KG Agar Base is recommended for promoting fast and free sporulation to distinguish between Bacillus cereus and Bacillus thuringiensis. It is also recommended by APHA. Peptone and yeast extract in the medium supports the growth of B.cereus, B.thuringiensis. Lecithinase activity is observed as an opaque zone surrounding the individual colony. B.cereus is resistant to Polymyxin B, which restricts gram-negative organisms. B.cereus and B.thuringiensis can be distinguished by means of microscopic examination of stained cells. B.thuringiensis shows endotoxin crystals in sporulated cells.
1.Kim H. V. and Goepfert J. M., 1971, Appl. Microbiol., 22:581. 2.Downes F. P. and Ito K., (Eds.), 2001, Compendium of Methods for the Microbiological Examination of Foods, 4th Ed.,APHA, Washington, D.C.