Salmonella detection · Step 3 – selective isolation
MLCB Agar – isolation of Salmonella including lactose-positive strains
Mannitol Lysine Crystal Violet Brilliant Green (MLCB) Agar is a selective medium for the isolation of Salmonella. It also detects lactose-fermenting and H₂S-producing strains that can be missed on lactose-based agars, so it is useful as a second plating agar.
- Salmonella: light purple colonies with black centres
- Detects lactose-positive Salmonella strains
- Dehydrated powder, 500 g bottle · COLO code PRO7558
How MLCB Agar works
Crystal violet and brilliant green inhibit Gram-positive bacteria and many coliforms. Mannitol is fermented by Salmonella, while lysine decarboxylation keeps the medium alkaline, and thiosulfate with iron salts shows hydrogen sulfide as black colony centres. Lactose is not part of the differentiation, so lactose-positive Salmonella are not missed.
Typical colony appearance
| Organism | Colonies |
| Salmonella | light purple, with black centres |
Technical data
| Preparation | 49.0 g per litre of water; heat to boiling until dissolved, avoid overheating; cool to about 50 °C and pour plates |
| Final pH | 6.8 ± 0.2 |
| Incubation | 36 ± 1 °C, 18–24 h |
| Storage | Dry, dark place; close the cap tightly after use |
| Shelf life | 3 years unopened |
Applications and practical notes
MLCB Agar is used as a second plating medium for Salmonella, especially where lactose-positive strains are expected. Typical applications include:
- meat, poultry, eggs and egg products
- milk, dairy products and infant formula
- feed, spices and dry foods
- environmental swabs from the food production area
Working with MLCB Agar: MLCB Agar is a good second agar next to XLD, because its differentiation does not depend on lactose. Typical colonies are confirmed biochemically and serologically.
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.
MLCB Agar is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include MLCB Agar, please send us a request.
Where MLCB Agar fits in the Salmonella workflow
- Pre-enrichment – Buffered Peptone Water or Lactose Broth
- Selective enrichment – RVS Broth and MKTTn Broth
- Selective isolation – XLD Agar plus a second selective or chromogenic agar
- Confirmation – TSI, Lysine Iron Agar, Urea Agar, latex and biochemical identification
See the complete Salmonella set in the Microbiology Catalogue →
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| MLCB Agar, dehydrated | PRO7558 | 500 g |
| XLD Agar, dehydrated | PRO7437 | 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
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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.
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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.
