What organism converts nitrogen?

Nitrogen-fixing bacteria, such as those in the genus Rhizobium, convert atmospheric nitrogen (N₂) into ammonia (NH₃) through a process known as nitrogen fixation. These bacteria often form symbiotic relationships with the roots of leguminous plants, where they provide the plants with usable nitrogen in exchange for carbohydrates. Other organisms, such as certain cyanobacteria, also contribute to nitrogen fixation in various ecosystems.