Test for Catalase

Test for Catalase

Aim

To test whether the given culture is catalase positive by the catalase test

Theory and Principle

Catalase test demonstrates the presence of catalase, an enzyme that catalyses the release of oxygen from hydrogen peroxide (H₂O₂). It is used to differentiate those bacteria that produces an enzyme catalase, such as staphylococci, from non-catalase producing bacteria such as streptococci.

The enzyme catalase mediates the breakdown of hydrogen peroxide into oxygen and water. The presence of the 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.

Requirements

• Slides

• Nichrome loop or toothpick

• 24hour old culture

• 3%hydrogen peroxide

• Dropper

Procedure

Slide Method

1. Use a loop or sterile wooden stick to transfer a small amount of colony growth in the surface of a clean, dry glass slide.

2. Place a drop of 3% H₂O₂ in the glass slide.

3. Observe for the evolution of oxygen bubbles.

Diagram

Observation (any one to be reported depending on the culture)

Positive: Copious bubbles produced, active bubbling

Examples: Staphylococci, E. coli, Enterobacter, Klebsiella, Shigella, Yersinia, Pseudomonas.

Negative: No or very few bubbles produced.

Examples: Streptococcus and Enterococcus sps.

Result

The given culture was found to be catalase positive as determined by the catalase slide test.