The Bacillus cereus Supplement, a product by Liofilchem®, is designed for the selective isolation of Bacillus cereus from food samples. This supplement, available in a kit containing 10 vials of freeze-dried Polymyxin B, is essential for enhancing the selective enrichment of media recommended for isolating Bacillus cereus, such as the Bacillus cereus Agar Base.
Composition and Principle
Each vial of Bacillus cereus Supplement contains Polymyxin B, an antibiotic that inhibits bacterial flora potentially present in food products without interfering with the growth of Bacillus cereus. The concentration of Polymyxin B in each vial is 50000 IU, which increases to 100000 IU per liter of the prepared medium. The selective action of Polymyxin B makes the supplement an effective tool for isolating Bacillus cereus, a significant concern in food safety.
Procedure for Use
The supplement is easy to use. The freeze-dried contents of one vial are aseptically reconstituted with 5 ml of sterile distilled water. This solution is then added to 500 ml of prepared Bacillus cereus Agar Base, either the Mossel or PEMBA formulations. The mixture is carefully distributed into Petri dishes for further analysis. The simplicity of the procedure makes it accessible for routine use in professional laboratory settings.
Quality Control and Interpretation of Results
Quality control of the Bacillus cereus Supplement involves visual and microbiological checks. The freeze-dried product should appear white. For microbiological control, the prepared medium is inoculated with control strains such as Escherichia coli (ATCC 25922) and Bacillus cereus (ATCC 11788 and ATCC 14579). The expected result is the inhibition of Escherichia coli and good growth of Bacillus cereus, typically presenting red colonies in the Mossel medium. This control process ensures the supplement’s effectiveness in selectively isolating Bacillus cereus.
Storage and Precautions
The supplement should be stored at 2-8°C in its original packaging, away from heat sources and excessive temperature changes. It remains effective until the expiry date on the label, provided storage conditions are met. The product is intended for professional use only, and operators should be trained in laboratory methods. The handling instructions and the Safety Data Sheet (SDS) must be followed to ensure safe and effective use.
The Bacillus cereus Supplement is a crucial component in the microbiological analysis of food products, offering a reliable and efficient means of isolating Bacillus cereus. Its ease of use, combined with stringent quality control measures, ensures its reliability and effectiveness in laboratory settings, contributing significantly to food safety monitoring.