Weekly iLab iLab: Exploring the Microbiology Lab
FirstName Tiffani_LastName: Whitehead
Section 1 Lab Safety

1. There are four safety equipment items that a lab should have. Identify two of these four items. (2 pts) Biological Safety Cabinet, Eyewash and shower

2. Identify one of the three ways to keep your work area safe. (1 pt)
Keep your workspace free of all unnecessary materials

3. There are five recommendations for dressing properly in a lab environment. Name two of these recommendations. (2 pt) Avoid loose fitting items of clothing, Wear appropriate shoes sandals are not allowed.

4. There are several safety tips to protect one’s mucous membranes and broken skin. Identify one of the recommended tips. (1 pt) Do not apply makeup, put in contact lenses, or otherwise perform activities that might introduce lab organisms to your personal space.

5. When working in a microbiology lab, it is important to contain spills and discard materials properly. Describe how a spill should be cleaned up safely in a microbiology lab. (3 pts) 1. Wear a lab coat, disposable gloves, safety glasses or a face shield, and if needed, approved respiratory equipment. 2. Soak a paper towel(s) in an appropriate disinfectant (70% ethanol or fresh 10% bleach solution) and place around the spill area. 3. Working from the outer edges into the center, clean the spill area with fresh towels soaked in the disinfectant. Be sure to decontaminate any areas or surfaces that you suspect may have been affected by the spill. Allow 10 minutes contact time. 4. Place the paper towels and gloves into a biohazard bag and autoclave these materials to sterilize them. 5. Dispose of any contaminated clothing properly.

6. Describe the procedures that one must do before leaving the lab. (3 pts) Before leaving the lab, make sure all items have been returned to their appropriate location. After your work area is clear, wipe thoroughly with antimicrobial soap before leaving the lab. Do not remove any item from the lab unless you have been directed to do so by the lab instructor.

Section 2 Biochemical Tests

7. How do you know that no contamination occurred when you inoculated your culture? (1 pt) No growths that were unexpected developed. I.e. if it is a fluid base growth there should be no air born bacteria in the culture. No mold is another way to know no contamination occurred.

8. If the biochemical test requires an incubation of 24 hours, what do you need to do? (1 pt) Make sure the culture incubates for the full 24 hours before observation.

9. If your biochemical test requires that a reagent is added, which tool do you need to use? (1 pt) Separatory funnels

10. There are two ways to record the results of a biochemical test. Watch the video found in the Recording Results tutorial. What was the result of the acid from glucose test? (1 pt)
The culture changes to yellow in the presence of acids indicating a positive test

11. An important tool available in the Virtual Unknown program is the Identification Matrix. From the portion of the identification matrix shown in the Identifying Bacteria tutorial, identify at least one bacterium that has a positive result to the arabinose fermentation test. (1 pt)

Section 3: Reference Books 12. The first step of identification of an unknown bacterium is determining if the bacterium is gram negative or gram positive. (6 pts)

Using the information found in the Gram Negative Enteric Baccilli and Gram Positive Cocci Reference books, complete the following table:

Bacteria | Gram positive or negative? | Locations most frequently found | Identify at least one illness that bacteria can cause | Staphlococcus aureus | Gram positive | Skin hair | cellulitis | Proteus vulgaris | Gram negative | Soil, water,fecal matte | Urinary tract infections |

The following questions, which focus on the Dulcitol Fermentation Test, will help you explore these resources.

13. What is the purpose of the dulcitol fermentation test? (1 pt)

The purpose is to see if the microbe can ferment the carbohydrate (sugar) dulcitol as a carbon source

14. Which medium is used to perform the dulcitol fermentation test? What is the indicator used in this medium? (2 pts)

Several media are available for this. Most commonly used is phenol red dulcitol broth. The medium is a nutrient broth to which 0.5-1.0% dulcitol is added. The pH indicator phenol red is red at neutral pH but turns yellow at pH <6.8. It also changes to magenta or hot pink at pH >8.4. The medium is a nutrient broth to which 0.5-1.0% dulcitol is added. The pH indicator phenol red is red at neutral pH but turns yellow at pH 8.4. 15. After incubating the inoculated medium for 24 hours, the medium is yellow. Can the bacterium that you tested ferment dulcitol? (1 pt) A positive test consists of a color change from red to yellow, indicating a pH change to acidic. So yes.

16. Medium containing phenol red will be yellow when the pH is less than 6.8. Why would the medium change from a neutral pH to an acidic pH? (3 pts) The pH becomes acidic which causes a color change.