Listeria detection · Step 3 – selective isolation
PALCAM Agar – selective agar for Listeria
PALCAM Agar is a highly selective and differential plating medium for Listeria monocytogenes and other Listeria species. It is widely used as the second plating agar next to the chromogenic Ottaviani-Agosti type medium. The base is completed with PALCAM Agar Supplement.
- Listeria: grey-green colonies with black sunken centre and black halo
- Second plating agar for Listeria
- Dehydrated powder, 500 g bottle · COLO code PRO7470
How PALCAM Agar works
Lithium chloride, polymyxin B, acriflavine and ceftazidime suppress most accompanying bacteria. Listeria hydrolyses aesculin, which gives a black zone with ferric ions, and does not ferment mannitol, so its colonies stay grey-green while mannitol fermenters turn the phenol red indicator yellow.
Typical colony appearance
| Organism | Colonies |
| Listeria | grey-green, with black sunken centre and black halo |
| Mannitol fermenters | yellow colonies with yellow zone |
Technical data
| Preparation | 73.9 g per litre of water; boil to dissolve, sterilise at 121 °C for 15 min, cool to 50 °C and add 1 vial of PALCAM supplement per 100 mL |
| Final pH | 7.2 ± 0.2 |
| Incubation | 35–37 °C, 24 h |
| Storage | Dry, dark place; close the cap tightly after use |
| Shelf life | 3 years unopened |
Applications and practical notes
PALCAM Agar is commonly used as the second plating medium for Listeria next to the Ottaviani-Agosti type agar in ISO 11290-1. 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 PALCAM Agar: Add the supplement only to the cooled base and incubate the plates inverted, if needed under microaerobic conditions as described in the method. Read the plates after 24 h and again after 48 h.
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.
PALCAM 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 PALCAM Agar, please send us a request. With every delivery of PALCAM Agar you receive the lot number and expiry date, and on request we send the available documentation for PALCAM Agar.
Where PALCAM Agar fits in the Listeria workflow
- Primary enrichment – Half-Fraser Broth
- Secondary enrichment – Fraser Broth
- Selective isolation – chromogenic Listeria agar (Ottaviani-Agosti type) plus PALCAM or Oxford Agar
- Confirmation – subculture on TSYEA, biochemical identification and latex
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| PALCAM Agar Base, dehydrated | PRO7470 | 500 g |
| PALCAM Agar Supplement | PRO7678 | 10 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
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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.
