Sorbitol Maconkey Agar Base，SMAC

It is used for isolation and culture of E. coli O157. Peptone provides carbon and nitrogen source and vitamins; Bile salts, crystal violet, and thiosemicarbazone primarily inhibit the growth of Gram-positive bacteria; Potassium methylerucate inhibits the growth of Gram-negative bacteria except O157; Bacteria in use of sorbitol can produce acid, turning pH indicatior and the bacteria red. E. coli O157 does not use sorbital, so it is colorless in this medium.