Results:

No contamination or strange patterns appeared this time. The plates were negative as shown in the pictures below.

Rationale:

A plaque assay will be run with soil E enriched lysate to determine whether or not there are bacteriophages in the sample that specifically target Arthrobacter.

Procedure:

1. Once an aseptic zone was established, the enriched filtered lysate from soil E was filtered with a 0.22 μL tipped syringe into a microcentrifuged tube labeled “KEA 10/12/18 FS enriched.”
2. 10 μL of “KEA 10/12/18 FS enriched” was added and mixed into a conical vial which already had 0.5 mL of Arthrobacter.
3. 4 mL of LB Broth, 45 μL of 1 M CaCl₂, and 5 mL of 2X TA were combined into a different conical vial.
4. Transferred and mixed 4.5 mL of the Top Agar mixture from the conical vial into the conical vial with the Arthrobacter and enriched lysate.
5. The conical vial mixture was poured onto the plate.
6. The “KEA 10/12/18 Soil E PA” plate was placed in the incubator at room temperature.

Observations:

• The following calculations were performed to determine enough LB Broth, 2X TA, and CaCl₂needed for 2 plates.

• MA plates were used instead of the regular agar plates to run the plaque assay because there was a shortage of the regular plates. These plates are just like the plates used regularly except the growth medium being used has more nutrients for the Arthrobacter to grow.

Next Steps:

If there are plaques, then the experiment will proceed with picking a plaque. If there is contamination or no plaques, new methods will be used to find a phage.