Bacterial Diversity
The Examination of Bacterial
Colonies in Selected
Environments
By Lara Hartman and Daniel Arbeider
Purpose
Explore the bacterial diversity found in:






Air
Raw Chicken
Soil
Pond Water
Washed & Unwashed Hands
Library Table
Establish which environment supports the
greatest diversity of bacteria.
Compare the data generated to determine if
our hypothesis is supported.
Hypothesis
Pond water will contain the greatest diversity
of bacteria when compared to other
observed environments.
Methods
Label each Petri dish according to the environment tested.
To isolate bacterial colonies from the soil, pond water, chicken,
and the PSU library table the “Streak Plate method” was used.
For the air sample the lid will be removed for the duration of the
experiment.
For washed and unwashed hands, a thumb will be pressed on
the surface of the agar.
Incubate all plates for 1 week at 22 C.
Air
Size
Shape
Margin
Surface
Color
A
15 mm
Irregular
Lobate
Smooth
Milk-White
B
5 mm
Round
Smooth
Concentric
Pale Yellow
C
6 mm
Round
Curled
Concentric
White
D
6 mm
Round
Smooth
Smooth
Off-White
E
14 mm
Irregular
Lobate
Contoured
Mustard
Raw Chicken
Size
Shape
Margin
Surface
Color
A
1 mm
Punctiform
Lobate
Wrinkled
Off-White
B
7 mm
Irregular
Lobate
Contoured
Clear
Soil
Size
Shape
Margin
Surface
Color
A
6 mm
Irregular
Lobate
Smooth
Off-White
B
7 mm
Irregular
Fungus
Filamentous
Contoured
White
C
30 mm
Irregular
Lobate
Contoured
Clear
Pond Water
Size
Shape
Margin
Surface
Color
A
3 mm
Round
Smooth
Smooth
Off-White
B
10 mm
Irregular
Lobate
Contoured
Off-White
Washed and Unwashed Hands
Size
Shape
Margin
Surface
Color
A
59 mm
Irregular
Wavy
Smooth
Off-White
B
7 mm
Irregular
Filamentous
Contoured
White
C
13 mm
Irregular
Lobate
Smooth
White
Library Table
Size
Shape
Margin
Surface
Color
A
15mm
Irregular
Lobate
Smooth
White
B
6 mm
Round
Wavy
Concentric
Yellow
C
11 mm
Round
Smooth
Concentric
Yellow
Fungus
D
E
3 mm
Round
Smooth
Smooth
Orange
Data Interpretation
After one week, observations were made of the colony
morphology of the different bacterial species in each
environment.
Charts were constructed to compare the diversity and
abundance of bacteria in the various environments.
Our data clearly showed that the hypothesis under
investigation was not supported; however, it is reasoned
that the pond water sample was not the best
representation of aquatic life. In our next experiment all
layers, top – middle-bottom, will be analyzed.
Escherichia coli
Role:
Produces Vitamin K in the
intestinal tract.
Pathogenic effects:
Human urinary tract
infections
Diarrhea
Pneumonia (linked)
Meningitis (linked)
E.coli
How E.coli infects:
E.coli and how it infects – Part 1
E.coli and how it infects – Part 2
E.coli and how it infects – Part 3
Treatments:
Antibiotics are not recommended. (May cause shock)
Studies:
Antibiotic treatment increases risk of urinary tract infections from
8% (no treatment) to 56% (antibiotic treatment).
E.coli develops antibiotic resistance quickly.
E.coli
Control
Antibiotic
Dose
Zone of Inhibition
Sensitivity
1
Steptomycin
10 mg
5 mm
Sensitive
2
Penicillin
10 mg
0 mm
Not Sensitive
3
Erythromycin
15 mg
3 mm
Sensitive
4
Tetracyclin
30 mg
7 mm
Sensitive
5
Kanamycin
30 mg
5 mm
Sensitive
6
Chloramphenicol
30 mg
12 mm
Very Sensitive
7
Nalidixic Acid
30 mg
11 mm
Very Sensitive
8
Novobiacin
30 mg
0 mm
Not Sensitive
0 mm
Not Sensitive
Sources
•
Carter Brown, M.E., and J.G. Morgan. Investigating Biology: A Laboratory
Manual for Biology. San Francisco: Benjamin Cummings, 2002
•
Dennis Liu, Ph.D., and B. Brett Finlay, Ph.D. Enteropathogenic E. coli Infection
Mechanism. Retrieved November 2 2004, from
http://www.savetheantibiotic.com/public_html/0_Educators/bacteria_mov1.html
•
Craig S. Wong, Srdjan Jelacic, Rebecca L. Habeeb, Sandra L. Watkins, Phillip I.
Tarr; Early Release article, The New England Journal of Medicine; May 23, 2000.
Retreived November 2, 2004, from
http://www.coloradohealthsite.org/CHNReports/antibioticsandecoli.html
.