Which organisims help convert gaseous nitrogen into ammonia in the nitrogen cycle?

In the nitrogen cycle, nitrogen-fixing bacteria play a crucial role in converting gaseous nitrogen (N₂) into ammonia (NH₃). These bacteria, such as Rhizobium, live in the root nodules of legumes or in the soil, where they convert atmospheric nitrogen into a form that plants can use. Additionally, some free-living bacteria, like Azotobacter, also perform this nitrogen fixation in the soil. This process is essential for replenishing the nitrogen available to plants and, consequently, the entire ecosystem.