The Role of Microorganisms in the Ecosystem


This lab activity uses a controlled experiment to demonstrate different rates of decomposition for a variety of man-made and natural materials.  Microorganisms are ubiquitous in the environment, where they have a variety of essential functions. Many microbes are uniquely adapted to specific environmental niches, such as those that inhabit the Dead Sea (Halobacterium), the bacteria and cyanobacteria that inhabit the boiling water springs in Yellowstone National Park, and Chlamydomonas nivalis, the algae that causes "pink snow." Microbes also play an essential role in the natural recycling of living materials. All naturally produced substances are biodegradable, which means that they can be broken down by living organisms, such as bacteria or fungi. Composting is an example of biodegradation that is easy to investigate the classroom. An examination of conditions that foster or impede composting gives insight to growth conditions of microorganisms as well as the proper function of the ecosystem.   

Intended Audience



5-8 X
9-12 X
Learning Objectives


By completing this activity, the student will be able to:

  1. Understand the steps used in a controlled experiment.
  2. Describe the variables in this experiment. 
  3. Analyze the data by determining the rate of decomposition for each material. 
  4. Compare and contrast the nutritional requirements for microbes and humans.   

Necessary Student Background

Students should have prior knowledge of the concepts of landfills, compost piles, and an overview of bioremediation.  This lesson will further investigate the concept of bioremediation, and how microbes can be beneficial in the maintenance of our environment


the use of microorganisms to remove or detoxify undesired or toxic chemicals from the environment.
Bioaugmentation: the addition of necessary nutrients required to speed up the rate of degradation of a contaminant.Xenobiotic compounds: compounds that are chemically synthesized and do not  exist naturally. Microbial plastic: a product produced by microbes that is an
alternative to plastic, having similar qualities but is biodegradable.

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The Role of Microorganisms in the Ecosystem (13 pages)