Biological nitrogen fixation is the process by which nitrogen-fixing bacteria transform atmospheric nitrogen (N2) into forms that can be used. The roots of some plants, referred to as legumes (e.g., soybeans, peas, and clover), develop into specialized organs called nodules, where this amazing process occurs. These leguminous plants form a symbiotic relationship with the nitrogen-fixing bacteria, which in turn gives them a necessary nutrient in exchange for obtaining carbohydrates and other organic compounds as sustenance. This is how the procedure goes:
Leguminous plants that are grown in nitrogen-deficient soils release special chemical signals known as flavonoids that lead to the production of nodules. The Rhizobium, Bradyrhizobium, and Azorhizobium species of nitrogen-fixing bacteria that are prevalent in the soil are drawn to these flavonoids.
Infection and colonization: The nitrogen-fixing bacteria travel toward the roots of the plant in response to the flavonoids, starting the process of infection. Infectious threads are created by the bacteria when they pass through the root hairs and enter the root cortex, where they continue to proliferate and disseminate throughout the root cells.
Nodule formation: The plant develops a nodule on its roots as the infected threads keep expanding. The bacteria and plant cells coexist inside the nodule to form a special environment known as the symbiosome. The root cells’ symbiosome, a membrane-bound compartment, is where the nitrogen fixation process happens.
Nitrogen fixation: The nitrogen-fixing bacteria in the symbiosome create an enzyme called nitrogenase that turns atmospheric nitrogen (N2) into ammonia (NH3).
