Ecological Importance of Bacteria

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  • 0:00 What Are Bacteria?
  • 0:44 Bacteria as Producers
  • 2:37 Bactera as Decomposers
  • 3:31 Symbiotic Bacteria
  • 4:43 Pathogenic Bacteria
  • 5:33 Lesson Summary
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Lesson Transcript
Instructor: Amanda Robb

Amanda holds a Masters in Science from Tufts Medical School in Cellular and Molecular Physiology. She has taught high school Biology and Physics for 8 years.

This lesson is on the ecological importance of bacteria. In this lesson, we'll learn what bacteria are and their place in the ecosystem. We'll go over the different jobs they do and examples of each.

What Are Bacteria?

Although macroscopically, ecosystems on Earth appear to be composed of plants and animals, there are some key players that exist beyond what we can see. Bacteria are tiny, single-celled microbes that help all life exist. They have a very simple structure with no nucleus, a structure that protects the DNA in more complex cells. Bacteria range from helpful organisms that break down dead material and provide food for ecosystems to pathogenic bacteria that can cause disease. Today we'll look at the main roles of bacteria in our environment.

Bacteria as Producers

Producers are organisms that make their own food, which we usually think of as green plants. The truth is, bacteria are the producers in many ecosystems as well. Producers make food for the entire ecosystem, supporting animals that eat plants, or herbivores, which in turn support carnivores. Without producers, there would be no life on Earth. There are bacteria that do photosynthesis using carbon dioxide and sunlight, like plants, and bacteria that do chemosynthesis, where they use chemicals to make food.

Photosynthetic bacteria use light energy from the sun to make food, like plants do. However, bacteria are much simpler than plants. They are only single-celled and have no compartments inside their cells to do specific jobs like plants do. Plants use a compound called chlorophyll to make food from sunlight. Purple photosynthetic bacteria have a related compound called bacteriochlorophyll that allows them to absorb light. Other bacteria like cyanobacteria use a similar compound to chlorophyll called phycocyanin to produce food.

Chemosynthetic bacteria use chemicals from the Earth to make food, not sunlight. These bacteria are famous for providing food for deep-sea vent ecosystems. At the very bottom of the ocean, there is no sunlight, so photosynthetic producers cannot survive. Chemosynthetic bacteria, like mesophilic sulfur bacteria, use sulfur spewed from black smoker vents to produce food for the entire ecosystem.

Bacteria as Decomposers

Decomposers are any organisms that break down dead material and return it to the soil. Think of decomposers as the recyclers of the ecosystem. They take things that would otherwise be trash - dead organisms - and recycle the nutrients in them. Plants can then use these nutrients to grow, and animals eat the plants. The nutrients are returned to the living things. Bacillus subtilis is a common soil bacteria also found in our digestive tract and an example of a decomposer.

Another bacteria, actinobacteria, break down a nutrient-rich compound called humate. Humate is used by farmers as a fertilizer that can be broken down by soil bacteria to other compounds needed for plant growth.

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