Catalase and cytochrome c oxidase are two important enzymes, which in combination with other tests, are used for typing (species or subspecies identification) of bacteria. Oxidase is often used as a sloppy word, when cytochrome c oxidase is meant.
Catalase + (Cat +) means that the bacterium has catalase, which converts hydrogene peroxid to oxygen and water. This reaction is utilized in the katalas-testet. Most aerobic and fakultatively anaerobic bacteria have catalase.
Oxidase + (Ox +) means that the bacterium has cytochrome c oxidase as terminal enzyme in the respiratory chain. This enzyme catalyze conversion of oxygen to water in the presence of cytochrome c and protons. Many aerobic bacteria have this enzyme, which can be utilized in the oxidas-testet.
V instead of + or -, means that certain strains of the bacteria have the enzyme, whereas other strains of the same bacterial species lack the enzyme. If the majority of the strains have the enzymes, it can be indicated by (+) and if the majority of the strains lack the enzymes, it can be indicated by (-).