Catalase test test is used to identify microorganisms that produce catalase enzyme. It is used to differentiate catalase-producing organisms (e.g. Staphylococcus species) from non-catalase producing bacteria (e.g. Streptococcus species). Catalase enzyme breakdown hydrogen peroxide (H2O2) to water and oxygen.
2H2O2 ———> catalase ———>> 2H2O + O2
Most aerobic bacteria produce possess catalase enzyme in varying amounts except the lactic acid bacteria which do not produce the enzyme in detectable amounts. Obligate anaerobes are usually catalase negative. Hydrogen peroxide is a highly toxic product of certain cellular processes such as the reduction of flavoproteins, thus catalase test is used to determine whether or not a particular microorganism produces catalase (the enzyme that catalyzes the breakdown of H2O2). This test can be performed by two methods: the slide method and the test tube method, but only the slide method shall be expanded here.
- Perform this test with pure culture from culture media plate (preferably BA).
- Place a loopful or speck of the test organism on a clean glass slide.
- Emulsify the culture with a loopful of freshly prepared H2O
- Lookout for the release or presence of bubbles which indicates a catalase positive result. The bubbles results from the production of oxygen gas released from theaction of catalase enzyme (produced by the test organism) on the H2O2.
Illustration of catalase test
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