Bacillus Cereus Agar Base

Bacillus cereus Agar Base (Mossel Agar / PEMBA)

Selective & Differential Medium for Isolation and Enumeration of Bacillus cereus Group

Catalog Number: AS-1129

Overview

Bacillus cereus Agar Base, commonly referred to as Mossel Agar and known as PEMBA when supplemented, is an internationally recognised selective and differential solid culture medium for the isolation and enumeration of members of the Bacillus cereus group.

When supplemented with polymyxin B and egg-yolk emulsion, the medium enables reliable differentiation based on mannitol non-fermentation and lecithinase activity, producing characteristic colony morphology. This medium is widely referenced in ISO 7932, FDA-BAM Chapter 14, and national food microbiology standards.

Ausamics Bacillus cereus Agar Base is manufactured to provide high selectivity, reproducible performance, and clear colony differentiation for food, environmental, and quality-control laboratories.

Key Features & Benefits

• Selective inhibition of competing microflora

• Differential detection based on mannitol fermentation and lecithinase activity

• Characteristic colony appearance for Bacillus cereus group

• Highly specific and reproducible results

• Suitable for standardised and reference testing workflows

Typical Applications

Food Microbiology

• Enumeration of Bacillus cereus group in cereals, rice, pasta, dairy products, spices, infant formula, and powdered foods

• Quality-control testing in food manufacturing

Environmental & Hygiene Monitoring

• Screening of environmental samples

• Assessment of production and processing environments

Research & Reference Laboratories

• Use in methods aligned with ISO and FDA guidance

• Comparative and method-validation studies

Principle of the Medium

The basal medium contains mannitol, bromothymol blue, and nutrients to support growth. When supplemented:

• Polymyxin B inhibits Gram-negative bacteria and many Gram-positive competitors

• Mannitol non-fermentation maintains a red/pink background

• Egg-yolk emulsion allows detection of lecithinase activity

Members of the Bacillus cereus group typically produce turquoise to peacock-blue colonies surrounded by an opaque egg-yolk precipitation halo, while non-target organisms are inhibited or form small, non-characteristic colonies.

Composition (Typical, Base Only – per litre)

• Peptone: 10.0 g

• Mannitol: 10.0 g

• Sodium chloride: 5.0 g

• Magnesium sulfate: 0.1 g

• Disodium phosphate: 2.5 g

• Monopotassium phosphate: 0.25 g

• Bromothymol blue: 0.12 g

• Sodium pyruvate: 1.0 g

• Agar: 15.0 g

Final pH at 25 °C: 7.2 ± 0.2

Supplements (Added After Sterilisation)

• Polymyxin B supplement: 100,000 IU/L

• Egg-yolk emulsion (50 %): 100 mL/L

Preparation (Typical)

• Suspend 43.97 g of dehydrated base in 900 mL purified water

• Heat to boiling until completely dissolved

• Autoclave at 121 °C for 15 minutes

• Cool to 50 °C

• Aseptically add polymyxin B and sterile egg-yolk emulsion

• Mix thoroughly and pour into sterile Petri dishes

Typical Colony Appearance

(After 24–48 h incubation at 30–32 °C)

• Bacillus cereus group:
  3–7 mm, turquoise to peacock-blue colonies with rough/matte surface and wide egg-yolk precipitation halo

• Other organisms:
  Inhibited or small pink/red colonies without halo

Storage & Stability

• Dehydrated base: Store below 30 °C, dry, protected from moisture

• Prepared plates: Store at 2–8 °C, protected from light; use within recommended shelf life

Intended Use

For laboratory food, environmental, and research microbiology use only.

Not for human, animal, diagnostic, or therapeutic use.

Quality & Compliance

• Reference medium aligned with ISO 7932 and FDA-BAM Chapter 14

• Manufactured under controlled conditions for batch consistency

• Certificate of Analysis (COA) available

• Safety Data Sheet (SDS) available upon request