Bacillus-cereus-selektiv-agar (BCSA)
Bacillus cereus: Typical blue colonies surrounded by an egg yolk precipitate.		Bacillus subtilis: The colonies are green and there is no egg yolk precipitate.
This is a selective and diagnostic medium used for the isolation and enumeration of Bacillus cereus. The medium contains Polymyxin B which inhibits Gram-negatives. Bacillus cereus forms blue colonies on this medium because it is unable to utilise mannitol and does not cause a fall in pH (indicator is bromthymol blue). The colonies are surrounded by a zone of egg yolk precipitate due to production of lecithinase. Bacteria that utilise the mannitol produce yellow colonies.