Rationale

Today’s goal is to wash Soil Sample B using a new technique to produce a direct and enriched isolation. We will also collect metadata on the soil sample, consisting of pH and percent water composition.

Procedure

1. Use the aseptic technique to clean the area. With gloves on, spray CiDecon on the lab table and wipe dry. Then wipe 70% EtOH on the surface and let the excess evaporate.
2. Place 2 mLs of the Soil Sample B into a 15 mL conical vial. Label the tube “EAG 9/10/18 Soil Sample B Isolation.”
3. Add 10 mLs of LB broth to the vial and place the vial on the vortex on setting 10 for 10 minutes to mix.
4. Mass the 15 mL conical vial and prepare to centrifuge by finding another vial with a similar mass.
5. Place “EAG 9/10/18 Soil Sample B Isolation” into the centrifuge and spin for 5 minutes at 10,000 g.
6. While the 15 mL conical vial is spinning, begin conducting percent water metadata on Soil Sample B. Weigh the mass of the weigh boat and then add some of Soil Sample B to the weigh boat and mass again.
7. Label the weigh boat “EAG 9/10/18 %H2O Metadata” and place into the vacuum hood inside the lab. Let the weigh boat containing the sample sit for 48 hours.
8. After the 15 mL conical vial labeled “EAG 9/10/18 Soil Sample B Isolation” has finished spinning, use a 2 mL syringe and a 0.22 μm filter attached to the end of the syringe to filter all of the supernatant available into another 50 mL conical tube labeled “EAG 9/10/18 Enriched Isolation.” (note: only 8.5 mLs of filtered enriched solution was produced, therefore no direct solution was made.)
9. Add 0.5 mLs of Arthrobacter to the 50 mL conical vial and incubate the tube for 48 hours at 28 degrees Celsius.
10. Next, measure the pH of Soil Sample B by placing a small amount of soil into a pH vial. Fill the rest of the vial with DI water. Shake vigorously for 10 seconds. Let the vial sit for 2 minutes.
11. Place a 1 inch strip of pH paper into the vial for 45 seconds. Use the color of the pH paper to determine the pH of the soil sample.

Observations

• The mass of the 15 mL conical vial before being centrifuged is 19.219 g.
• The mass of the weigh boat is 2.39 g and the mass of the soil sample and weigh boat is 10.08 g.
• The pH of the soil is 5.5.
• The supernatant produced after centrifugation resembled a clear yet slightly yellow tint.

Conclusion and Next Steps

The sand, silt, and clay composition of Soil Sample B was not determined due to a lack of falcon tubes present. The composition metadata will be observed during the next lab. We will also conduct a spot test in hopes of producing plaques.