m-FC Broth is a liquid medium used for the cultivation and enumeration of fecal coliforms by the membrane filter technique at elevated temperatures. Enzymatic Digest of Casein, Peptide Digest of Animal Tissue, and Yeast Extract supply nitrogenous compounds, carbohydrates, vitamins, and minerals. Lactose is the fermentable carbohydrate. Bile Salts inhibit the growth of Gram-positive bacteria. 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. Sodium Chloride maintains osmotic balance.