The catalase test is a test for the presence of the catalase enzyme. Most organisms posess this enzyme capable of breaking down hydrogen peroxide. Organisms containing the catalase enzyme will form oxygen bubbles when exposed to hydrogen peroxide.
Tips for Success: Do not use a nichrome loop as this will give a false-positive reaction. Because hydrogen peroxide is unstable, always check the expiration date on the solution. Do not perform the catalase test on blood agar, because blood cells in the agar contain the catalase enzyme. Always run positive and negative controls from known cultures.
Place a drop of 3% hydrogen peroxide onto a clean microscope slide.
Touch an isolated colony with an inoculating loop
Place the loop, carrying some of the isolate, into the drop of hydrogen peroxide.
Observe the slide for the evolution of bubbles
The reaction is positive if oxygen bubbles form rapidly.