What role do nitrogen-fixing bacteria play in root nodules?

Nitrogen-fixing bacteria in root nodules play a critical role in the nitrogen cycle by converting atmospheric nitrogen (N2) into ammonia (NH3), which is a form of nitrogen that plants can utilize for growth. These bacteria possess the enzyme nitrogenase, which enables them to break the strong triple bond of atmospheric nitrogen and incorporate it into organic molecules. This process not only enhances soil fertility but also helps establish a symbiotic relationship with leguminous plants, allowing them to thrive in nitrogen-poor soils.

The conversion of atmospheric nitrogen into ammonia is essential because nitrogen is a vital nutrient required for the synthesis of amino acids, proteins, and nucleic acids in plants. By facilitating this conversion, nitrogen-fixing bacteria enable legumes and other associated plants to access nitrogen in a form that can be easily absorbed through their roots, which ultimately supports plant growth and productivity.