Bacillus Cereus (Mannitol Egg Yolk Polymixin - MYP) Agar Intended for the selective enumeration of Bacillus cereus in food samples the medium uses two reactions (Mannitol fermentation and Lecithinase production) to differentiate Bacillus cereus from other members of the species. As Bacillus cereus is Mannitol Negative the colonies are pink in colour due to the presence of Phenol Red Indicator. Lecithinase production (from the Egg Yolk) is indicated by a white precipitate around the colonies. Polymixin is added as the selective agent to inhibit coliforms. NB: It should be noted that some Proteus spp and gram positive cocci may grow on this medium.