Catalase Test
Catalase is enzyme which breaks down hydrogen peroxide into oxygen and water. One of the oxidative end products that are produced by aerobic carbohydrate metabolism is hydrogen peroxide. If hydrogen level is too high for bacterial cells, it will kill them.
In this case, the catalase test that is uses to differentiate Neisseria gonorrhoeae and other Neisseria and related Species. ( Kingella denifrificans)
Catalase converts hydrogen peroxide into water and oxygen shown by the following reaction:
catalase
2(H2O2) --------> 2(H20) + O2 (Gas bubbles)
Method
1. A small drop of the hydrogen peroxide solution was dropped onto a plastic surface, eg. Small agar plate or microscope slide.
2. A small amount of cells were transferred from a well- isolated colony from the agar to mix with the solution.
Results
Positive: Explosive bubbling reaction should occur right immediately when the cells and solution were mixed.
Negative: No bubbling reaction.
Below is a picture showing the result of a positive and negative catalase test.
On the left shows a positive catalase test by having immediate explosive bubbling reaction.
On the right shows a negative catalase test by having no bubbling reaction.
Hello Jennifer,
ReplyDeleteIs catalase test useful only to differentiate between N. gonorrhoeae and other Neisseria species?
What is the significance of the test? What does it mean to observe a positive/negative result?
Hello Dr lee,
ReplyDeleteErm no. catalase test is also useful to differentiate many other types of bacteria just that in the lab i am working, catalase test is one of the confirmatory test to identify neisseria gonorrhoeae species so my post is more forcus on neisseria species.
And the significance of test is is that, catalase positve bacteria can produce catalase which is an enzyme that can break down hydrogen peroxide to oxygen and water. As peroxide is toxic to bacteria, catalase negative bacteria cannot survive in the presence of this chemical.
Positive result means catalase positive which is shown by the formation of bubble due to the formation of oxygen.
whereas, negative result means catalase neagtive.
rdgs.