Bacillius cereus Selective Agar (PEMBA)
This is a medium for the selective isolation and enumeration of Bacillus cereus in food samples. It is said to be particularly suitable for the detection of small numbers of Bacillus cereus particularly in the presence of other contaminating organisms. The medium is made selective by the inclusion of Polymixin and Sodium Pyruvate is also present which is said to improve Egg Yolk precipitation and enhance sporulation. As Bacillus cereus is Mannitol Negative the colonies are bluish in colour, due to the presence of the Bromothymol Blue Indicator, with a surrounding precipitate of the same colour due to Lecithinase production (from the Egg Yolk).
NB: It should be noted that some Proteus spp. and gram positive cocci may grow on this medium.