus). This molecule is characterized by its oxygen stability, meaning that it remains functional in the presence of oxygen. However, it is most effective in environments where oxygen levels are low, such as anaerobic conditions. This makes it a potent factor in the pathogenicity of Streptococcus species, as it can lyse red blood cells and facilitate the bacteria’s growth in tissues where oxygen is limited.

This functionality is significant in understanding how certain bacteria can thrive in diverse environments, especially those that are not conducive to other organisms. Therefore, the characteristic of being optimal in anaerobic conditions highlights how Streptolysin S is adapted to enhance bacterial survival and virulence. In contrast, Streptolysin S is not oxygen labile, which rules out the first option, and it is clearly not completely inactive, nor is its role limited to merely inhibiting bacterial growth. Its primary action is lytic, contributing to both the bacteria’s nutrient acquisition and their pathogenic effects.