Ecological Role of Microorganisms

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  • 0:01 Definition of Microorganisms
  • 0:55 Role in Organisms
  • 1:56 Role in Ecosystems
  • 3:51 Lesson Summary
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Lesson Transcript
Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

What are microorganisms? And why are they an important part of ecosystems? Learn about the role of microorganisms both inside large organisms like humans, and in the ecosystem as a whole.

Definition of Microorganisms

If you're a germophobe, this lesson probably isn't for you. That's because I'm about to tell you something you'll find horrifying: microorganisms are absolutely everywhere. They're on every surface, every wall, all over your skin, and inside your body. While that might make you shudder and give you the creeps, most of them are completely harmless, and some of them are hugely important to organisms and the ecosystem as a whole.

Bacteria are everywhere, and most of them are perfectly safe
Bacteria are everywhere, and most of them are perfectly safe

Microorganisms are organisms (lifeforms) that are small enough to be microscopic. In other words, they require a microscope to be seen. Examples of types of microorganisms include bacteria, protozoa, viruses, and fungi. In this lesson, we're going to take a look at how they impact large organisms and ecosystems, both for their good and bad.

Role in Organisms

Inside organisms like humans, microorganisms can be wonderfully useful, or terribly destructive. Most people know that bacteria and viruses can make you sick, and that some can even be deadly; but did you know that most microorganisms inside you have no negative effects, or are even useful?

Some kinds of bacteria can cause infections
Some kinds of bacteria can cause infections

For example, we all have bacteria and viruses in our intestines which help to digest food and make the environment inhospitable for more dangerous microorganisms. In fact, after being treated with antibiotics, you might find you get sick not long after because the antibiotics may have killed useful bacteria in your intestines. By killing off safe bacteria, the dangerous invaders have no competition and can then spread more easily. Having so many microorganisms inside your body also serves as a training ground for your immune system, making it stronger. There is even some evidence that microorganisms absorb toxins and help reduce feelings of stress.

Role in Ecosystems

Animals are only one small part of an ecosystem. For an ecosystem to work, it has to have many organisms that all work together in a continuous cycle. Microorganisms form part of that cycle, and because of their huge numbers, the part they play is an important one. Microorganisms have several vital roles in ecosystems: decomposition, oxygen production, evolution, and symbiotic relationships.

Decomposition is where dead animal or plant matter is broken down into more basic molecules. This process only happens because of the microorganisms that find their way into the dead matter. The process of decomposition provides nutrients that future plants and animals will be able to reuse, making soil more fertile. Plants would not continue to grow without it - not to mention the world be really cluttered with dead animals and plants without it.

Decomposition provide nutrients for new life
Decomposition provide nutrients for new life

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