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Life Science: EcoColumn

Basically, I'm a Fungi

Pronounced by some as “fun guy,” the fungi are part of the mostly microbial world of decomposers. Along with bacteria, fungi are responsible for the decay of dead things that would otherwise pile up around us. Basically, I’m a Fungi makes these organisms readily observable as cultures that grow on special materials — Petri plates that contain prepared media that act as a food source. This particular medium contains a relatively high amount of sugar, which favors fungi over bacterial cultures.

Two types of fungi may grow in your plates. Yeasts tend to grow into smooth, spreading circular colonies, while most molds will eventually develop into fuzzy growths. It’s not important that you identify which is which, just that you observe and appreciate the diversity and abundance of these decay organisms, which can be found on almost every surface.

Materials Needed

Instructions

  1. When your Petri plates arrive, be sure not to open the lids. You’ll inadvertently introduce microbes if you do.
  2. To conserve media and make side-by-side comparisons, use a permanent marker to divide each plate into thirds on both the lid and the bottom.
  3. Select surfaces to be tested for the presence of fungi. A good variety will include soil, water, air (the inner surface of the bottle), plants, and animals.
  4. In each of the three Petri plates, write the name of one of the surfaces that you’re testing at the outer edge of the bottom side of the plate (the top may move around). Consider making one of the sections a “control,” which you do not disturb. The control can be used to make comparisons.
  5. Using a sterile swab for each surface, gently swipe the surface. Take care not to pick up debris.
  6. Open the appropriate Petri plate. Start at the outer edge of the appropriate section and make a streak in an “S” shape. Be sure not to press too hard and to keep your streak within section boundaries.
  7. Replace the lid and tape it closed.
  8. Turn each plate upside-down to avoid a “rain” of condensation from the lid as the colonies grow.
  9. Incubate in a warm place.
  10. Observe microbial growth in your plates over a two-week study period and record what occurs on your “Basically, I’m a Fungi” Data Sheet.

Note: It is safe to culture microbes in this way — they grow in a closed container and are types that are already present in the environment. To dispose of the plates, spray with disinfectant solution, seal, and throw away. The only thing to be careful about is opening the plate during your study — each time you do, you may introduce new microbes!

Activity Questions

Before you swab your plates:

  1. What are the distinguishing characteristics of fungi?
  2. Which surfaces do you think harbor these microbes?
  3. How do you think different surfaces might compare?

After your study period:

  1. What surfaces did you test for the presence of fungi?
  2. Describe the growth that resulted from testing these surfaces.
  3. How did different surfaces compare?
  4. Were you surprised by your results? Why?
  5. What can you conclude about fungal life in your EcoColumn?

SHARE YOUR RESULTS: Basically, I'm a Fungi

TRACK OUR PROGRESS: Basically, I'm a Fungi

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