Isolation of Bacteria

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Isolation of Bacteria in our Physical Environment

Introduction:
The purpose of the lab is to apply what has been learned so far in Microbiology, and use it to collect and examine microbial species from the physical environment. The physical environment around the lab will be utilized to find out the variety of different microbial species growing in and around the lab. This investigation will help in preparation for the individual projects that will be done at the end of the semester.

Materials and Methods:
The lab chosen was Exercise 24: Isolation of Bacteria in our Physical Environment. For this lab, four TSA Petri plates, a test tube of sterile water, and sterile cotton swabs were obtained. The Petri plates were labeled 1-4. Plate number 1 was left on the lab bench for the duration of class. It was labeled “air sample”. Plate number 2 was divided in half, side 1 contained the steering wheel sample, and side 2 contained the cell phone sample. Plate number 3 was also divided in half, one side was labeled 3, which contained the sample from the door handle on the women’s restroom. The other half, labeled 4, contained the sample from the button on the pop machine. Plate number 4 contained the sample from a dollar bill.

To obtain the samples, the sterile cotton swab was dipped into the test tube containing the sterile water, it was then swabbed onto the surface being tested. Then the cotton swab was streaked out into one section of the Petri plate. The cotton swab was then thrown in the trash. The bacterial loop was then used to make the second and third streaks on the plate. After each streak, the loop was sterilized in the Bunsen burner. The lid was then replaced onto the Petri plate, and was moved to the incubator for 48 hours at 35 degrees Celsius. The same procedure was used on all of the samples.

Following the 48 hour incubation period, the Petri plates were observed for colony morphology, and the results were recorded. A Gram...
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