The catalase test tests for the presence of catalase, an enzyme that breaks down the harmful substance hydrogen peroxide into water and oxygen. If an organism can produce catalase, it will produce bubbles of oxygen when hydrogen peroxide is added to it Purpose of Catalase Test The morphologically similar Enterococcusor Streptococcus (catalase negative) and Staphylococcus (catalase positive) can be differentiated using the catalase test. Also valuable in differentiating aerobic and obligate anaer