Sammy and I decided to collect soil near the Ginkgo tree next to the Humanities building. On the day we collected the habitat was cool and dry. However, on a sunnier day the soil could definitely experience direct sunlight. The Ginkgo tree is fairly isolated from other plants. Two sidewalks separate it from the bushes along the sides of Humanities and Munger.
The top layer of soil was very dry but when we dug a few
inches deeper into the ground the soil was visibly moister. There were
definitely rhizospheres in the soil as we collected. Before digging, we put on
latex gloves and wiped down our trowel and scoopula and laid them on clean
paper towels. After digging into the soil with the trowel we used the scoopula
to collect 15ml of soil. Once we had our soil we headed back into the lab and weighed
out 0.5g or our sample and mixed it with 50ml of sterile water. We then set
this mixture aside and allowed the larger soil particles to settle at the
bottom of the tube.
While the soil in out tube settled we labeled five sterile
microfuge tubes and five tryptic soy agar plates with 10^-3 through 10^-7. We
then pipetted 0.9ml of sterile water into each microfuge tube. Once most of the
soil settled to the bottom of the tube we pipetted 1ml of the mixture into the
microfuge tube labeled 10^-3 and mixed well. We then transferred 0.1ml from the
10^-3 microfuge tube to the tube labeled 10^-4 and mixed well. We continued
this serial dilution ending with the tube labeled 10^-7.
After all the dilutions were prepared we transferred 0.1ml
of each dilution on to the corresponding agar plate and spread the cells evenly
across the plate. Lastly, we spread
0.1ml of the 10^-4 dilution onto a plate of Rose-Bengal agar plate. We then
inverted the plates and left them to incubate at room temperature for about a
week.
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| Agar plates before incubation (2/10/15) |
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| Agar plates after incubation (2/16/15) |
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