Bacillus cereus · Chromogenic isolation
Chromogenic Bacillus cereus Agar – blue-green colonies with white halo
Chromogenic Bacillus cereus Agar is a selective chromogenic medium for the isolation and count of Bacillus cereus. Typical colonies are green to blue-green, rough and surrounded by a white halo, which makes reading easier than on MYP.
- Blue-green colonies with white halo
- Easy reading of mixed flora
- Complete with the chromogenic supplement
How Chromogenic Bacillus cereus Agar works
A chromogenic substrate is cleaved by an enzyme of B. cereus and colours the colonies blue-green, while hydrolysis of a lipid substrate forms a white halo. Selective agents in the supplement inhibit Gram-negative bacteria and yeasts.
Typical colony appearance
| Organism | Colonies |
| Bacillus cereus | Green to blue-green rough colonies with white halo |
| Bacillus mycoides | Pale blue-green, no halo |
| Escherichia coli, Candida albicans | Inhibited |
Technical data
| Preparation | 40 g in 950 mL; autoclave 121 °C 15 min, cool to about 50 °C and add the Chromogenic Bacillus cereus Supplement |
| Final pH | 7.2 ± 0.2 |
| Incubation | 35–37 °C, 24 h |
| Storage | 2–8 °C, dry and protected from light |
| Shelf life | 2 years |
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 Chromogenic Bacillus cereus Agar: Add the Chromogenic Bacillus cereus Supplement as stated on its label to the base cooled to about 50 °C.
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.
Chromogenic Bacillus cereus 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 Chromogenic Bacillus cereus Agar, please send us a request. With every delivery of Chromogenic Bacillus cereus Agar you receive the lot number and expiry date, and on request we send the available documentation for Chromogenic Bacillus cereus Agar.
Where Chromogenic Bacillus cereus Agar 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 |
|---|---|---|
| Chromogenic Bacillus cereus Agar | PRO7583 | 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
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.
