GN Broth is a liquid medium used for isolating and cultivating Gram-negative enteric microorganisms, especially Salmonella and Shigella spp. Enzymatic Digests of Casein and Animal Tissue supply nitrogen compounds and vitamins. Dextrose and Mannitol are the fermentable carbohydrates. The higher concentration of Mannitol over Dextrose favors growth of mannitol-fermenting Salmonella spp. and Shigella spp. over mannitol non-fermenting microorganisms such as Proteus spp. Mono- and Dipotassium Phosphates serve as buffering agents. Sodium Citrate and Sodium Deoxycholate inhibit the growth of Gram-positive bacteria and coliforms.