VIOLET RED BILE AGAR

Violet Red Bile Agar (VRBA) is a selective medium commonly used for the isolation of coliforms in samples of water, milk, dairy products and food. The medium is acknowledged by several standard testing authorities and is vital to quality control and hygiene monitoring in which coliform counts serve as indicators of sanitary condition of the environment and potential contamination.
The selectivity of the medium was attained by addition of bile salts and crystal violet which suppress the growth of many Gram positive organisms but permit growth of the coliforms. Lactose is the source of fermentable carbohydrate which allows differentiation on the basis of fermentation activity. Coliform organisms that rapidly ferment lactose produce characteristic red to purple colonies surrounded by a reddish halo, making them easy to identify and count. Organisms which do not ferment lactose generally produce pale colonies. Because of its dependable performance and well-defined colony morphology, VRBA is widely used as a standard medium for testing and enumerating coliforms in the food, dairy and water industries.

Selective agar medium that helps visualize and enumerate coliform bacteria in food, dairy, and water samples.