Rationale: The purpose of this lab is to perform a plaque assay with Soil C to isolate possible plaques, and to collect soil metadata.

Description of Procedures:

1. The work station was cleaned using aseptic technique and an ethanol burner was lit to create an aseptic zone.
2. 10 ul of lysate was added to 0.5 ml of arthrobacter and allowed to sit for 10 minutes.
3. The top agar solution was then made with 8 ml of LB broth and 90 ul of CaCl2, to make enough top agar for four plates. The 2x TA was not yet added, because it would solidify before the arthrobacter had sat long enough.
4. Next, the % water was calculated. The dry soil was found to be 5.331 g. Therefore the mass lost was 0.519 g. With the original mass of 3.53, the % water was calculated to be 14.7%.
5. The composition of the soil was determined next. Out of the 7 ml of soil, 5.5 ml were sand, 1.0 ml was silt, and 0.5 ml was clay. The percent compositions are listed under data.
6. Next, 10 ml of 2x TA was added to the TA solution.
7. 4.5 ml of the top agar solution was added to each tube of arthrobacter, and this mixture was quickly poured onto a petri dish. The rest of the top agar solution was poured onto a control plate. The experimental plate was labeled LIP 9-24-18 Soil C, and the control was labeled Control LIP SS EAG 9-24-18.
8. The plates were allowed to sit for 15 minutes and then inverted and stored in the incubator until the next lab.
9. The work station was cleaned using aseptic technique and all materials were stored or properly disposed of.

Observations/Data/Results:

• Observation:
  • When the plates were poured, there were less bubbles than before. Only one was seen on the experimental plate.
  • The control plate had more bubbles.
• Data:
  • % Water- 14.7%
  • % Sand- 78.6%
  • % Silt- 14.28%
  • % Clay- 7.14%

Interpretations/Next Steps/Conclusions:

The plaque assay and soil metadata were completed for Soil C. The next step will be to check for plaques in the next lab. If plaques are found, they will need to be picked. If no plaques are found, a spot test will be performed to test Soil C once more.