<prompt> Streptolysin O is inactivated byCO2NitrogenOxygenSerum  <response>: Streptococci produce 2 types of Streptolysin OS based on oxygen dependency. Streptolysin O is oxygen labile. It is inactive in the presence of Oxygen. Streptolysin O is antigenic and ASO titre is a standard serological diagnosis of Acute Rheumatic fever. Streptolysin O S both can cause hemolysis. 