Purpose

The purpose of this lab was to begin a new experiment that would give a more in depth reason as to why ciliates are important in the soil system as well as to the world as a whole. We have already looked at how microplastics influence a specific ciliate, Tetrahymena, but now we can see really how they are present in the soil by finding them in our wild soil samples, and their place in the soil food chain. These general points were our purpose for today’s lab as we embark on a new experiment.

Procedure

Before starting experiment~

1. Grab the soil plates that you collected for lab #5.
2. Perform the non-flooded plate procedure. Add water until the soil is saturated but not flooded.
3. Let sit for approximately 30 hours.

Once in lab~

1. Reclaim your petri dish and pull up the numbers you recorded in lab #5 regarding dish weight, soil plus dish weight, and soil weight. These recordings are your ‘wet’ soil data.
2. In a chart, enter these numbers as well as the numbers from the ‘dry’ soil that were recorded before putting the water into the dish. (For the following steps, I will be using practice numbers because my dish was not weighed prior to the water being added.) Make sure you use the correct number for whether you weighed the dish with the lid on or off. Table 1.
3. Calculate the percent water. Use the equation: [(wet soil – dry soil) / wet soil] x 100. My numbers are recorded in Table 2.
4. Now centrifuge 300μl of liquid from the dish. Allow the centrifuge to run for at least 10 seconds and also make sure the dish is balanced by having to samples go simultaneously 180 degrees apart.
5. Pipette 20 μl of the centrifuged liquid and place on top of the petri dish lid.
6. Place a strip of pH paper (pH 5-9) directly on top of the drop and allow to sit for at least 15 seconds.
7. Using the pH scale provided with the pH paper, calculate the pH of the soil extract, and record. Table 2.
8. Now proceed to observe the soil underneath the dissecting scope and compound scope. To have the best view, grab a pipette and pull off some of the water and shift the dirt around so you have a clear view to the bottom of the petri dish. Break up any obvious clumps in the soil.
9. Place the dish on the stage of the dissecting scope and begin to search for any ciliates. This will be challenging because the dissecting scope has a low magnification, but search nonetheless.
10. Once you are sure you have thoroughly searched the dish, pipette 10 μl of the liquid from the top of the dish onto a concavity slide. Try to not pull up any soil, but if you do, no worries.
11. Start at the 4x magnification. Once you spot a ciliate, use a pipette to distribute the drop into more small drops of liquid. This process is to corner the ciliates into a smaller area in order to use a higher magnification.
12. Once you have divided the liquid into smaller drops, add a syrup-like substance to the drops to slow down the ciliates, and place a cover slip on top of the slide.
13. Observe under the compound microscope, take photos, and record findings.Table 3.

Data

Table 1~ Weights

Table 2~ % Water & pH

Table 3~ Found Ciliates

Storage

• The petri-dishes were returned to the fume hood area for storage.
• Slides and covers were washed and placed on a paper towel to dry.
• The pop-lid container (the tube used in the centrifuge) containing the liquid from the dish was thrown away after the contents were drained.
• The pH paper was thrown away; the hand-held pH measure was stored in its box and placed at the end of the table.
• Microscopes were covered and unplugged.
• Any paper towels, slide cleaning paper, and disposable pipettes were all thrown away.

Conclusion

As we wrap up our Tetrahymena experiment, we begin our new experiment regarding wild ciliates and their place in the soil ecosystem. This is important because this soil experiment gives us the background information for why our Tetrahymena experiment is important and relevant to all people. Today’s specific lab, showed us that ciliates do exist in everyday life and we proved this by finding ciliates in the soil we collected. As we performed the necessary steps to observe the ciliates, we were able to personally ‘discover’ our ciliates. This experiment allowed us to combine all of our laboratory skills and gave us a great insight into the relevancy of ciliates.