Testing is the bread and butter of the scientific process. Our understanding of the sciences and the natural world would be incomplete without these vital, if sometimes mundane, processes and procedures.
Of course, how we test things, and the number of tests that we use in the scientific process, have as vastly changed as our understanding of science has.
It’s certainly ballooned in scope, that’s for sure!
There are hundreds of thousands, if not millions, of procedures that we carry out every day for even incredibly specific purposes. So many that it can be very frustrating to distinguish between them, and what exactly they are testing for.
In this article, we are going to discuss the catalase test, and what its purpose is in the field of chemistry and biochemistry.
We’re going to cover the uses it has, the several methods and procedures it uses, what the results of this test show us, as well as the importance of interpreting the results.
We’re also going to cover some of the precautions that you should be taken whilst you are out there performing this test.
The Purpose And Principle Of The Catalase Test
Before we go any further, we need to cover the principle and purpose of the catalase test. It pays to know what exactly you are testing for, after all!
To put it in simple terms, the catalase Test is a biochemical test that is done on aerobic organisms and lifeforms, the living tissue that uses oxygen in its vital processes.
More specifically, the test is detecting the production of the catalase enzyme that occurs in living tissue.
Catalase is an enzyme that is found in virtually all forms of life that interact with oxygen.
It helps break down the oxygen that is present in hydrogen peroxide, the chemical found in bleach that can be harmful to many organisms when exposed in large enough quantities and reverts them to their base hydrogen and oxygen atoms.
As you can imagine, this makes catalase an incredibly important enzyme to test for.
The catalase test specifically helps a tester or researcher to help distinguish between bacteria that do produce this vital enzyme and those that do not.
The process of separating hydrogen peroxide results in the creation of water molecules, and the release of oxygen atoms, which in liquid solutions, take the form of bubbles of oxygen.
Because of this result, measuring the results is relatively straightforward: Isolate a bacterium that you are looking to test, and see if bubbles form once hydrogen peroxide is introduced into the system.
What Are The Uses For The Catalase Test?
It is also important to consider why the catalase Test is useful for scientists and researchers.
Well, as we already mentioned, this test’s main use is to help differentiate between organisms, usually bacteria, that produce or don’t produce the catalase enzyme.
This is helpful for scientists that are looking to classify organisms that behave in specific ways, especially those that engage with the aerobic process in different ways.
Outside the field of scientific research, the catalase test is also helpful for tests in the field of medicine.
Mycobacterium tuberculosis, a highly infectious bacterial disease, is an organism that uses up vast amounts of oxygen in its processes, so produces a large amount of the oxygen bubble results that standard experiments of this test show.
Because of this, semi-quantitive uses of this test are useful for detecting the presence of tuberculosis in a given sample.
Finding the presence of this dangerous bacteria is certainly an incredibly useful tool in combatting this vital research to help combat its effects, so this test is vital in many biochemical studies around these bacteria.
Methods And Procedures Of The Catalase Test
The catalase test has several methods of applying it in a laboratory setting. The two most used procedures are the ‘Tube Method’ and the ‘Slide Method’.
Tube Method
A small amount of Hydrogen Peroxide (H2O2) is added to a solution contained in a test tube, hence the name. Generally speaking, this equates to about 2 to 3 drops, with a percentage of around 3-4%.
A sterile implement, usually some type of very thin rod made of cleaned/sterilized glass, plastic, or wood, will add a small colony of bacteria that are being tested to the hydrogen peroxide solution.
This colony of bacteria will have usually been isolated for around 24 hours, or one day, before the test is carried out, to avoid contamination. The minimum amount of time is around 18 hours.
The researcher/tester will then observe to see if bubbles are formed after the bacteria are added. The results should be easy to spot immediately after adding them.
Slide Method
In this testing method, the colony of bacteria that you are testing is added to a sterilized and dry glass microscope slide. The isolation time frame for the tube method also applies to this test.
Once the bacteria have been placed, the solution of hydrogen peroxide is then added to the slide.
Once the solution has been added, a microscope is used to detect if small oxygen bubbles have started to form.
As we mentioned before, there are other methods of carrying out this test.
However, these two methods are generally the easiest to carry out by researchers, as they only require a small amount of solution and bacteria colony to test for, which makes it possible to carry out this test virtually anywhere.
Interpreting The Results Of The Catalase Test
The results of this test are usually quite easy to interpret. As we mentioned earlier in this article, the key detail that an observer is looking for is the presence and formation of bubbles in the solution.
A strong reaction would be is a relatively large amount of bubbles are formed once the solution and bacteria colony are combined.
Results such as this will usually demonstrate the presence of bacteria such as staphylococci and mycobacterium tuberculosis, organisms that are very intensely aerobic.
A weak reaction to this test will usually result in a small number of bubbles being released into the solution. This would indicate that catalase is being produced, but not at a large or fast rate.
A negative result to this test, the presence of no catalase, would be shown by a total lack of any bubble formation, even after an extensive period, over 20 to 30 seconds in this case.
Bacteria such as streptococci or enterococci are examples of bacteria that will likely produce this result.
Precautions When Carrying Out This Test
The bacteria that you use in your test should not be taken from a blood agar culture. Red blood cells already carry a certain amount of catalase in them, meaning that your tests on your bacteria colony will be null and void.
Isolation of your bacteria colonies is important, but make sure that you test them within around 24 hours, otherwise you may get a false negative result.
Final Thoughts
As you can see, the catalase test is a surprisingly straightforward test to carry out. And hopefully, this article has helped you understand the scientific process a little better.
Ever since I was a little girl, I have been fascinated by science. Every holiday I would ask for the newest science kit, and spend weeks learning with it.
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