Indole Test- Principle, Media, Procedure, Types, Results, Uses


Indole test is a biochemical test that determines whether a bacterial species can produce indole from the amino acid tryptophan. Indole is a nitrogen-containing compound that is formed by the action of an enzyme called tryptophanase, which breaks down tryptophan into indole, pyruvic acid, ammonia, and energy. Indole can be detected by adding a chemical reagent that reacts with it to produce a color change. The indole test is one of the four tests in the IMViC series, which is used to differentiate members of the Enterobacteriaceae family. The indole test is also useful for identifying other bacteria that can produce indole, such as Proteus, Morganella, and some anaerobes. The indole test can be performed in different ways, such as the spot test, the tube test, or the Ehrlich`s reagent test, depending on the type of medium and reagent used. The indole test is a simple and rapid method to characterize bacteria based on their metabolic capabilities.