Catalase test

The catalase test is used to detect the presence of catalase enzyme by the decomposition of hydrogen peroxide to release oxygen and water as shown by the following reaction:

2 H2O2 → 2H2O + O2

The catalase reaction is evident by the rapid formation of bubbles. Hydrogen peroxide is formed by some bacteria as an oxidative end product of the aerobic breakdown of sugars. If allowed to accumulate, it is highly toxic to bacteria and can result in cell death. Catalase either decomposes hydrogen peroxide or oxidises secondary substrates, but it has no effect on other peroxides.

There are method variations of the catalase test and these include the slide test method, the tube or bottle method and the agar slant method. However, the commonly used methods in microbiology laboratories are the tube or bottle method and the agar slant method because it limits catalase aerosols, which have been shown to carry viable bacterial cells, that if inhaled could cause infections as well as contamination in other laboratory work being set up and work surface areas.

Public Health England has opened a consultation on the standard test method. For details see: UK Government Gateway: https://www.gov.uk/government/consultations/uk-smi-tp-8-catalase-test

Posted by Dr. Tim Sandle