This medium is recommended for selective isolation and enumeration of Clostridium perfringens in food. Tryptone, yeast extract, Soya peptone and HL extract supply most of the essential nitrogenous nutrients, vitamin B complex and trace ingredients for the growth of C.perfringens. Sodium metabisulphite and ferric ammonium citrate are used as indicators of sulphate reduction by C. perfringens, which produces black colonies.