MR-VP Broth (Glucose Phosphate Broth) is supplied by HiMedia. It is a sterile ready prepared media containing 5ml of light-yellow coloured solution in bottles. MR-VP Broth (Glucose Phosphate Broth) is generally used for the performance of Methyl Red and Voges Proskauer tests in differentiation of coli-aerogenes group. It is advisable to store this ready prepared media between 2-8C. Composition (in gm/L) is as follows:

Buffered peptone (7.00)

Dextrose (5.00)

Dipotassium phosphate (5.00)

Ready prepared MR-VP broth can be used for studying biochemical tests, namely MR and VP tests. They are used to differentiate amongst coliaerogenes group. This medium contains buffered peptone water, which supports growth of organisms. Dextrose serves as immediate carbon source. On growing the pure culture in the test medium after 18-24 hours the cultures are tested for MR and VP tests. MR test is performed by adding Methyl Red indicator. Methyl red is a pH indicator, which determines the pH when an organism utilizes glucose. If, on addition of one drop of methyl red indicator at the end of the period of incubation, there is a colour change to distinct red, it indicates positive test. Whereas if the reagent turns yellow or yellowish orange, it indicates negative test. VP test detects ability of the organism to produce a neutral end product acetyl methyl carbinol (acetoin) from glucose utilization. This test is done by adding 1-2 drops of Barritt Reagent A and 1-2 drops of Barritt Reagent B. A positive test is showed by pinkish red colour within 2-5 minutes. No change in colour indicates negative test.