Bright cherry red color is produced upon the addition of methyl red indicator to a culture of a Gram negative bacilli in MR-VP broth if the organism used the mixed acid pathway of fermentation.
What is MR-VP test?
As part of the IMViC testing, Methyl Red (MR) and Voges-Proskauer (VP) broth is utilized as the medium in which both the Methyl Red and Voges-Prosakuer tests can be conducted.
It is a straightforward broth made up of dextrose or glucose, buffers, and peptone.
In the Methyl Red test, an infected tube of MR-VP broth is mixed with the pH indicator methyl red.
The acids will overwhelm the buffers in the medium and create an acidic environment if the organism employs the mixed acid fermentation pathway and creates stable acidic end products.
If acidic end products are present when methyl red is introduced, the methyl red will remain red.
Learn more about the MR-VP test with the help of the given link:
