Environmental Microbiology Lab Report

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Collection, Observation, and Analysis of Microorganisms in the human environment

Introduction
The necessity and value of collecting, identifying, and analyzing the various microbes regularly encountered in the daily human environment becomes quite apparent when one gains even a very basic knowledge of how diseases are acquired and spread. The purpose of this lab was to collect and observe microbes from environmental and human body samples by culturing them on the appropriate media using aseptic transfer techniques.

Materials
• Distilled water
• Test tube
• 6 Unopened packages of 1 sterile cotton swab
• 2 sterile nutrient agar Petri dishes
• 1 sterile blood agar Petri dish
• Incubator
• Refrigerator
• Bunsen burner
• Gas connection
• Plastic tubing
• Inoculating loop
• 12 sterile glass slides

• Wax pencil
• Igniter
• Crystal violet dye
• Gram’s iodine
• Ethyl alcohol
• Safranin dye
• Paper towels
• Wire rack
• Sink
• Brightfield compound microscope
• Lens paper
• Immersion oil
• Pen and paper

Methods

I. Collecting the environmental specimens:
1. Place some distilled water into the test tube.
2. Open one package of sterile cotton swabs by peeling apart the packaging at the top. Do not peel the package apart completely, just at the top. 3. Take out the cotton swab, dip it into the test tube of distilled water, and place it back into the original package with the cotton tip facing down. 4. Repeat the previous two steps for three more unopened packages of sterile cotton swabs. 5. Choose four locations from which environmental samples can be taken. (For example, use the bottom of a shoe, a light switch, or a sink handle). Write these locations down on a piece of paper and number them E1-E4 for later reference. (For example, E1 is the sink handle). 6. At each location, take out one of the wetted sterile cotton swabs and rub it against a small area of the surface being sampled. Make sure to turn the swab as well to ensure that the sample is on all sides of the cotton swab. After swabbing, place each swab back into its original package, with the cotton tip facing downwards. Keep track of which swabs were used for which samples. Label them if necessary.

II. Collecting the throat and nose samples:
1. Place some distilled water into the test tube.
2. Open one package of sterile cotton swabs by peeling apart the packaging at the top. Do not peel the package apart completely, just at the top. 3. Take out the cotton swab, dip it into the test tube of distilled water, and place it back into the original package with the cotton tip facing down. 4. Repeat the previous two steps for one more unopened package with a sterile cotton swab. 5. Take one of the wetted sterile cotton swabs and rub it against the inside of one’s nose. Make sure to turn the swab as well to ensure that the sample is on all sides of the cotton swab. After swabbing, place the swab back into its original package, with the cotton tip facing downwards. 6. Repeat the previous step, but instead take a sample from the back of the throat.

III. Aseptic transfer of the environmental specimens:
1. Take the two nutrient agar Petri dishes and turn them bottom side up. Then, using a wax pencil, draw a line down the middle of each dish. Label each of these four sections E1, E2, E3, E4 so that the origin of each sample is known for later. 2. Take out one cotton swab that was used on an environmental surface out of its packaging. Keep this swab in one hand. 3. With the other hand, open the lid of one sterile nutrient agar Petri dish slightly at an angle. 4. Take the cotton swab in the other hand and gently swab it against...
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