Catalase Test

Catalase Test

Catalase Test is a biochemical test. This test is used to differentiate these bacteria that produce the enzyme catalase, such as staphylococci from non-catalase Producing bacteria such as streptococci.

Also valuable in differentiating aerobic and obligate anaerobic bacteria. It is also used to differentiate clostridium, which is catalase negative, from bacillus species which are catalase Positive.

Catalase test can be used in the identification of Enterobacteriaceae.

Principle:

Catalase mediates the breakdown of hydrogen Peroxide (H₂O₂) into oxygen and writer. To find out if a particular bacterial isolate can produce catalase enzyme, a small inoculum of a bacterial is late mixed into a 3% H₂O₂ solution. It is observed for the rapid elaboration of oxygen bubbles. The lack of catalase is evident by a lack of double production.

Catalase:

Types of Catalase:

1-Aerobic Metabolism:

Bacteria that conduct aerobic metabolism (biological reaction) require Or Produce H₂O2 as a toxic Product of their metabolism.

Cause:

Toxic H₂O₂ can cause intracellular damage such as damage to DNA, Lipid, and proteins. To remove H₂O2 and other similar compounds, cells Produce catalase enzyme to break down H₂O₂ into liquid water (H₂O) and oxygen (Or) 2H₂O₂ Catalase 2H₂O + O₂.

2- Anaerobic Metabolism:

Anaerobic micro-organisms do not survive in the Presence of oxygen as H₂O₂ is produced and due to lack of catalase enzyme this H₂O₂ destroys the cell enzyme system and the cell dies.

How to Perform Catalase Test in Lab:

There are two methods of the Catalase test:

• Test tube Method:
• Slide Method:

1- Test Tube Method:

In the test tube method, the catalase test is Performed in a sterile test tube:

Requirements:

• Bacterial culture
• Sterile Test tube
• Dropper
• Wire Loop
• 3% H₂O₂ (Hydrogen Peroxide)

Tube method:

• 3./. H2O2
• Catalase Negative
• no (bubble)

• 3% H2O2
• Catalase Positive
• (Bubble Present)

Procedure:

1. Add 1-2 ml of H2O2 solution into a test tube.
2. Further, with the help of a sterile niche wine loop, a colony of a test culture is Picked 2 up and inserted in H2O2 containing test tube.
3. Observe for immediate bubbles.

Slide Test Method:

In a slide Method, the catalase test is performed in a clean grease free slide:

Requirements:

• Bacterial culture.
• Clean Grease-free slide.
• Wire Loop, sterile wooden stick.
• 3% H₂O₂ (Hydrogen peroxide).

Procedure:

1. Use a nichrome wire loop to transfer a small amount of colony growth to the surface of a glass slide.
2. Place a 2-3 drop of 3% H₂O₂ in the glass slide.
3. After the addition of H₂O_2, the slide is observed for the formation of oxygen bubbles.

Precautions:

• The test organisms should not be taken from blood agar culture 2 red blood cell contains catalase.
• Culture should be 18-24 hours old Iron wide loop should not be used.

Result Interpretation:

NOTE:

Care must be taken when testing an organism cultured on a medium containing blood because catalase is Present in red cells.

Caution:

Performing the test on the slide is not recommended because of the risk of contamination from active bubbling. When the rapid slide technique is used, the hydrogen peroxide solution should be added to the organism. Suspension after placing the slide in a Petri dish. The dish should be covered immediately, and the preparation observed for bubbling through the lid.