Rationale:

To wash soil sample 4 and enrich it using Arthrobacter, to determine the pH of the sample, and to also set up the experiment to determine the soil components

Procedure:

First, 2 mL of the soil sample was taken out and transferred to a new vial. 10 mL of LB broth was added to the vial and vortexed for 15 minutes. Then, the vial was weighed and placed in the centrifuge for 10 minutes. While the sample is in the centrifuge, prepare the soil composition experiment by adding 4 mL into a tube along with 8 mL of water. Vortex for 30 seconds then add 3 drops of soil dispersion liquid and set aside. After 10 minutes, the vial was taken out and the supernatant was separated from the rest of the contents. Using a syringe and 0.22 µm filter, the supernatant was filtered to become the lysate. 0.5 mL of Arthrobacter was then poured into the lysate. Finally, the pH of the soil was taken using some of the soil sample, water, and pH paper. Water was filled to the top and shaken for 45 seconds. After it was left alone for 2 minutes, the pH was taken using the pH paper.

Results and Analysis:

On the right, the control with little amounts of contamination. On the left, the plaque assay with a negative result.

When the LB broth is used, it is clearly uncontaminated; however, the next class there was contamination.

The contamination may have been due to the contaminated LB broth.

The soil was a mostly a mixture of clay and soil.

pH of soil sample: 5.7

Mass of Soil Sample and LB Broth: 18.54 g

Mass after adding water drops: 19.43 g

Total amount of lysate: below 5 mL

Conclusion:

In order to wash the soil sample, 2 mL of soil and 10 mL of LB broth was combined together then vortexed for 15 minutes. After the 15 minutes, the vial was weighed then placed in the centrifuge. While the vial was in the centrifuge for 10 minutes, a method used to determine the soil composition was made. The method called for 4 mL of soil with 8 mL of water and an addition of 3 drops of soil dispersion liquid. After centrifuged, the supernatant was separated from the rest and then filtered using a syringe and filter. Then, the pH of the soil was taken.

Future Plans:

Next time, the lysate will be filtered and will be used to prepare a plaque assay. Also, a plaque assay will be made using the previous lysate (soil sample 3).