Cellobiose Arginine Lysine Broth (CAL Broth) is recommended for isolation and biochemical characterization of Yersinia enterocolitica. It is a differential medium as it differentiates Yersinia on the basis of cellobiose fermentation and lysine or arginine decarboxylation. CAL Agar is generally used for the isolation and characterization of Y.enterocolitica from faecal specimens as the organism is biochemically similar to other Enterobacteriaceae. It is used for the enumeration of Y.enterocolitica from water and other liquid specimens. L-arginine and L-lysine are the amino acids, decarboxylation of which makes the medium differential.