Do You Want Fries With Your Paper?

-Cellulose Digesters

Introduction:

Cellulose is produced in enormous quantities by plants and degraded by fungi and bacteria. Some animals such as cows and termites have symbiotic microbes in their intestines that can digest cellulose. They use this for their food. In this laboratory common cellulose degraders will be used to break down cellulose. The day to day changes and the time needed to decompose a paper strip will be noted.

Pre-lab Questions:

  1. What would be the best source for microbes that degrade paper.
  2. What do you think microbes have that help to break down cellulose?
  3. What would be a control for your experiment? Be specific.
Purpose:

To see what common materials would have microorganisms that would digest cellulose.

Hypothesis:

(State as "If…then…" sentence.)
 

Materials: group of three

Paper towel
Possible cellulose decomposers your group collected
3 erlenmeyer flasks: 125 ml.
3 plastic covers for Flasks
3 tubes of sterile Nutrient Broth
Sterile Water
Masking tape
Mortar and Pestle
Scissors
Spatula
Measuring Devices
Marking Pens
Table sterilant, i.e. LysolTM or Alcohol

Procedure:

    1. Clean your work area.
    2. Gather your materials at your lab station.
    3. Label your three flasks with your name, date, and material in them.
    4. Crush your cellulose decomposer separately with the mortal and pestle.
    5. Place the crushed cellulose digester in separate flasks.
    6. To each of the flasks add 10 ml of nutrient Broth and 50 ml of sterile water.
    7. Insert a strip of paper towel which has been attached to the lid of the flask It should be soaking in the broth water mixture (see diagram above.)
    8. Carefully add equal amounts of your chosen cellulose digesters to flasks two and three. Do not add anything to flask one.
    9. Place your tubes of sterile nutrient broth, sterile water, and cellulose digesters in an area designated by your teacher.
    10. Clean your work area and sketch the experiment in your notebook.
Results: Make observations of the flasks every day in your data book. Do not open the flasks. Be sure to note color, turbidity and smell.

Once the strip begins to be digested, record your results in the chart below. You will have to estimate distances since you should not remove the lid. Devise a consistent system for making estimates.

 Estimating system your group devised:
 
  Data table: copy this in your data book.
FLASK NUMBER AND MICROBE SOURCE
DAYS AFTER DIGESTION BEGINS
NOTES
1              
2              
3              

Analysis and Conclusions:

Graph your results by putting the days on the horizontal axis and the millimeters of paper strip digested on the vertical axis. (Use graph paper for this.)

Compare your results with other class groups.

State your conclusion:
 
 
 
 

Questions for Discussion:

  1. Which sample used was the best "enrichment culture." (Source of organisms that would break down cellulose?) Explain.
  2. What are some other possible sources of organisms that will break down cellulose?
  3. Why would you want to investigate cellulose digesters?
  4. Select another group. Compare your data with theirs and try to account for any differences or similarities.
  5. Where might you find organisms that would digest plastic?
 Back to Cellulose Digesters Page
 
 
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The Woodrow Wilson National Fellowship Foundation 
CN 5281, Princeton NJ 08543-5281 - Tel:(609)452-7007 - Fax:(609)452-0066 
Technical contact: lpt@woodrow.org