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Introduction
In many schools across the country in biology and life science classes, the topic of microbiology is often relegated to a short discussion of diseases and viewing
bacteria under the microscope. While some instructors are able to grow cultures so that students see different species of bacteria, rarely is it show how they can interact with each other in the
environment. Students often have the misconception of bacteria as static, immovable organisms. The Winogradsky Column investigation can be used as a tool to understand microbial life. It is an
excellent way to understand the growth of microbial communities and to show succession as the column develops. In addition, it helps many students see the difference between aerobic and anaerobic communities.
However, the investigation often stops there once the column develops since very few teachers understand the complexity that lies within the depths of the ecosystem that has developed.
The Winogradsky Column was first used in the 1880’s by Sergei Winogradsky (1856-1953), a Russian microbiologist, to study the complex interactions between environmental conditions and microbial activities
and the role of soil enrichment in the isolation of pure bacterial cultures. Many microbiologists of the time, such as Louis Pasteur and Robert Koch isolated cultures for study, but Winogradsky’s work was the first
to study mixed environments of microorganisms.
The column is not a natural environment. All of the organisms are mixed during the preparation and it is merely to study environments that develop over time. When it is sealed and exposed to light, a
succession of microbes will develop according to the concentrations of oxygen, nutrients and light available. Depending on the various concentrations of nutrients and the type of soils used, a variety of bacteria
will appear over time. However, it is an excellent model of microbial ecology. Each organism is dependent on the other to set the conditions for development and the entire column is run on the energy of light.
The Winogradsky Column is a classic demonstration of the metabolic diversity of prokaryotes.
Methodology
Building the Basic Column
- A glass or plastic container minimally15 cm in height and 5 cm in diameter is ideal but any size container will do. Plastic bottles are ideal because they can be manipulated easily to allow for extraction
of species of culturing. If possible, the container’s sides should also be smooth to make observing the bacterial growth easier. As well, very tall and wide containers take longer to grow and are more
difficult from which to extract bacteria.
- Clear plastic film and a rubber band
- A long wooden dowel
- Cellulose source--Shredded paper, grass, leaves, lettuce, sawdust or wood chips
- Sulfur source--calcium sulfate, magnesium sulfate, egg yolk. This should be added to be about 1-2% approximately of the weight.
- Carbon dioxide source(optional)--calcium carbonate – 1-2%. Both of the previous sources can be approximate
- A selection of soils--pond mud, river mud, saturated soil
- Water from the source of the mud
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