What is the purpose of the oxidase test?

In microbiology, the oxidase test is a simple test performed to determine if a bacterial strain can produce the enzyme cytochrome oxidase. This enzyme is an important enzyme in the electron transport chain.

If bacteria have a positive oxidase test, then they do produce the enzyme cytochrome oxidase. Thus, the bacteria also derives its energy from an electron transport chain. Cytochrome oxidase is a key enzyme within the electron transport chain and catalyzes the reaction that transfers electrons from NADH to any electron acceptors. In general, bacteria electron acceptors are typically the element oxygen. If the test is negative, then the bacteria does not have an electron transport chain within its cells.