Coliforms and E. coli · Count with fluorescence
Violet Red Bile Agar with MUG – coliforms and E. coli on one plate
Violet Red Bile Agar with MUG combines the coliform colony count with a fluorogenic test for E. coli. Colonies of E. coli fluoresce blue under UV light at 366 nm.
- Coliforms: purple-red colonies
- E. coli: additional blue fluorescence
- No autoclaving
How Violet Red Bile Agar with MUG works
The VRBA base selects lactose-fermenting Gram-negative bacteria. β-glucuronidase of E. coli releases a fluorescent product from MUG, so E. coli colonies can be counted separately under UV light.
Typical colony appearance
| Organism | Colonies |
| E. coli | Purple-red colonies with precipitate and blue fluorescence |
| Other coliforms | Purple-red colonies, no fluorescence |
Technical data
| Preparation | 41.6 g/L; boil to dissolve, no autoclaving |
| Final pH | 7.4 ± 0.2 |
| Incubation | 35-37°C, 18-24 h |
| Storage | Dry, dark place; keep the container tightly closed |
| Shelf life | 3 years unopened |
Applications and practical notes
Plate count and isolation media for coliforms and E. coli are used in food, feed, water and hygiene testing, for example according to ISO 4832 and ISO 16649-2. Typical applications include:
- Coliform and E. coli colony counts in food and feed
- Isolation of lactose-fermenting Gram-negative bacteria
- Process hygiene criteria in dairy, meat and vegetable production
- Teaching and routine quality-control laboratories
Working with Violet Red Bile Agar with MUG: Examine plates under a 366 nm UV lamp in a darkened room and mark fluorescent colonies before counting.
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 coliform and E. coli methods: coliforms and E. coli are counted either by the multiple-tube (MPN) method, with a presumptive broth followed by confirmation broths, or by colony counts on selective agars. FDA BAM Chapter 4 describes both approaches for food and water, and ISO 16649-2 gives the colony-count method for β-glucuronidase-positive E. coli on TBX Agar. E. coli O157 and other STEC need dedicated media, serology and PCR. COLO.Science offers media, supplements, rapid tests, identification kits and QC strains for every step.
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.
Violet Red Bile Agar with MUG is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include Violet Red Bile Agar with MUG, please send us a request. With every delivery of Violet Red Bile Agar with MUG you receive the lot number and expiry date, and on request we send the available documentation for Violet Red Bile Agar with MUG.
Where Violet Red Bile Agar with MUG fits in coliform and E. coli testing
- Presumptive test – Lauryl Sulfate Tryptose Broth (MPN) or VRBL / chromogenic agar (colony count)
- Confirmation – BGLB Broth for coliforms; EC or EC-MUG Broth at 44.5 °C for E. coli
- Isolation – EMB, MacConkey, TBX or chromogenic E. coli agar
- Identification – IMViC kit; for O157 and STEC: SMAC or chromogenic O157 agar, latex and PCR
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| Violet Red Bile Agar with MUG (VRBA-MUG) | PRO7504 | 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
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.
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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.
