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. Microorganisms help break down organic matter, they release essential nutrients and carbon dioxide into the soil, fix nitrogen and help transform nutrients into mineral forms that plants can use through a process of mineralization and nitrogen fixing bacteria improve soil fertility. Soil organic matter and soil organisms are inextricably connected. Microbial biomass is the living component of soil organic matter, and microorganisms are the catalysts for most nutrient-releasing processes. They make it possible for crops to grow and for soils to be productive. Microorganisms play a primary role in regulating biogeochemical systems in virtually all of our planet 's environments. Microbes participate in essential biogeochemical cycling events such as carbon and nitrogen fixation.

Microorganisms play a primary role in regulating biogeochemical systems in virtually all of our planet 's environments. Microbes participate in essential biogeochemical cycling events such as carbon and nitrogen fixation. This is because the microorganisms decompose dead organic waste of plants and animals converting them into simple substances. These substances are again used by other plants and animals. Thus, microorganisms can be used to degrade the harmful and smelly substances and thereby clean up the environment. Microorganisms are responsible for the degradation of organic matter, which controls the release of plant nutrients, but is also important for the maintenance of soil structure and sustainability of soil quality for plant growth. Soil microbes play an important role in nutrient recycling. They decompose organic matter to release nutrients. They are also important to trap and transform nutrients into the soil, which can be taken up by plant roots. Nutrient cycling rate depends on various biotic, physical and chemical factors. Microorganisms help in cleaning up the environment. They decompose dead and decaying matter from plants and animals; convert them into simpler substances which are later used up by other plants and animals. Thus, they are used to breakdown harmful substances. Microorganisms are essential to soil formation and soil ecology because they control the flux of nutrients to plants promote nitrogen fixation, and promote soil detoxification of inorganic and naturally occurring organic pollutants.