Methyl Red Test and Voges-Proskauer Test

The Methyl Red test determines the ability of some bacteria to ferment glucose due to mixed-acid fermentation. While the Voges-Proskauer test determines the ability of some bacteria to ferment glucose via butanediol fermentation.

First we used the aseptic technique to inoculate the MR-VP (methyl red/Voges-Proskauer) broth tube with a loopful of bacteria from our agar slant culture.

Then we incubated the inoculated tube at 35 degrees Celsius for two days. 

After two days we came back to lab and divided the MR-VP broth into two tubes so that we could use the broth to use for another test. For one of the tubes we added 6 drops of the methyl red to the tube. We then gently swirled the tube to mix the broth culture and the pH indicator

After we mixed the broth culture and the pH indicator we read the reaction immediately and we found that our test was positive.

Then we took the other tube of the MR-VP broth and added 15 drops of Barritt's reagent A (alpha-naphthol) and 5 drops of Barritt's reagnet B (KOH) to the tube.






















We then tapped the bottom of the tube vigorously so that the oxygen in the air aerates the medium.

Afterwards we put the tube back in our rack for about 30 minutes. After 30 mines we read our results and found that our bacteria was positive which means that our bacteria used the butanediol fermentation pathway.