Violet Red Bile Glucose Agar, VRBGA

Violet Red Bile Glucose (VRBG) Agar is a selective and differential culture medium which is used to count and isolate Enterobacteriaceae. It is a variation of MacConkey Agar in which lactose is replaced with glucose.
The medium contains differential and selective agents. Gram-positive bacteria cannot grow in the presence of bile salts and crystal violet because they are selective agents. The only carbohydrate source is glucose, which allows for differentiation according on fermentation ability. Yeast extract and peptone provide vital nutrients for the growth of microorganisms.
Because Enterobacteriaceae ferment glucose quickly, they produce acid that reacts with neutral red, a pH indicator, to form red colonies that are frequently encircled by a reddish-purple precipitate of bile salts. Because lactose is not present in VRBG agar, it is not possible to distinguish between coliforms that ferment lactose and those that do not, which makes it appropriate for counting Enterobacteriaceae rather than individual coliform groups.
The microbiological evaluation of food, pharmaceutical, and cosmetic products frequently uses VRBG agar.

Storage
Keep the container at 15-30 °C and prepared medium at 2-8 °C.