The Winogradsky Column: Understanding the
Microbiology of a Wetland
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II.
III.
Question: How do various pollutants affect bacterial and algal colonies in a
Winogradsky column?
Hypothesis:
Materials:
Large graduated cylinder
Mud or sediment
Rain or pond water
Paper
CaCo3
CaSO4
Iron nail or screw
Plastic wrap
Rubber band
Microscope slides
Light source
http://www.lyon.edu/webdata/users/dthomas/BIO100H/lab/winogradsky.html
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Methods:
a. Shred the paper and place in the bottom of the graduated cylinder
b. Mix mud and water in equal amounts to create a slurry. Add one spoonful
of each CaCo3 and CaSo4. Add your designated pollutant. Pack into
graduated cylinder until 2/3 full. Pack to eliminate air bubbles. Why?
c. Add iron nail or screw.
d. Top off the column with pond or rain water until ¾ full. Allow space for
air!
e. Place two microscope slide vertically in your column with a small section
exposed from the soil. This will allow bacterial samples to collect that
you can remove and observe.
f. Cover the column with plastic wrap and secure with a rubber band.
g. Place the column in front of a light source.
h. Observe the column once a week and record appearance of colored areas.
Aerobic mud will be brownish and aerobic mud will be black. Examine
the paper for signs of decomposition
i. Note if bacteria is growing in aerobic areas and if algae is growing in
anaerobic areas.
Data Collection:
a. In your lab notebook, you should record your observations weekly. A
sketch or digital photograph will enhance your observations.
Analysis
a. At the end of the allotted time, you should write a brief analysis of your
column. Examine other groups columns as well. What is happening in
your tube?
Conclusions
KEY TO POTENTIAL OBSERVATIONS
Aerobic color
Green
eukaryal algae or cyanobacteria
Red/Brown
cyanobacteria or thiobacilli
Red/Purple
purple non-sulfur bacteria
White
sulfur oxidizing bacteria
Anaerobic color
Red/Purple
Green
Black
purple sulfur bacteria
green sulfur bacteria
sulfate reducers
Gas in the water column is probably from O2 from oxygenic photosynthesis
Gas in the aerobic zone is probably from CO2 from respiration
Gas in the anaerobic zone is probably CH4 from methanogenesis
Tracks in the upper layers of the sediment are from by polychaete worms
Small specks swimming in the water column are crustaceans
KEY EQUATIONS
Plant photosynthesis:
6CO2 + 6H2O  C6H12O6 + 6O2
Bacterial anaerobic photosynthesis:
6CO2 + 6H2S  C6H12O6 + 6S
Cellular respiration:
C6H12O6 + 6O2  6CO2 + 6H2O
Oxidation of Iron:
H2S + Fe  FeS + H2
MORE INFORMATION ON THE WINOGRADSKY COLUMN
Initially oxygen diffused downward from the surface of the water (the air trapped in the
top of the tube). The breakdown of the cellulose in paper (carbon) and hydrogen sulfide
is achieved via fermentation. The products of these reactions are released and move up
the column. Oxygen is very limited at the bottom of the column due to slow diffusion
rates. Bacteria that are present at the bottom of the column are mainly responsible for the
decomposition of the cellulose found in the shredded paper. The distribution of oxygen
and sulfides creates a gradient within the column that will allow different organisms to
thrive at different depths. Algae may be present at the top of the column and produce
oxygen. In this area, organisms such as protozoans may be found.
Because this column represents a closed system (no additional nutrients are added), we
can see nutrient cycling. Photosynthesis and respiration are recycling carbon, hydrogen,
nitrogen, sulfur, and oxygen.
http://www.personal.psu.edu/faculty/j/e/jel5/biofilms/winogradsky.html
http://helios.bto.ed.ac.uk/bto/microbes/winograd.htm