Microbiology Disinfectant Lab: Questions and Experiments

BIOL455 General Microbiology

Question:

Microbiology

Disinfectant Lab

1. What is the pupose of using the disc?

2. How are we meaning what is an effective versus an ineffective disinfectant?

3. Look at a plate that tested hydrogen peroxide. Explain how hydrogen peroxide functions as a disinfectant.

4. Overall- in general, how do microbes rank as far as their resistance or susceptibility to disinfectants.

5. From lecture, provide 2 examples of disinfectants that target bacterial proteins. Do any of yow disinfectants fall in this category?

6. From lecture, provide 2 examples of disinfectants that target bacterial plasma membranes. Do any of yow disinfectants fall in this category?

7. Define disinfection. How does this definition compare to: sterilization, antisepsis, and degerming.

8. What do your results indicate about the relative chemical resistances of the two organisms you tested? Are your results what you expected?

Antiseptics and Disinfectants

- Micrococcus luteus
- Pseudomonas aeruginosa

This experiment is not in lab manual.Media and Sug Dlies needed Der Derson:

- Two NA talls (incubate 24 or 48 hrs.)
- Two sterile plates
- Two sterile cotton swabs
- Four watch glasses
- Four different solutions to test (Hydrogen Peroxide, Mouth Wash, Bleach, etc.)
- Sterile filter paper discs
- Forceps.

For the “antiseptics & disinfectants” experiments, each of you will test 4 substances. Students should bring substances Lom home such as contact lens cleaner, mouthwash, or liquid soap or hand sanitizer (all substances tested must be liquid).Each smdent gets 4 watch glasses — each watch glass should contain a r Each smdent will need 2 NA talls & 2 sterile coton swabs.Each smdent should do one pow plate with Micrococcus luteus & one pour plate with Pseudomonas
aeruginosa.Melt 2 NA talls and pour into 2 sterile glass plates. When the Agar has solidified, dip sterile swab in mbe of culture (e.g. Micrococcus) then Peak

all over swface one of NA plates. streaked with Pseudomonas.The second of NA plate should be After the bacteria is streaked on the surface of agar, you should use forceps to touch the edge of a sterile filter paper disc to the liquid in each watch glass. Do not dip the disc in the liquid. Discs are then placed on the agar.

The plates should look like this:

Each filter paper disc has a different solution (Hydrogen Peroxide, Mouth Wash,Students must test the same 4 substances on each plate.