Biochemical Testing

NAME AND COURSE SECTION: Michele McNeill, Camile Manradge – Section 704

TITLE AND NUMBER: Biochemical Testing of Microbes – Lab #6

Exercise #1: Methyl Red-Voges Proskauer Test

Exercise #2: Motility Testing

Exercise #3: Carbohydrate Fermentation Testing

PURPOSE: We will prepare an E. coli culture, and further explore and become familiar with differential staining techniques using the Gram stain. We will use Crystal Violet dye, Iodine, acetone-alcohol, and Safranin to stain cells and differentiate between Gram-negative and Gram-positive bacteria (S. epidermidis, L. acidophilus, S. cerevisiae, and E. coli). Is to identify organisms.

PROCEDURE:

Pre-Experiment Preparation:

In preparation for the experiment, we put the E. coli and S. epidermidis stock culture in the incubator for 24 hours.

Exercise 1 – Methyl Red-Voges Proskauer Tests

• We first disinfect our work area to provide a safe and clean environment before we begin the lab process.

• We then removed two MR-VP broth tubes from refrigeration to bring them to room temperature in preparation for the experiment.

• Using a wax pencil, we labeled one of the MR-VP tubes E. coli, and the other S. epidermidis.

• We then used aseptic techniques to inoculate each tube with the corresponding organism. We then incubated both tubes for 48 hours.

• We then removed one tube of Barritt’s A Reagent, and one tube of Barritt’s B Reagent tubes from refrigeration to bring them to room temperature in preparation for the experiment.

• We then sterilized four test tubes in boiling water, and labeled two tubes E. coli, and two tubes S. epidermidis.

• We then transferred 2.5 mL of the incubated E. coli MR-VP broth into the two sterilized test tubes labeled E. coli. We repeated the same with S. epidermidis MR-VP broth for the two S. epidermidis test tubes.

• We placed the E. coli and S. epidermidis cultures in the refrigerator for use in future...