Cyanobacteria and other microorganisms for example in the Rhizobium family https://en.wikipedia.org/wiki/Rhizobium Can bind free nitrogen and form NH3 available to plants. Other microorganisms can change NH3 to NO2- and NO3-, and back to free N2. This is the nitrogen cycle. Access to fixed nitrogen is necessary for all living things. Plants take it up in inorganic form. Therefore, the supply of nitrogen means better growing conditions.

Dr Arne Andersen thank you for your contribution to the discussion

Microorganisms play an important role in improving soil fertility and involved in all aspects of N cycling, including N2 fixation, nitrification, denitrification and ammonification. They decompose plant residues, soil organic matter and release inorganic nutrients that can then be taken up by plants.The role of nitrogen-fixing bacteria is to supply plants with the vital nutrient that they cannot obtain from the air themselves. Nitrogen-fixing microorganisms do what crops can’t get assimilative N for them. Bacteria take it from the air as a gas and release it to the soil, primarily as ammonia. Bacteria play a central role: Nitrogen-fixing bacteria, which convert atmospheric nitrogen to nitrates. Bacteria of decay, which convert decaying nitrogen waste to ammonia. Nitrifying bacteria, which convert ammonia to nitrates/nitrites. Microorganisms play a dominant role in the biogeochemical cycling of nutrients. They are rightly praised for their facility for fixing both carbon and nitrogen into organic matter, and microbial driven processes have tangibly altered the chemical composition of the biosphere and its surrounding atmosphere. Microorganisms play a dominant role in the biogeochemical cycling of nutrients. They are rightly praised for their facility for fixing both carbon and nitrogen into organic matter, and microbial driven processes have tangibly altered the chemical composition of the biosphere and its surrounding atmosphere. They are vital as they recycle elements and store them too, and regulate the vital elements through the physical facets. These cycles depict the association between living and non-living things in the ecosystems and enable the continuous survival of ecosystems. Microorganisms and fungi break down wood and return carbon to the biogeochemical cycles. If these organisms become absent, carbon would accumulate in the wood, where it could not be recycled into the environment. The fixation of nitrogen is dependent on microorganisms mostly through biological nitrogen fixation. Bacteria affect local and global biogeochemical cycles by absorbing organic carbon and nutrients and therefore, the study of these microorganisms is key to understanding ecosystem dynamics. Soil microbes can break down plant organic matter to carbon dioxide or convert it to dissolved organic carbon (DOC) compounds. This leads either to long-term carbon storage, because DOC can bind to soil particles, or to the release of carbon back to the atmosphere as carbon dioxide. In fact, they help you digest food, protect against infection and even maintain your reproductive health. We tend to focus on destroying bad microbes. But taking care of good ones may be even more important. Organisms that are involved in nitrogen cycles are nitrogen fixers, nitrifying bacteria, and denitrifying bacteria. Example: Nitrosomonas, Rhizobium, Pseudomonas, and Thiobacillus, etc. 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.

Dr Rana Hamza Shakil thank you for your contribution to the discussion

Bacteria play many roles in our ecosystem. Bacteria are decomposers which break down dead material and recycle it. They also can be producers, making food from sunlight, such as photosynthetic bacteria, or chemicals, such as chemosynthetic bacteria. Bacteria are present in almost all ecosystems, both terrestrial and aquatic, and play crucial ecological roles. As bacteria mediate the mineralization of labile carbon. Moreover, anammox bacteria play a vital role in the nitrogen cycle and rhizobia are involved in nitrogen fixation. Microorganisms play a dominant role in the biogeochemical cycling of nutrients. They are rightly praised for their facility for fixing both carbon and nitrogen into organic matter, and microbial driven processes have tangibly altered the chemical composition of the biosphere and its surrounding atmosphere. Microorganisms play an important role in improving soil fertility and involved in all aspects of N cycling, including N2 fixation, nitrification, denitrification and ammonification. They decompose plant residues, soil organic matter and release inorganic nutrients that can then be taken up by plants. The bacteria in our bodies help degrade the food we eat, help make nutrients available to us and neutralize toxins. Also, they play an essential role in the defense against infections by protecting colonized surfaces from invading pathogens. Bacteria in the digestive system break down nutrients, such as complex sugars, into forms the body can use. Non-hazardous bacteria also help prevent diseases by occupying places that the pathogenic, or disease-causing, bacteria want to attach to. Some bacteria protect us from disease by attacking the pathogens. Nitrogen-fixing bacteria in the soil and within the root nodules of some plants convert nitrogen gas in the atmosphere to ammonia. Nitrifying bacteria convert ammonia to nitrites or nitrates. Ammonia, nitrites, and nitrates are all fixed nitrogen and can be absorbed by plants. Bacteria are important in the carbon cycle, because they produce carbon dioxide by breaking down dead animal and plant matter. Therefore, they act as decomposers. Bacteria are important in the nitrogen cycle, because nitrogen fixing bacteria found in the root nodules of legumes convert nitrogen to nitrates. Plants take up nitrogen compounds through their roots. Animals obtain these compounds when they eat the plants. When plants and animals die or when animals excrete wastes, the nitrogen compounds in the organic matter re-enter the soil where they are broken down by microorganisms, as decomposers.