Catalase Test
Microorganisms able to live in oxygenated environments produce enzymes which neutralize toxic forms of oxygen. One such enzyme is catalase, which breaks hydrogen peroxide into water and molecular oxygen. Organisms which produce catalase will bubble when placed into hydrogen peroxide. The catalase test is primarily used to distinguish among Gram-positive cocci: Member of the genus Staphylococcus are catalase-positive, and members of the genera Streptococcus and Enterococcus are catalase-negative.