Date: Wednesday, September 5th, 2018

Title: Plaque Assay Evaluation and Soil B Collection

Rationale: The purpose of today’s lab was to check on our plaque assays from the previous lab and collect new samples of soil to test in order to work towards an answer to our class question.

Class Question: Is there a difference in bacteriophage presence or type in soil samples taken from live oaks vs those from red oaks?

Procedure:

1. We began by removing our plaque assays from the incubator.
2. Upon viewing the plaque assay, my plate had negative results. The plate was covered with a vein-like layer of agar. It’s possible I didn’t let the agar harden long enough before moving the plate to the incubator or that my measurements for making the agar were incorrect.
3. Next I went outside with my group to find a live oak to take samples from.
4. We chose a large live oak at coordinates 31°32’57” N 97°6’54” W.
5. Using a tape measure, we concluded that the circumference of the the tree at 137 cm from the ground was 299 cm.
6. The canopy was 1,672 cm at its largest and 912 cm at its smallest, averaging out to 1,292 cm in diameter.
7. We used shadows and trigonometry to determine the tree height. Since I stand at 6’1″ tall, converted this to 182.5 cm. My shadow was measured to be 173 cm. The tree’s shadow was 1013 cm, so using similar triangles we determined that the tree was 1068.64 cm tall.
8. We placed a soil sample and a tree leaf into a plastic bag labelled BJR 9-5-18 Soil B and transferred dirt from the bag into a 15 mL conical to the 2 mL mark.

Observations:

• My plaque assay was webbed.

Results:

• My plaque assay was negative and the control plate was clean therefore I didn’t have a phage in Soil A.
• This lab day yielded me a new soil sample to test for phages.

Next Step:

• My next step is to wash, filter, and enrich the sample for phages.