Hemolysis

Hemolysis is the breakdown of blood, which certain bacteria can do. Bacteria that are capable of hemolysis are considered hemolytic and therefore pathogenic. Hemolysis is conventionally tested by using a blood agar plate.
There are three different kinds of hemolysis
Gamma hemolysis shows a lack of enzymes that breakdown blood. There is no color change in the color around the colony.
Beta hemolysis shows the complete breakdown of blood. The organism that shows Beta hemolysis excretes enzymes that creates a clear zone around them when observed. Examples of organisms that completely break down blood include Staphylococcus aureus and Streptococcus pyogenes.
Alpha hemolysis shows a partial breakdown of blood, and the zone around the colony is green. Some organisms that show alpha hemolysis are pathogenic like Streptococcus pneumoniae, while some are not.