Some Streptococcus groups are beta-hemolutic on blood agar, is it because of toxins? What toxins exactly causes the beta-hemolysis?
If it is then how are these toxins affected by the presence of oxygen and how it is regulated? Since they can be facultative anaerobes.
Thanks in advance.
I think oxygen helps Streptococcus hemolyzing blood.
GAS produce two hemolysins that may contribute to pathogenesis. Streptolysin O (SLO) is a well-characterized oxygen-labile prototype of a cholesterol-binding bacterial exotoxin. When cultured in broth, GAS express SLO during exponential-phase and early stationary-phase growth (1). Streptolysin S (SLS) is an oxygen-stable oligopeptide primarily responsible for the characteristic zone of beta-hemolysis surrounding GAS colonies grown on blood-agar medium (copied from Article Cytotoxic Effects of Streptolysin O and Streptolysin S Enhan...
)
Beta hemolysis on blood agar (complete lysis of red cells) indicates the production of hemolysin by the tested bacterium.
Streptolysins are two hemolytic exotoxins from Streptococcus.
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