Violet Red Bile Agar

Violet Red Bile Agar is used for the detection and determination of coliforms in food, milk, water, and other sanitary materials. It is a selective medium which detects the growth of lactose fermenting coliforms. Neutral red within this formulation acts as a pH indicator while Crystal Violet and Bile Salts inhibit the growth of gram-positive microorganisms. Coliform colonies lower the pH of the medium subsequently causing their colonies to look red (Neutral Red Dye) and to precipitate the bile salts.