m-FC Agar is used with Rosolic Acid for the cultivation and enumeration of fecal coliforms by the membrane filter technique at elevated temperatures. Enzymatic Digest of Casein, Meat Peptone, and Yeast Extract supply nitrogenous compounds, carbohydrates, vitamins, and minerals. Lactose is the fermentable carbohydrate. Bile Salts inhibit the growth of Gram-positive bacteria. Rosolic Acid increases specificity when high levels of non-coliform may be present in the sample, while Aniline Blue distinguishes fecal from non-fecal coliforms because the former produce an acid that reacts with the dye and shifts its color to blue. Agar is the gelifying agent.