MacConkey Sorbitol Agar
MacConkey Sorbitol Agar is recommended for the isolation and detection of pathogenic Escherichia coli strains. Pancreatic Digest of Casein, Peptic Digest of Animal Tissue, and Enzymatic Digest of Gelatin provide nitrogenous sources. D-Sorbitol is the fermentable carbohydrate. Crystal Violet and Bile Salts inhibit Gram-positive organisms and allow Gram-negative organisms to grow. Due to the presence of the Neutral Red pH indicator, coliforms that ferment Lactose turn dark red to purple color while non-fermenters are colorless. Sodium Chloride maintains the osmotic balance and Agar is the gelifying agent.