Indole Broth 4mL Tube, 10/Pk

Indole Broth (often referred to as Tryptone Water) is a biochemical test medium used to determine the ability of an organism to split indole from the amino acid tryptophan. Each tube contains 4mL of a broth rich in tryptophan-containing peptones. This test is a critical component of the IMViC series (Indole, Methyl Red, Voges-Proskauer, Citrate) used to differentiate members of the Enterobacteriaceae family.

The medium tests for the presence of the enzyme tryptophanase. When an organism possessing this enzyme (such as E. coli) is incubated in the broth, it hydrolyzes the tryptophan to produce indole, pyruvic acid, and ammonia.

Because indole is not visible on its own, a reagent must be added after incubation. Upon adding a few drops of Kovac’s Reagent (or Ehrlich’s Reagent) to the 4mL culture, a chemical reaction occurs with any indole present.

• Positive Result: A distinct red ring forms at the liquid-air interface (indicating E. coli or Proteus vulgaris).

• Negative Result: The reagent layer remains yellow or brown (indicating Klebsiella or Enterobacter).

• Biochemical ID: Tests for tryptophanase enzyme activity.

• IMViC Component: The "I" in the standard coliform differentiation battery.

• Differentiation: Separates E. coli (+) from Klebsiella/Enterobacter (-).

• High Tryptophan: Formulated with high-quality tryptone to ensure ample substrate.

• Clear Readout: Requires Kovac's Reagent (sold separately) to visualize the red ring.

• Format: Sterile 4mL tubes in a 10-pack, optimized for single-test use.

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