MR-VP (Methyl Red Voges Proskauer) Broth is recommended for use in the performance of Voges-Proskauer and Methyl Red tests as an aid in the identification of enteric Gram-negative bacilli.

• Methyl red is yellow at pH 6.2 and above, and red at pH 4.4 and below
• Particularly useful in the identification of Enterobacteriaceae

The same broth is used for both tests. The methyl red test detects production of acids formed during metabolism using mixed acid fermentation pathway with pyruvate as a substrate. The VP test uses alpha-naphthol and potassium hydroxide to test for the presence of acetoin.