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Using A Winogradsky Column to Analyze Microbial Communities

Frances Vandervoort
1991 Woodrow Wilson Biology Institute


Objectives

In this investigation, students will use easily obtained materials to study ecological succession in a microbiological community. The investigation is appropriate for a variety of age groups. Elementary students will be fascinated by the changes occurring over time in their bottles. First and second year high school students can do microscopic sampling of their communities that will introduce them to diversity among microorganisms. Upper level high school students can use sophisticated sampling techniques of microorganisms and chemicals within the columns for both quantitative and qualitative studies.

Background

Bacteria, ubiquitous in nature, are responsible for the evolution of the Earth's atmosphere. Photosynthesis occurred first in anaerobic bacteria, which adapted to the Earth's ancient environment by using sunlight, water, and readily available carbon to produce carbohydrates and free oxygen. At least four groups of photosynthetic bacteria abound on Earth today; the green sulfur, the purple sulfur, the purple nonsulfur bacteria, and the brownish nonsulfur Heliobacterium (Sagan and Margulis, 1988). It is possible to establish a culture of photosynthetic bacteria in a "Winogradsky column", a device based on a more elaborate one made by Russian microbiologist Sergei N. Winogradsky, who lived in Russia and France the early part of this century.

Materials

  • Clear plastic 1 liter bottle
  • Mud and sand from outdoor source, especially from a marshy area where colorful mats and scums of microorganisms can be found. Saltwater or freshwater marshes can be used.
  • Water from outdoor source, such as a stream, pond, lake, or puddle. Again, use either fresh water or salt water.
  • Calcium sulfate of hard boiled egg yolk (as a sulfur source)
  • Shredded paper (a piece of newsprint about 100 cm2) or cellulose fibers (as a carbon source)

Procedure

  1. Mix the sand or mud with about a tablespoonful of egg yolk or calcium sulfate. Add a few shredded cellulose fibers or paper. Layer the sand and mud in the plastic bottle. It is easier to fill the bottle if you first remove the narrow neck of the bottle by carefully cutting through the plastic with a single-edged razor blade or paper cutter.
  2. Pour the water you have collected over the top of the sand-mud mixture so that there is a small amount of unabsorbed water on top.
  3. Cover the bottle with plastic film secured by a rubber band, place it in a sunny window, and a rich culture of photosynthetic bacteria will develop within a few weeks. A similar column kept in the dark will also develop a bacterial population, but the bacteria will not be photosynthetic.
  4. Watch the columns over several months. Color changes indicate that ecological succession is taking place.

Discussion Questions

  1. Describe the changes you see taking place over a period of several months. Record observations every one to two weeks.
  2. Using a long pipette, take samples from various depths within your column and place them on a microscope slide. Examine and draw those that you see. Use a key to microorganisms to identify all you can.
  3. How is a Winogradsky column similar to the bottom of a pond? How is it different?

References

Pigage, Helen K. "The Winogradsky Column: A Miniature Pond Bottom." American Biology Teacher (47/4), April, 1985. Pp. 239-240.

Sagan, Dorion, and Margulis, Lynn. Garden of Microbial Delights. Boston: Harcourt, Brace, Jovanovich. 1988.


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