What type of environment would
have the greatest number of ameoba?
If more decomposing material is
present in a microenvironment, then more bacteria will be present and consequently
Petri dishes containing a gel made from agar and
water (no added nutrients).
Containers and tools for collecting the soil samples.
Soil samples from six different microenvironments.
Sterile swabs and/or inoculating loops.
A culture of a suitable food bacterium,
microscope and/or steroscope
(optional equipment) flex cam and TV monitor
or computer hook up, digital camera
First we poured and labeled six sterile petri dishes
with 20 ml. of prepared agar that was nutrient deficient.
Next we selected six micro environments of varying
decomposition. The control was sand.
The five experimental sites were soil under pine needle dead fall,
soil around a decaying log, mud from the edge of a stream, soil around
knee of living tree, and soil under a decaying squirrel.
Next we inoculated each petri dish in the center
with a pea size sample of each of the 6 soil types using a scoopula.
Then using a sterile swab we carefully make a ring
one centimeter in diameter around the bit of soil. Between the soil
and the surrounding bacterial ring there was a bare agar surface.
Lastly we incubated the plates upright, at room temperature,
for 48 hours. Observations were recorded at intervals of 2 days,
4 days, and 7 days. Observations were qualitative in nature, using
the microscope, digital camera images, and written descriptions.
As a result of setting up part I, we questioned the
amount and kind of bacteria found in each of our soil samples.
We obtained petri dishes made with nutrient agar
containing cyclohexane (a fungicide), in order to isolate just bacteria.
We then made a series of dilutions resulting in 1g
soil /1000ml distilled water.
The soil dilutions were then streaked onto the agar
plates and incubated for 72 hrs. at room temperature.
Qualitative observations were made and recorded.
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