MR-VP (Methyl Red Voges-Proskauer) Broth Medium used in differentiating coliform organisms based on the Methyl Red and Voges-Proskauer tests. Enzymatic Digest of Casein and Animal Tissue supply nitrogenous sources, vitamins, and electrolytes for bacterial growth. Dextrose is the fermentable carbohydrate and Potassium Phosphate serves as pH buffer. Addition of the pH indicator Methyl Red allows to distinguish Glucose-fermenting organisms likeEscherichia coliand mostEnterobacteriacea(pH lowering shifts color to red) from non-fermenting bacteria likeKlebsiellapneumoniaeandEnterobacteraerogenes(red color is not developed). In the Voges-Proskauer test, Glucose fermentation by organisms likeE.coliand further metabolization of Pyruvic Acid to diacetyl is detected by the conversion of this end product into a red complex through the action of alpha-naphtol and creatine.