Bacillus cereus (MYP) agar is intended for the selective enumeration of Bacillus cereus in food samples. This medium utilizes two reactions namely mannitol fermentation and lecithinase production to differentiate Bacillus cereus from other related species. As B. cereus is mannitol negative the colonies are pink in colour due to the presence of the phenol red pH indicator. Lecithinase production (from the addition of egg yolk) is indicated by a white precipitate around the colonies. This medium meets the requirements of ISO 7932:2004.
Beef extract and peptone provide the required carbon, nitrogen and vitamins. Sodium chloride helps maintain the osmotic balance and phenol red is the pH indicator. Mannitol is a fermentable carbohydrate. The medium is made selective by the inclusion of polymyxin B sulphate (LS0020).
NB: This is a basic medium only and contains no additional supplement. It should be noted that some Proteus spp. and Gram-positive cocci may grow on this medium.