KG AGAR BASE

Bacillus cereus, a gram-positive rod shaped and beta haemolytic bacteria, is widely distributed in nature and can be isolated from a variety of foods. B. cereus is classified as a large-celled species of Group I bacilli (species with a cell width greater than 0.9?m and whose spores do not appreciably swell the sporangium). KG Agar Base formulated by Kim and Goepfert and recommended by APHA is used to promote free spore formation of B. cereus, Bacillus thuringiensis within an incubation period of 20-24 hours. This feature allows a) direct confirmation of zone forming organisms as Group I bacilli by means of microscopic examination and b) immediate differentiation of B. cereus from B. thuringiensis by visualization of the endotoxin crystal in sporulated cells of the latter organism. Additionally, Group 2 bacilli such as Bacillus polymyxa, which produce lecithinase, are unable to form lecithinase under the rather nutritionally poor conditions imposed by KG Agar Base.

for di?erentiation of Bacillus cereus and Bacillus thuringiensis based on fast sporulation