Winogradsky Columns

Using Winogradsky Columns to Inspect Factors Affecting Bacterial Growth

By Nouf Alkhodari, Dalal AlJabr and Laila Fida

DAS-G12

Both Bacteria and Archaea are the most diverse and numerous organisms on Earth. For the first two billion years of Earth’s history, they were the only living beings on the planet. These microorganisms show remarkable diversity in metabolic mechanisms like oxygenic and anoxygenic photoautotrophs, chemoautotrophy, and photoheterotrophy, to name a few. They also play a very important role in cycling elements that make the planet habitable for all other types of organisms This experiment will include observing a sampling of microorganisms living in your local environment. It involves setting up Winogradsky columns (simple devices for constructing a stratified ecosystem that illustrate different types of microbial metabolism in a colorful way). In other words, a device for culturing a large diversity of microorganisms Invented in the 1880s by Sergei Winogradsky.

In inspecting the effects of additions such as Carbon, we note that Carbon dioxide is effective for extending the shelf-life of perishable foods by retarding bacterial growth. The overall effect of carbon dioxide is to increase both the lag phase and the generation time of spoilage microorganisms, however, the specific mechanism for the bacteriostatic effect is not known. As for Sulfur, Sulfur-reducing bacteria are microorganisms able to reduce elemental sulfur (S0) to hydrogen sulfide (H2S). These microbes use inorganic sulfur compounds as electron acceptors to sustain several activities such as respiration, conserving energy and growth, in absence of oxygen. Which are some of the results that'll be tested throughout this experiment.

Using Winogradsky columns to test the effects of Carbon and Sulfur on Sediment's microbial environment.

If both Carbon and Sulfur are added, then the sediment will endure changes indicating microbial growth, because Carbon helps produce nutrients and Sulfur can also help some bacteria conserve energy.

Independent: The component added

Dependent: Microbial growth

Control: Column without any added components

Constant: Amount of sediment in each column, amount of component added, temperature, pressure

Materials:

• 4 clear, 16-oz. plastic bottles.
• 1–4 disposable containers
• 1 trowel
• Permanent marker
• 4 small labels
• Water
• 1 bucket or container(large enough to hold 6–10 cups of sediment)
• Digital camera or cell-phone camera
• Large measuring cup or other container for measuring
• A carbon source, shredded newspaper; approximately 1 cup loosely packed
• 6–10 cups of sediment (mud)
• A sulfur source; raw egg yolk is best
• Large mixing spoon
• 1 funnel

1. Acquire a sediment source in your area.
2. Take 2 or 3 photographs of your sample site to illustrate the location where your sediment was collected.

3. Collect around 6 cups of sediment in the plastic bucket. The sample should be wet.

4. Label the four disposable containers: control, carbon, sulfur, and carbon+ sulfur. Add approximately 1.5 cups of the sediment sample that you collected to each of the disposable containers.

5. For the control container, skip to step 7.

6. For the other three (3) containers, follow the instructions below for each column:

a. For the “carbon” column: Add 1⁄2 cup of shredded newspaper (loosely packed) to the sediment and mix with a mixing spoon or trowel. (The newspaper contains cellulose, a source of carbon.)

b. For the “sulfur” column: Add the yolk of an egg (raw is best) to the sediment in the container labeled “sulfur” and mix with a mixing spoon or trowel. (The egg yolk is a source of calcium sulfate in the column.)

c. For the “carbon and sulfur” column: Add both nutrients as described in steps a and b.

7. Mix each of the samples thoroughly. Make sure to remove any large debris such as leaves, rocks, or sticks. Slowly mix in water (either water that you collected or tap water) until the mixture has the consistency of a milkshake.

8. Using a large spoon, slowly add approximately 1 cup of the mixture to the appropriately labeled plastic column (bottle). You may wish to use a funnel or an inverted, cut bottle top to add the sediment mixture . As you add the sample, tap the column on a counter or table to release any trapped air in the column.

9. Add water from the sediment collection source (or tap water) on top of the sediment until there is a 2-cm layer of water on the surface. (There should be air at the top of the column). Place the lid on each column and turn the lid a 1⁄2 turn. DO NOT tighten the lid! If you cut the bottle top, place plastic wrap over your column and hold the wrap in place with a rubber band.

10. Place all four columns in a well-lit space such as a windowsill.

11. Using a camera or phone, take a photograph of the columns to document changes throughout the experiment.

- Changes in smell were the most evident, especially at the carbon+sulfur sample

-Some slight changes in color as well as some changes in texture

As of right now, the hypothesis stands false, or more accurately, the hypothesis is still under testing! Due to time constraints, the changes were very slight. Hence, it needs more time to truly observe bacterial growth.

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