Bacillus cereus · Plate count · granulated
Mannitol Egg Yolk Polymyxin Agar Base – granulated MYP
The granulated Mannitol Egg Yolk Polymyxin Agar Base is used for the count of presumptive Bacillus cereus in foods. Granules produce less dust when weighing and dissolve evenly.
- Granulated – less dust, better flow
- For Bacillus cereus counts
- Complete with polymyxin B and egg yolk
How Mannitol Egg Yolk Polymyxin Agar Base works
Mannitol, egg yolk and polymyxin B make the medium selective and differential. B. cereus does not ferment mannitol, so its colonies stay pink, and its lecithinase breaks down egg-yolk lecithin, forming a white precipitate around the colonies. Polymyxin B suppresses Gram-negative bacteria.
Typical colony appearance
| Organism | Colonies |
| Bacillus cereus | Pink colonies with a large precipitate zone |
| Bacillus subtilis | Yellow colonies, no zone |
| Escherichia coli | Inhibited |
Technical data
| Preparation | 46 g in 950 mL; boil to dissolve, autoclave 121 °C 15 min, cool to about 50 °C; per 95 mL add one vial of Polymyxin B Supplement for MYP Agar and 5 mL of Egg Yolk Emulsion 50 % |
| Final pH | 7.3 ± 0.1 |
| Incubation | 30 ± 2 °C, 24–48 h |
| Storage | Dry, dark place; keep the container tightly closed |
| Shelf life | 3 years unopened |
Applications and practical notes
Bacillus cereus forms heat-resistant spores and toxins and is counted in rice, starchy foods, dairy products, spices and ready meals according to ISO 7932 and the FDA BAM Chapter 14. Typical applications include:
- Cooked rice, pasta and starchy foods
- Milk powders, dairy products and infant foods
- Spices, herbs and dried ingredients
- Ready meals and catering samples
Working with Mannitol Egg Yolk Polymyxin Agar Base: Weigh the granules without grinding them and keep the bottle closed between uses, because granules also absorb moisture.
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 Bacillus cereus method: presumptive Bacillus cereus is counted according to ISO 7932 on Mannitol Egg Yolk Polymyxin (MYP) Agar: typical colonies are pink (mannitol not fermented) and surrounded by a precipitate of hydrolysed lecithin. Selected colonies are confirmed by haemolysis on blood agar. The FDA BAM Chapter 14 adds tests that separate B. cereus from B. thuringiensis by its toxin crystals. COLO.Science offers media, supplements, identification kits and QC strains for 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.
Mannitol Egg Yolk Polymyxin Agar Base is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include Mannitol Egg Yolk Polymyxin Agar Base, please send us a request. With every delivery of Mannitol Egg Yolk Polymyxin Agar Base you receive the lot number and expiry date, and on request we send the available documentation for Mannitol Egg Yolk Polymyxin Agar Base.
Where Mannitol Egg Yolk Polymyxin Agar Base fits in Bacillus cereus testing
- Sample preparation – dilution in Buffered Peptone Water or peptone saline
- Plate count – MYP Agar with polymyxin B and egg yolk, 30 °C, 18–48 h
- Alternative isolation – Chromogenic Bacillus cereus Agar or Bacillus cereus Count Plate
- Confirmation – haemolysis, biochemical identification, protein crystal stain; QC strains for each run
See all Bacillus cereus products in the Microbiology Catalogue →
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| Mannitol Egg Yolk Polymyxin Agar Base, granulated | PRO7636 | 250 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.
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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.
