Goal

Some bacteria can grown without any organic compound, except CO2. These autotrophs can for example get their energy from sulphur.

Materials

  • 100 mL of THt
  • 3 50 mL erlenmeyer flasks
  • Soil
  • pH test strips

Method

  1. Prepare 2 Erlenmeyer flasks by transfering 25 mL THt into each.
  2. Add some soil to one of the Erlenmeyer flasks.
  3. Save the other Erlenmeyer as negative sterile control.
  4. Clearly label the flasks: name, date & content.
  5. Incubate the flasks at 30° C on a shaker.
  6. Inspect the flasks every day or two.
  7. As soon as (most likely after one week) a small film can be observed on the surface of the medium, transfer a small amount into a fresh Erlenmeyer flask with 25 mL medium.
  8. Incubate this flask again at 30° C on a shaker.
  9. Check for color change and measure the pH.

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