TRYPTONE BROTH (TRYPTONE WATER)

Description

Tryptone Water is recommended by APHA for detection of indole production by coliforms, which is a key feature in differentiation of bacteria. A slight modification of Tryptone Water is recommended by ISO committee for the same purpose. This test demonstrates the ability of certain bacteria to decompose the amino acid tryptophan to indole which accumulates in the medium. Tryptone Water is used in conjunction with Brilliant Green Bile Broth 2% to determine the most probable number (MPN) of E.coli in food sample. Growth and gas production and indole production in Tryptone Water following incubation of both media at 44 ? 1?C is used as the basis for the presumptive E.coli test. For determination of indole, inoculate the medium with inoculum of an 18-24 hours pure culture. Incubate the tubes at 35 ? 2?C for 18-24 hours. Add 0.5 ml of indole reagent directly to the tube and agitate. Allow the tubes to stand for 5-10 minutes. Formation of red ring at the top of the tube indicates indole production. Indole testing is recommended as an aid in the differentiation of microorganisms based on indole production. For complete identification of the organisms, further biochemical confirmation is necessary.