CATALASE TEST
This test is used to differentiate those bacteria that produce the enzyme catalase, such as staphylococci, from non-catalase producing bacteria such as streptococci.
PRINCIPLE:
Catalase acts as a catalyst in the breakdown of hydrogen peroxide to oxygen and water.An organism is tested for catalase production by bringing it into contact with hydrogen peroxide. Bubbles of oxygen are released if the organism is a catalase producer. The culture should not be more than 24 hours old.
Care must be taken if testing an organism cultured on a medium containing blood because catalase is present in red cells. If any of the blood agar is removed with the colony, a false positive reaction will occur. It is usually recommended, therefore that catalase testing be performed from a blood-free culture medium such as nutrient agar.
REQUIREMENTS:
Hydrogen peroxide, 3% H2O2 -------- (10 volume solution)
METHOD:
· Pour 2-3ml of the hydrogen peroxide solution into a test tube.
· Using a sterile wooden stick or a glass rod, remove a good growth of the test organism and immerse it in the hydrogen peroxide solution.
· Look for immediate bubbling.
RESULTS:
Active bubbling……………………… Positive test
(Catalase produced)
No release of bubbles………………… Negative test
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