CATALASE TEST
AIM
To test the Catalase enzyme
producing efficiency of Bacteria.
PRINCIPLE
Catalase test is used to
differentiate the bacteria that produce an enzyme Catalase, such as Staphylococcus
sp. from Non-catalase producing bacteria such as Streptococcus sp.
It is also used for differentiating Bacillus sp. from Clostridium
sp. In 1893, a publication by Gottstein brought attention to bacterial
catalase, making it one of the first bacterial enzymes.
Aerobic and facultative anaerobic
organisms produce two toxins during normal metabolism. One is Hydrogen peroxide
(H2O2) and another one is Superoxide radical (O2−). These
bacteria have two enzymes that detoxify the products of normal metabolism. One
of these enzymes, Catalase, is capable of converting Hydrogen peroxide to Water
and Oxygen. Normally, 5 % H2O2 is used for the detection
of Catalase in bacteria. The presence of the Catalase enzyme in a bacterial
isolate is evident when a small inoculum is introduced into hydrogen peroxide,
and the rapid elaboration of oxygen bubbles occurs. The lack of Catalase is
evident by a lack of or weak bubble production. The culture should not be more
than 24 hours old.
Catalase positive bacteria include
Strict aerobes as well as Facultative anaerobes, although they all have the
ability to respire using oxygen as a terminal electron acceptor. Catalase
negative bacteria may be Anaerobes, or they may be Facultative anaerobes that
only ferment and do not respire using oxygen as a terminal electron acceptor (Streptococcus
sp.).
MATERIALS REQUIRED
- Test bacteria
- 3 % Hydrogen peroxide (H2O2)
- Glass slide or Test tube
- Sterile Wooden stick or Glass rod
PROCEDURE
I) Tube Catalase Test
a) Pour 1 - 2 ml of 3 % Hydrogen peroxide (H2O2)
solution into a test tube.
b) Using a sterile wooden stick or a glass rod, take several
colonies of the 18 to 24 hours test organism and immerse in the 5 % Hydrogen
peroxide (H2O2) solution.
c) Observe for immediate bubbling.
II) Slide Catalase Test
a) Use a sterile wooden stick or glass rod to transfer a
small amount of colony growth in the surface of a clean, dry glass slide.
b) Place a drop of 5 % Hydrogen peroxide (H2O2) in
the glass slide.
c) Observe for the evolution of oxygen bubbles.
OBSERVATION AND RESULTS
· Catalase Positive Test – Immediate bubble formation
·
Catalase
Negative Test – No bubble formation
Figure – 1: Catalase test (Slide test and Tube test) (Source: microbiologyinfo.com)
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