What organisms are involved in nitrogen faxation?

Nitrogen fixation primarily involves certain bacteria and archaea that can convert atmospheric nitrogen (N₂) into ammonia (NH₃), a form usable by plants. Key organisms include free-living bacteria like Azotobacter and cyanobacteria, as well as symbiotic bacteria such as Rhizobium, which form nodules on the roots of leguminous plants. Some archaea, particularly in extreme environments, also contribute to this process. Overall, these organisms play a crucial role in the nitrogen cycle, enhancing soil fertility and supporting plant growth.