Studying Soil Bacteria. Microbiology Lab.

Essay by mckrackinHigh School, 11th grade January 1996

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Studying Soil Bacteria: Microbiology Lab


The object of this microbiology lab is for the purpose of learning the classification of bacteria and all of the procedures required to determine classification. The examination of soil is due to the fact that there are too high of a risk of culturing pathogens when the samples are taken from the classroom. The data recorded for this lab consist of in order: metabolic descriptions, colony descriptions, morphology, and histological characteristics.


Collection of Soil Bacteria:

1. Crush into a fine powder 1-2 grams of soil.

2. Add soil to 5 ml of sterile water.

3. Shake

4. Allow the soil to settle for 30 seconds to 1 minute

5. Flame a loop in a blue bunsen burner flame.

6. Cool the loop by jabbing the loop into a portion of agar

7. Insert the loop into the soil suspension

8. Remove the loop, making sure that a droplet of soil suspension is still on the loop

9. Use this drop of soil suspension to plate streak, onto the agar plate

Plate Streaking Procedure

1. Using a permanent marker, record the name of your group on the bottom of an agar plate. It is also advisable to include the date.

2. The inoculating loop is to be held as you would hold a pencil in the hand that you write with.

3. Sterilize the loop using a blue bunsen burner flame until the loop glows red. When this occurs you are to pass the lower 2/3 of the loop's shaft through the flame.

4. Cool the loop for 5-10 seconds. Do not put the loop down.

If your work is being done from a petri dish culture continue the previous steps with the following:

5. Lift the lid from the petri dish with the...