The Ubiquity of Microorganisms PDF

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Ubiquity of Microorganisms (12 pts) In our everyday common experiences, microbes are virtually ubiquitous. They are in the air we breathe, the foods we eat, and the water we drink. Microorganisms contaminate the surfaces of objects that we use (like this sheet of paper) as well as the skin of our fingers. In practical terms, the only places where microorganisms are not found are places where we intentionally exclude them. During the semester you will need to describe bacterial (or fungal) growth observed on slants or Petri plates. You will need to learn the teminology used for describing common colony types. The following outline will be helpful for verbally communicating the appearance of observed colonial growth. 1. Morphology: Refers to the shape of the colony. These forms represent the most common colony shapes you are likely to encounter.

2. Size: The diameter may be measured (mm). Tiny colonies are referred to as punctiform. 3. Surface: Bacterial colonies are frequently shiny and smooth in appearance. Other surface descriptions might be: veined, rough, dull, wrinkled (or shriveled), glistening. 4. Texture: Several terms that may be appropriate for describing the texture or consistency of bacterial growth are: dry, moist, mucoid, brittle, viscous, butyrous (buttery). 5. Color: It is important to describe the color or pigment of the colony: white, cream, greenish, etc. Also include descriptive terms for any other relevant optical characteristics such as: opaque, cloudy, translucent, iridescent.

6. Elevation: This describes the “side view” of a colony. These are the most common.

7. Margin: The margin or edge of a colony (or any growth) may be an important characteristic in identifying an organism. Several examples are shown below.

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Materials (Per table): 4 typtic soy agar plates (TSA) Procedure: Lab 1: 1. Each person at the table choose one of the following methods of inoculating their TSA plate (each must choose a different method!): a. Plate # 1: Touch the surface of the plate with the tips of your fingers (try to get the area under the fingernails, it has the best stuff!). b. Plate # 2: Using sterile saline and a sterile cotton swab, moisten the swab and sample an area or object of your choice. Cell phones, door knobs, bottom of your shoe, etc are excellent choices. Use the swab to inoculate the agar surface. c. Plate # 3: Cough on the plate several times. d. Plate # 4: Using a cotton swab, sample the inside of your mouth along the gum area and roll the swab onto the agar surface.

2. Incubate plates # 1 and 2 at 25 ºC for 48 hours. 3. Incubate plates # 3 and 4 at 37ºC for 48 hours.

Lab 2: 1. Observe and record growth on all 4 plates. Describe three different colonies from each plate using all 7 cultural characteristics discussed above. ****If you do not have three different colonies on any of your plates, observe another table’s plate of the same method.

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Name _________________________________

Lab Section _________

Results: 12 pts. (1 pt for the complete description of each colony) Plate #1 - Fingers

Colony 1

Colony 2

Colony 3

Morphology: Size: Surface: Texture: Color:

Elevation: Margin:

Plate #2 - Object Morphology: Size: Surface: Texture: Color:

Elevation: Margin:

3

Plate #3 - Cough

Colony 1

Colony 2

Colony 3

Colony 1

Colony 2

Colony 3

Morphology: Size: Surface: Texture: Color:

Elevation: Margin:

Plate #4 - Mouth Morphology: Size: Surface: Texture: Color:

Elevation: Margin:

4...