Methyl Red Voges-Proskauer Test Lab

Tetia Richardson
Microbiology DL3: Instructor Newton
3/29/2015

PURPOSE
This experiment is designed to become familiar with and perform the MR-VP biochemical test, learn variations in how different organisms metabolize glucose, and to become familiar with and perform the catalase biochemical test.

Materials Used
10% bleach solution
Hydrogen peroxide
Paper towels
Saved E. coli culture
Stock culture: S. epidermidis
Gloves
Candle used for a flame source
Test Tube
Test Tube rack
Pipet
Slide-Box-MBK with blank slides
2 Broth, MR-VP - 5 mL
1 Barritt’s A Reagent - 3 mL in Pipet
1 Barritt’s B Reagent - 3 mL in Pipet
Methyl Red Reagent, 0.1% - 1 mL in Pipet
1 Inoculation Loop, Plastic
1 Mask with Earloops

PROCEDURE
Exercise 1
Procedural Steps
The saved E. coli culture and S. epidermidis stock culture was incubated 12-24 hours prior to the start of the experiment.
The work area was disinfected with 10% bleach solution.
The MR-VP tubes were labeled: one E coli and the other S epidermidis.
Each MR-VP broth tube was inoculated with the corresponding organism using aseptic techniques.
The tubes were incubated for 48 hours at 35oC-37oC
The reagents were allowed to warm to room temperature
Two test tubes were labeled E. coli and two test tubes were labeled S. Epidermidis
Half (2.5 mL) of the incubated MR-VP broth labeled E. coli was transferred into the two corresponding test tubes. This was repeated for the broth labeled S. epidermidis.
One tube for each organism was chosen for the Methyl Red test and labeled accordingly.
Using the pipet, six to eight drops of Methyl Red reagent was added to each of the tubes. If the test was positive, the red-pink color of acid presence from glucose appeared within seconds.
The remaining two tubes were for the Voges-Proskauer test. Twelve drops of Baritt’s A