Rationale: Since I had washed soil from tree E earlier, I was able to run a plaque assay this class.

Procedure:

1. Divided lysate equally between tubes and spun at 3000g for 5 minutes.
2. Filtered 1.5mL using 0.22mm filter.
3. Pipetted 10mL of filtered lysate into 0.5mL of arthrobacter and let sit for 15 minutes.
4. Made top agar by placing 4mL LB Broth, 45mL of CaCl₂, and 5mL of 2X TA in a 50mL tube and pipetting up and down to mix.
5. Poured 4.5mL into top agar control plate then added arthro to remaining solution.
6. Mixed by swirling gently then poured into plate.

Observations:

Once again, my plaque assay turned up negative. My control was contaminated with something that didn’t look like arthro. I checked the 2X TA that I was using, and it turned out to be contaminated so I will have to use a different bottle moving forward and clean my micro-pipette tips.

Interpretations and Next Steps: Since this was my last chance to conduct a plaque assay or spot test, I will have to try another way to find phages in my soil samples. One such way is PCR. Starting next class, I will find a soil sample and enrich so that I can try to find phage with PCR the following week.