Catalase Biochemical Test

Catalase Biochemical Test

Introduction

Catalase is a name of a enzyme.This enzyme is nearly present in all living plants and animals which are always exposed to oxygen.Catalase enzyme is also present in aerobic and facultative anaerobic micro-organisms.Generally this micro-organisms utilise oxygen and produce hydrogen peroxide and this hydrogen peroxide is toxic to the cells and it effects the cells enzyme system so to avoid this toxic effect micro-organism produces catalase enzyme. The role of catalase enzyme is to convert hydrogen peroxide molecule to water and oxygen and this reaction is a irreversible reaction.

2H2O2   is converted to     2H2O + O2

It is also one of the reason that anaerobic micro-organisms do not survive in presence of oxygen as hydrogen peroxide is produced and due to lack of catalase enzyme this hydrogen peroxide destroy cells enzyme system and the cell dies.

Why is it important to carry out Catalase test ?

The purpose of carrying out a catalase test is to detect production of catalase enzyme by bacteria. Secondly catalase test help us to determine whether the micro-organisms are aerobic,anaerobic or obligate anaerobic in nature and due to this we can differentiate the organisms in catalase positive or catalase negative group. This differentiation helps us in identification and classification of bacteria.

How is the Catalase test performed ?

The Catalase test can be performed by using two methods.

  1.  Test tube method.
  2. Slide method.

1.Test tube method.

In test tube method the catalase test is performed in sterile test tube.

Aim

The aim of the experiment is to carry out catalase test by tube method.

Requirement

  1. Bacterial culture
  2. Sterile test tube.
  3. Dropper.
  4. Wireloop.
  5. Hydrogen peroxide.

Procedure

  1. A sterile test tube is taken and with the help of a dropper 5 to 6 drops of hydrogen peroxide are added in the all this procedure is carried out under sterile conditions.
  2. Further with the help of a sterile nichrome wireloop a colony of a test culture is picked up and inserted in hydrogen peroxide containing test tube.
  3. The test tube is observed for production of effervescence that is bubble formation this reaction occurs immediately after addition of culture.

Observation

 Positive catalase-test
Positive catalase-test
neg-catalese-test
Negative catalase test

 Conclusion

If effervescence is observed, test culture is catalase positive and if their are no effervescence test culture shows negative catalase test.

2. Slide method

Aim

The aim of the experiment is to carry out Catalase test by Slide method.

Requirement

  1. Bacterial culture.
  2. Clean grease free slide.
  3. Wireloop
  4. Hydrogen peroxide.

Procedure

  1. Take a clean grease free slide and on it take a drop of sterile water and with the help of a sterile nichrome wireloop pick a colony of a test culture.
  2. Further with the with the help of a dropper add 3 to 4 drops of hydrogen peroxide all this procedure should be carried in sterile condition.
  3. After addition of hydrogen peroxide the slide is observed for formation of effervescence that is bubbles.

Conclusion

If effervescence are observed within 20 second then catalase test is positive and if effervescence are not observed then catalase test is negative.

List of some Catalase positive micro-organism.

  • Pseudomonas aeruginos
  • Mycobacterium tubercule
  • Nisseria gonorrhea
  • Helicobacter pylori
  • Candida
  • Staphylococcus aureus
  • E.coli

One Comment

  1. stainlexdelsu January 28, 2016 Reply

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