Buffered Phosphate Broth (Twin Pack) is recommended for the cultivation and differentiation of microorganisms based on coagulation and proteolysis of casein. The medium is used for cultivation and enumeration of microorganisms encountered in dairy industry. Skim Milk is sometimes used as a complete medium or as an ingredient in other media used for propagation of organisms occurring in milk products. Proteolytic bacteria hydrolyze casein to form soluble nitrogenous compounds indicated as clear zone surrounding the colonies on agar media and shows separation of solids in liquid media.