Which test is used to detect the presence of cytochrome C oxidase?

The test used to detect the presence of cytochrome C oxidase is the oxidase test. This test is based on the ability of certain bacteria to utilize cytochrome C as part of their electron transport chain in respiration. When the bacteria are incubated with a reagent that serves as an electron donor in the oxidase test, a color change indicates the presence of cytochrome C oxidase. This is typically visualized as a color change to purple within a few seconds, confirming the activity of the enzyme.

The other tests mentioned assess different factors or metabolic pathways in bacteria: the catalase test determines the presence of catalase, which breaks down hydrogen peroxide; the nitrate reduction test evaluates the ability of bacteria to reduce nitrate; and the viable plate count is a method for determining the number of live cells in a sample based on colony formation. Each of these tests serves a unique purpose that does not relate directly to cytochrome C oxidase detection.