I created 4 Winogradsky columns to see if I could show some of the various ways that microbes can survive, including in both aerobic (with oxygen) and anaerobic (without oxygen) conditions.
Column CA: In the mud in this column I placed shredded filter paper (carbon or cellulose source), magnesium sulfate (sulfur source), baking soda (sodium bicarbonate) and one crushed multivitamin pill. This column was placed in my kitchen window.
Column CB: This column was created the same as column CA, however it was enclosed in a box and kept away from light. The intent of this mixture was to provide an environment where chemosynthetic organisms could thrive without light.
Column WA: This column I mixed mud with cut grass (carbon/cellulose source) and the magnesium sulfate. Column WA was placed in the window next to column CA.
Column WB: This column was mixed the same as column WA, however it was placed in the box and kept out of the light with column CB.
After 52 days, I have seen column CA go through several stages of apparent growth. The water column at the surface went completely black for about 1 week and now has become clear again. The mud has remained almost totally black throughout, though for a few weeks there was some white areas within the upper level of the mud, closer to the water column. A thin film has remained on the surface of the mud throughout. The film was originally a whitish/greenish color and now is a thicker film that is red in color. There are red particles floating in the water column. The column has an rotten-egg like odor.
Column WA has gone through more changes. At one point the water column had taken on a foggy redish hue, but now the water is clear again. There is now a thick red film at the surface and thick red layers in the mud on the side facing the window. This column does not have a strong odor.
There has been very little change in either columns’ WB or CB. Neither column has a distinguishable smell. Both columns did go through some color change in the water column, however this was not as dark black as column WA went through. Both columns have maintained a thin film on the surface of the mud. Column WB has a thicker, redder film.
I found it very exciting to look at samples in a microscope and would recommend this part to any classroom experiment. It would be even better to have an opportunity to try to identify the microbes through isolation and gram staining.
Altogether, I think that the columns will take several more months before they can show the type of nutrient cycling and photosynthetic vs. chemosynthetic growth that the columns are known for.
Here is a photo of the surface of column WA this week:
Here are two photos of the side that has been exposed to light:
Here is a photo of the side that has been opposite the window:
In retrospect, I would have liked to use a different protocol, a contorol, and different carbon sources. I also notice that neither protocol called for a nitrogen source, so you can not follow the nitrogen cycle and it may have limited the types of bacteria that thrived in my columns. I have since found two sites that I would probably use with a class & that have a much better description of the protocol to use with students: 1. http://www.kabt.org/wp-content/uploads/2008/01/winogradsky-for-kabt-web-site.pdf
2. http://www.sciencebuddies.org/science-fair-projects/project_ideas/Geo_p038.shtml
For perspective, I also liked this site: http://steel.ced.berkeley.edu/research/hidden_ecologies/?p=31 from the Exploratorium’s Invisible Dynamics Project. This will be something to follow over time though because they’ve just got started.
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