Lab 6 – Experiment 1: Winogradsky Column
Sergei Winogradsky (1856-1953) was a Russian microbiologist who was one of the first scientists to study mixed populations of bacteria with differing metabolic abilities. In a Winogradsky column, two
distinct gradients form in opposite directions: oxygen is high at the top of the column and non-existent at the bottom while hydrogen sulfide is high at bottom and non-existent at the top. Additionally, light
facilitates the growth of aerobic photosynthetic bacteria. These generated gradients allow for growth of a large variety of bacteria that reproduce the biogeochemical cycles on which life depends.
• 2 Full pages of shredded newspaper
• (2) 5 g. Bags of calcium carbonate (chalk)
• (2) 5 g. Bags of calcium sulfate
• Paint stirrer
• (2) Rubber bands
• Permanent marker
• 1 pair of gloves
• 4 Large plastic bags
• 250 mL Beaker
• *2 Clean, clear 2 L plastic bottles with the top cut off
• *8 – 10 C. of dirt or mud (pond, lake, city park, yard, etc.)
• *8 – 10 C. of water (preferably collected from the same location as the dirt/mud); tap water will also suffice).
• *Light source (south facing window or lamp with no more than a 60 W bulb)
• *Large bowl
*You must provide
Field Trip – Water and Soil Sample Collection
1. Identify a location that has water and soil available for collecting; and, which you believe has features abundant micro-organismic, plant or animal life. Keep in mind that you will need 8 – 10 cups of
water and 8 – 10 cups of soil.
2. Use graph paper to sketch a diagram of where you will collect your water and soil samples from. Be sure to label the graph with descriptive information, and indicate any other critical information
that might affect the water quality. For example:
• Has it recently flooded?
• Is the area experiencing a drought?
• Is there snow or ice present?
• What is the temperature?
• Is the surrounding animal/marine life steady/predictable?
• What kind of animals/plants are local to the area?
• Is it humid out?
This diagram is called a Field Report and will become useful should you need to re-assess the original environment.
3. Label each plastic bag with the location name and the collection date.
4. Go into “the field” to obtain your samples. To do this:
• Pack up your plastic bags, gloves, ruler, 250 mL Beaker, and a printed copy of this procedure.
• Water sample collection: (you can collect your soil sample first; refer to the bottom half of this section for soil sample collection methods).
NOTE: Some collectors may wish to wade into the water to obtain their water sample. As a general rule of thumb, water collectors should NOT wade into flowing water if the water depth (in feet) x the water
velocity (in feet per second) is greater than or equal to 10. If you have any hesitations regarding water-safety, do NOT enter the water!
i. Completely submerge the 250 mL beaker in the water body, being
careful to avoid collecting as much sediment and debris as possible.
ii. Transfer the water from the beaker into one of the plastic bags designated for your water sample. Repeat this process 5 times for
each bag (a total of 10 times).
iii. Seal the bags tightly and store them away or set aside until you
leave the area.
• Collect your soil sample. It is ideal to use the same environment that the
water sample came from. However, you can move to a new location if necessary.
i. Remove any surface debris (plant residues/leaves/branches/ thatch/etc.) from the soil site.
ii. Insert your trowel into the soil and observe the following depth guidelines depending on the soil environment:
• Sample the soil down about 6 – 8 in. deep if collecting from a garden/ flower bed zone (use your ruler to approximate the depth).
• Sample the soil down about 3 in. deep if collecting from a turf zone.
• Sample the soil down about 8 – 12 in. deep if collecting from a root zone.
• Collect in between crop rows if collecting from a fertilizer band.
• Try to sample dark, light, limed, and unlimed soil areas separately.
iii. Scoop up the soil, and transfer it into one of the plastic bags designated for the soil. The trowel in your lab kit can contain 1/3 of a cup. Therefore, you will need to repeat this process 12 -15 times
for each plastic bag (a total of 24 – 30 times)
iv. Try to return back to your “lab” without changing the structure of the soil composition. Natural clumps, rocks, etc. should be maintained to get a more authentic understanding of the soil porosity
and biochemical habitat.
5. Put approximately 946 mL (4 C.) of the dirt/mud into a large bowl or bucket, add 1 bag (5 g.) of the calcium carbonate, and 1 bag (5 g.) of the calcium sulfate to the mixture.
Note: There are 236 mL in one cup.
6. Add enough of the water you collected to make a thick, but somewhat fluid, mixture. This should require approximately 946 mL (4 C.).
7. Add approximately 1/2 of the shredded newspaper to the bowl and mix again.
8. Transfer this mixture to the soda bottle and tap the bottle on the ground or other hard surface to pack the mixture tightly to the bottom. It is important that no air pockets or bubbles should remain in
9. Use a paint stirrer or handle of a long spoon to further pack the mud and remove any air.
10. Add approximately 236 mL (1 C.) of the remaining (unmodified) dirt/mud on top of the previous layer and tap again to pack it down.
11. Add water to a depth of approximately 1 in. above the last layer and make a small mark with a permanent marker on the 2 L bottle at the top of the water level.
12. Let the column sit undisturbed for 30 mins. and monitor the depth of the water. If the water level rises, remove some to return to the original level. If the water level decreases, add more to return to
the original level. There should be approximately 1 in. of air space above the water.
13. Cover the top with Parafilm™ and secure with a rubber band.
14. Repeat the Steps 5 – 13 to create a second Winogradsky column.
15. Incubate the columns for 6 – 10 weeks at room temperature. Place one column near a south-facing window to receive indirect sunlight, or approximately 2 ft. away from a lamp with a 40 – 60 W.
bulb. Place the second column in a dark location (without natural or artificial light available). Remember to rotate the columns 180° 1 time per week.
16. Observe the column every 7 days and record your observations in Table 1.
Table 1: Winogradsky Column Observations
Week # Observations (Colors, Layers, Column Location) of Column in Light Observations (Colors, Layers, Column Location) of Column in Dark
1. Do ecosystems change over time? If so, what causes those changes to occur?
2. How did your results vary between the two columns? Why do you think their responses were different? Be specific.
3. Where does carbon come from in a Winogradsky column?
4. What is carbon important?
5. What purpose does calcium sulfate serve in the Winogradsky column?
6. How is photosynthesis different between cyanobacteria (growing at the top of the column and green and purple sulfur bacteria (growing near the bottom 1/3 of the column)?
7. Identify three critical factors (abiotic or biotic) required for primary succession to occur.
8. Define two reasons why ecological succession progresses from populations with low diversity to populations with high diversity.
9. Highly diverse ecosystems are often regarded as a more “healthy” ecosystem. Explain why.
10. How does ecological succession demonstrate the evolutionary process of “survivial of the fittest”?
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