Microbial Ecology:

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Microbial Ecology

• An Analysis of Soil

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Purpose

• To collect soil from a grassy area and a flower
  bed, and to compare the types and quantities of
  microorganisms that grew from each, using two
  different media

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Materials

• Soil from grass
• Soil from flower bed
• Tryptic Soy Agar (TSA)
• Sabouraud Dextrose Agar (SAB)
• Plastic petri dishes
• Sterile water
• Inoculation loop
• Sterile cotton applicators
• Pipettes

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Procedure

• One sample each of soil from both a flower bed
  and a patch of grass was collected weekly.
• One gram of each was diluted in sterile water to
  solutions of 1001 and 10001.
• The solutions were then transferred to four TSA
  and four SAB plates according to the following
  methods 1001 streak for isolation 1001
  swab in S-pattern 10001 swab in
  S-pattern 10001 swirl of solution
• The plates were incubated for one day at 37 C
  and then left at room temperature for another
  day.
• A count of the bacterial and fungal species was
  then taken and analyzed.

5
Results

• Type of agar Overall, the microorganisms
  grew in larger quantities and with greater
  diversity on the TSA plates than on the SAB
  plates.

TSA
SAB
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Type of and amount of growth on the 100 1
isolation platesindicates variation according
to type of agar
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• Type of soil Overall, the soil from the
  grass contained larger quantities of the
  predominant bacteria than did the soil from the
  flower bed. However, the soil from the flower
  bed often contained larger quantities of fungi
  and more diversity in all of the species than did
  that from the grass.

grass
flower
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Type of and amount of growth on 10001 swirl
plateindicates variation according to type of
soil
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Dendogramindicates the dissimilarities between
the different soil types and the different types
of agar
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Type of and amount of growth on 10001 swirl SAB
plateindicates lack of change in growth over
time
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Conclusion

• There was a difference in the type of and amount
  of growth of the microorganisms when comparing
  the soil samples of the grass and flower bed.
• There was a difference in the type of and amount
  of growth of the microorganisms when comparing
  the two types of agar.
• There was no overall change in the amount of or
  type of growth as time passed and the weather got
  colder.

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By Melanie Walker Fall Semester 1997