m Endo Agar, LES is used for enumerating coliforms in water by membrane filtration. Enzymatic Digest of Casein and Yeast Extract provide nitrogenous compounds and vitamins, being Lactose the fermentable carbohydrate. The combination of Sodium Sulfite, Sodium Deoxycholate, and Basic Fuchsin suppresses the growth of many Gram-positive and Gram-negative microorganisms. Sodium Lauryl Sulfate acts as a selective agent against non-coliform organisms. Lactose-fermenting coliforms produce pink-red colonies with a characteristic green sheen, while those bacteria unable to ferment this sugar form pale pink or colorless colonies. Sodium Chloride is used to maintain the osmotic balance of the medium and the Potassium Phosphates act as buffering agents. Agar is the gelifying agent.