VIOLET RED GLUCOSE AGAR

Violet Red Bile Agar is a selective and differential medium for isolation, detection and enumeration of coli-aerogenes bacteria from water, milk and dairy products, food stuffs and clinical samples. It is especially helpful for the examination of milk and other food products. It can be employed for the presumptive identification of coliforms according to APHA methods.
The medium contains peptone and yeast extract which supply nitrogen, sulphur, carbon, vitamins, minerals and other nutrients needed for the growth of the micro-organisms. The selective properties of the bile salt mixture and crystal violet inhibit many Gram-positive microorganisms, but allow the target Gram-negative organisms to develop.
The fermentable carbohydrate is glucose. Microorganisms that can ferment glucose produce acid. Neutral red is the pH indicator incorporated in the formulation to indicate acid production. Strains fermenting glucose normally produce red colonies surrounded by pink-red halos, giving a visual confirmation of fermentation.
Sodium chloride maintains the osmotic balance and agar imparts the solidifying property that enables the development and enumeration of colonies. Therefore the medium can be used for the routine microbiological examination of samples, wherein detection and enumeration of coliform organisms are desired.

A selective and differential medium for detecting, isolating, and enumerating coli-aerogenes bacteria in water, dairy products, food materials, and clinical samples.