This test is used to identify organisms that produce the enzyme, catalase. This enzyme detoxifies hydrogen peroxide by breaking it down into water and oxygen gas.
The bubbles resulting from production of oxygen gas clearly indicate a catalase positive result. The sample on the right below is catalase positive. The Staphylococcus spp. and the Micrococcus spp. are catalase positive. The Streptococcus and Enterococcus spp. are catalase negative.