What organic molecule is necessary to detect mixed acid fermentation by bacteria? (IMViC Tests)
To detect mixed acid fermentation by bacteria through the IMViC tests, the organic molecule necessary is methyl red (MR).
The IMViC tests (abbreviation for Indole, Methyl Red, Voges-Proskauer, and Citrate) are a set of biochemical tests used to differentiate between closely related species of bacteria based on their metabolic characteristics.
To specifically detect mixed acid fermentation, you would perform the Methyl Red test. This test determines the ability of bacteria to produce stable acids as byproducts of glucose metabolism. Mixed acid fermentation is characterized by the production of a mixture of several acids such as acetic, formic, lactic, and succinic acids.
To conduct the Methyl Red test, follow these steps:
1. Inoculate a test tube containing glucose broth with the bacteria you want to test for mixed acid fermentation. Incubate the tube for several hours at an appropriate temperature (usually 37 degrees Celsius) to allow bacterial growth.
2. After incubation, add a few drops of methyl red indicator to the broth. Methyl red will turn red at a low pH (acidic conditions).
3. Observe the color change of the broth. If the bacteria have undergone mixed acid fermentation and produced stable acidic byproducts, the broth will turn red due to the low pH resulting from the acid production.
So, to answer your question, the organic molecule necessary for detecting mixed acid fermentation by bacteria in the IMViC tests is methyl red.