* Decompose organic matter, releasing nutrients back into the environment that can be used by plants and animals.
* Help to cycle nutrients through the environment, such as the nitrogen cycle and the carbon cycle.
* Contribute to the breakdown of pollutants and toxins in the environment.
* Help to provide food for other organisms, such as insects and fish.
* Play a role in the production of oxygen and the removal of carbon dioxide from the atmosphere.
Fungi
* Decompose organic matter, releasing nutrients back into the environment that can be used by plants and animals.
* Form symbiotic relationships with plants, such as mycorrhizae, which help them to absorb water and nutrients from the soil.
* Produce antibiotics and other compounds that can inhibit the growth of bacteria and other organisms.
* Help to recycle nutrients through the environment, such as the carbon cycle and the nitrogen cycle.
Protists
* Are a food source for other organisms, such as zooplankton and fish.
* Help to control the population of other organisms, such as bacteria and algae.
* Play a role in the production of oxygen and the removal of carbon dioxide from the atmosphere.
* Contribute to the decomposition of organic matter and the cycling of nutrients.
Bacteria
* Decompose organic matter, releasing nutrients back into the environment that can be used by plants and animals.
* Help to cycle nutrients through the environment, such as the nitrogen cycle and the carbon cycle.
* Contribute to the breakdown of pollutants and toxins in the environment.
* Help to provide food for other organisms, such as insects and fish.
* Play a role in the production of oxygen and the removal of carbon dioxide from the atmosphere.