Indole Test : Indole test is used to determine the ability of an organism to split
amino acid tryptophan to form the compound indole. Tryptophan is hydrolysed by
tryptophanase to produce three possible end products – one of which is indole. Indole
production is detected by Kovac’s or Ehrlich’s reagent which contains 4 (p)-dimethylamino
benzaldehyde, this reacts with indole to produce a red coloured compound. Indole test is a
commonly used biochemical test