Microbiology Environmental Microbiology- Ubiquity culture Objectives: Show that microbes are present everywhere in the environment. Specific objectives: Demonstrate the presence of microorganisms in different areas of the environment. Define the terms ubiquity, free-living, pathogen, and non-pathogen. Describe the correct labeling and incubation of a plate. Materials required: Trypticase soy agar (TSA) 2 plates per student. Work in groups of four. Tryptic soy broth (TSB) 1 tube Sterile swabs Specimen: Specimen collected from selected sites Procedure: Day 1: 1. Select a unique environmental site. We will brainstorm to identify various sites. Pick a site that you would expect to have repeated human contact without routine cleaning. i.e. soda machine buttons, door knobs, desk tops. Site selected: ____________________________________ 2. Label the plates as follows for your group: a. Cough plate: cough several times on the surface of the plate. b. Fingertips: rub fingers together and gently touch surface of the plate. c. Hair: vigorously scratch your head over the surface of an open plate. d. Countertop: wet swab and role swab over plate as demonstrated. e. The other four plates should be labeled from the sites you choose. Wet swab; obtain specimen as directed and role swab over agar surface. 3. Place the streaked plate into the provided incubator rack. Incubate under standard conditions. 4. An unopened plate and an opened plate will also be incubated. 5. Save plates for Colony Morphology experiment. Day 2: 1. Examine your plates for growth. On the reverse side, make drawings of what has grown on the plates. 2. If growth appears on the unopened plates, what are some likely explanations? What if growth only appeared on one plate? How does growth on unopened plates affect the reliability of the other plates?
Rev 3/2011
(1 pt.)
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Name: _________________________
Date:____________
3. Why were various types of specimens chosen for this exercise?
(1 pt.)
4. The plate you are using for this exercise will be autoclaved to completely sterilize them. The measures taken to disinfect the countertops are not as extreme. Why?
(1 pt.)
5. What is the clinical relevance of this exercise?