Bacillus cereus · Supplement
Egg Yolk Emulsion – 50 % emulsion for MYP and egg yolk agars
Egg Yolk Emulsion 50 % is a sterile emulsion of egg yolk in saline for MYP Agar and other egg yolk media. It shows the lecithinase reaction of Bacillus cereus and clostridia.
- Sterile 50 % egg yolk emulsion
- 5 mL per 95 mL of MYP base
- Small pack: 5 × 5 mL
How Egg Yolk Emulsion works
Egg yolk contains lecithin and lipoproteins. Bacteria with lecithinase, such as Bacillus cereus and Clostridium perfringens, break them down and form an opaque precipitate zone around their colonies, which is a key reading in the reference methods.
Technical data
| Composition | 50 % egg yolk in sterile saline |
| Use | 5 mL per 95 mL of MYP base, added at about 50 °C |
| Storage | 2–8 °C |
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 Egg Yolk Emulsion: Warm the emulsion to room temperature and mix gently before adding it to the base at about 50 °C.
Good practice with media and supplements: 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.
Egg Yolk Emulsion is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include Egg Yolk Emulsion, please send us a request. With every delivery of Egg Yolk Emulsion you receive the lot number and expiry date, and on request we send the available documentation for Egg Yolk Emulsion.
Where Egg Yolk Emulsion 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 |
|---|---|---|
| Egg Yolk Emulsion 50 % | PRO7743 | 5 × 5 mL |
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.
