Biochemical test · Tryptophan deaminase
TDA Reagent – tryptophan deaminase test
The TDA Reagent (3.4 % ferric chloride) detects tryptophan deaminase, for example in identification kits for Enterobacteriaceae.
- 3.4 % ferric chloride
- Red-brown = positive
- 10 mL
How TDA Reagent works
Tryptophan deaminase forms indolepyruvic acid, which reacts with ferric ions and gives a red-brown colour.
Typical results
| Result | Read-out |
| Positive (e.g. Proteus) | Reddish-brown |
| Negative | No colour change |
Technical data
| Storage | Room temperature, protected from light |
| Shelf life | 2 years |
Applications and practical notes
Biochemical reagents and stains are used for the confirmation of typical colonies in food, water, clinical and pharmaceutical microbiology. Typical applications include:
- Confirmation of typical colonies
- Biochemical identification of isolates
- Media preparation
- Teaching and reference laboratories
Working with TDA Reagent: Add 1 drop to the TDA well or tube after incubation and read immediately.
Good practice with media and supplements: 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 biochemical tests and stains: reference methods for food, water and pharmaceutical microbiology confirm typical colonies with a small set of classic tests – Gram stain, catalase, oxidase, indole, methyl red, Voges-Proskauer and others – before or alongside identification kits. Reliable reagents with known shelf life and a positive and negative control strain for each test are part of good laboratory practice according to ISO 11133. COLO.Science supplies the reagents together with media, identification kits and QC strains.
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.
TDA Reagent is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include TDA Reagent, please send us a request. With every delivery of TDA Reagent you receive the lot number and expiry date, and on request we send the available documentation for TDA Reagent.
Where TDA Reagent fits in microbiological testing
- Staining and microscopy – Gram stain and spore stain
- Rapid colony tests – catalase, oxidase and Lugol’s iodine
- Biochemical confirmation – indole, methyl red, Voges-Proskauer, nitrate, phenylalanine and tryptophan deaminase, ninhydrin, Nessler and Benedict reagents
- Media additives – glycerol, sterile liquid paraffin and TTC solution
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| TDA Reagent | PRO7663 | 10 mL |
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
Polje ob Sotli 4, SI-3255, Slovenia
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.
