Diluents and test media · Indole test
Tryptone Water – tryptophan-rich broth for the indole test
Tryptone Water is a tryptophan-rich broth for the detection of indole production, an important test for the identification of E. coli and other Enterobacteriaceae, for example in the confirmation of thermotolerant coliforms.
- Indole test for E. coli confirmation
- Tryptone rich in tryptophan
- Simple, clear broth
How Tryptone Water works
Tryptone is a casein digest with a high tryptophan content. Bacteria with tryptophanase release indole, which is detected with Kovács reagent as a red ring at the surface of the broth.
Typical reactions
| Organism | Indole reaction |
| Escherichia coli | Indole positive – red ring |
| Klebsiella aerogenes | Indole negative – yellow ring |
Applications and practical notes
Diluents and simple peptone media are used to prepare samples and dilution series without harming the bacteria, and as base media for classic biochemical tests described for example in the FDA Bacteriological Analytical Manual. Typical applications include:
- Preparation of initial suspensions and dilution series
- Indole and other biochemical tests
- Rinsing and holding of samples
- Food, water and pharmaceutical laboratories
Working with Tryptone Water: Incubate at the temperature required by your method, for example 44 °C for thermotolerant E. coli, before adding the reagent.
Good practice with dehydrated media: keep the bottle tightly closed in a cool, dry place, weigh the powder quickly to avoid moisture uptake, and use fresh distilled or deionised water. Check the pH of each new batch after preparation and before use, and label prepared media with the date. Performance of each lot can be verified with reference strains according to ISO 11133, the standard for the preparation, production, storage and performance testing of culture media.
About general-purpose media: general-purpose media are not tied to one reference method. They are used in every laboratory for cultivation, revival of reference strains, purity checks and as bases for enriched and test media. Their performance is verified with reference strains according to ISO 11133, and media for susceptibility testing follow the requirements of EUCAST and CLSI. COLO.Science offers general media, enriched bases, supplements and QC strains from one source.
Complete sets from one supplier: COLO.Science supplies culture media, supplements, rapid tests, identification kits and QC strains as complete sets for the method you follow. Send us your sample types and standards, and we will prepare an offer with the matching products and documentation.
Tryptone Water is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include Tryptone Water, please send us a request. With every delivery of Tryptone Water you receive the lot number and expiry date, and on request we send the available documentation for Tryptone Water.
Where Tryptone Water fits in general microbiology
- Sample preparation – Peptone Water, Phosphate Buffer and other diluents
- Cultivation and revival – Nutrient, BHI and Columbia media
- Fastidious organisms – blood, chocolate and GC media with supplements
- Testing and identification – Mueller Hinton for susceptibility, CLED and chromogenic agar for urine, biochemical tests
See all general-purpose media in the Microbiology Catalogue →
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| Tryptone Water | PRO7551 | 500 g |
Product notice: preparation, storage conditions and shelf life are given on the label. Technical data on this page are for orientation; the label and the lot documentation apply. B2B prices are quoted net, excluding VAT.
Sales and technical support
COLO LabExperts
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Quotations and technical support for culture media and microbiology products across our international sales territory. B2B prices are net, excluding VAT.
COLO.SCIENCE | MICROBIOLOGY SUPPORT
Need the complete set for your method?
Send the sample type, target organism and the standard you follow. COLO.Science will put together the media, supplements, QC strains and confirmation tests for the whole procedure.
