Listeria detection · enrichment (FDA method)
Buffered Listeria Enrichment Broth – enrichment for Listeria monocytogenes
Buffered Listeria Enrichment Broth (BLEB) is the enrichment broth for Listeria monocytogenes in the FDA Bacteriological Analytical Manual. The buffered base keeps the pH stable, and the selective agents are added as a supplement after the first hours of incubation.
- Enrichment broth of the FDA Listeria method
- Phosphate-buffered base for stable pH
- Dehydrated powder, 500 g bottle · COLO code PRO7532
How Buffered Listeria Enrichment Broth works
The nutrient-rich, buffered base supports the recovery of injured Listeria. The BLEB supplement adds nalidixic acid, acriflavine and an antifungal agent that suppress the accompanying bacteria and moulds.
Technical data
| Preparation | 47.0 g per litre of water; boil to dissolve, sterilise at 121 °C for 15 min, cool and add one set of BLEB supplement (A + B) per 500 mL |
| Final pH | 7.3 ± 0.2 |
| Incubation | 30 ± 1 °C, 48 h |
| Storage | Powder dry and dark; supplements 2–8 °C |
| Shelf life | 3 years unopened |
Applications and practical notes
Buffered Listeria Enrichment Broth is the enrichment broth in FDA BAM Chapter 10. Typical applications include:
- ready-to-eat foods, cooked meat products and delicatessen
- milk, cheese and other dairy products
- fish, seafood and smoked fish
- environmental swabs from food production areas
Working with Buffered Listeria Enrichment Broth: Follow the timing of the method for adding the selective supplement, which is usually added after the first hours of incubation. Keep the supplements refrigerated until use.
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 the Salmonella culture method: the reference method for Salmonella in the food chain, ISO 6579-1, has four steps: non-selective pre-enrichment, selective enrichment in two broths, plating on two selective agars and confirmation of typical colonies. The FDA BAM Chapter 5 follows the same principle with media adapted to different food types. Rapid tests and identification kits shorten the time to result, but positive screening results are usually confirmed by the culture method. COLO.Science offers products for every step, so that one supplier covers the whole procedure.
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.
Buffered Listeria Enrichment Broth is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include Buffered Listeria Enrichment Broth, please send us a request. With every delivery of Buffered Listeria Enrichment Broth you receive the lot number and expiry date, and on request we send the available documentation for Buffered Listeria Enrichment Broth.
Where Buffered Listeria Enrichment Broth fits in the workflow
- Enrichment – Buffered Listeria Enrichment Broth with BLEB supplement
- Selective isolation – chromogenic Listeria agar plus PALCAM or Oxford Agar
- Purification – subculture on TSYEA
- Confirmation – biochemical identification and latex
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| Buffered Listeria Enrichment Broth Base | PRO7532 | 500 g |
| BLEB Supplement | PRO7728 | 2 × 5 vials |
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.
