Indole Broth (4mL)

Determine the indole production by members of the Enterobacteriaceae using Thermo Scientific™ Remel™ Indole Broth. Indole production is an important characteristic in the identification of many species of bacteria, specifically enteric gram-negative rods. Indole Broth is recommended by the American Public Health Association (APHA) and in the Identification of Enterobacteriaceae for use in the differentiation of enteric gram-negative rods^1,2.

Microorganisms that possess the enzyme tryptophanase have the ability to hydrolyze and deaminate tryptophan with the production of indole, pyruvic acid and ammonia³. Indole that splits from the tryptophan molecule on addition of the reagent ρ-dimethylaminobenzaldehyde results in a distinct red color that can be easily detected⁴.

• Ready to use - Liquid media
• Recommended by APHA in the Identification of Enterobacteriaceae for use in the differentiation of enteric gram-negative rods^1,2.
• Easy to interpret -
  • Positive test - Pink to red colored ring at the interface of the broth and the reagent
  • Negative test - No color development

Indole Broth contains casein peptone that supplies essential growth factors, trace elements, and is the source of tryptophan in this medium.. Sodium chloride maintains osmotic equilibrium. Certain gram-negative rods release indole after hydrolyzing tryptophan. After addition of dimethylaminobenzaldehyde, it combines with the indole and produces a distinct red color.