What type of bacteria is responsible for nitrogen fixation?

Nitrogen-fixing bacteria are unique in their ability to convert atmospheric nitrogen (N2) into a form that can be utilized by plants, specifically ammonia (NH3) or related compounds. This process is vital for agriculture and the overall health of ecosystems, as atmospheric nitrogen is abundant but not directly usable by most organisms. Nitrogen-fixing bacteria, such as those in the genera Rhizobium and Azotobacter, often form symbiotic relationships with the roots of certain plants, particularly legumes, creating nodules where this conversion takes place.

This ability to convert nitrogen makes nitrogen-fixing bacteria crucial for improving soil fertility and promoting plant growth. Unlike denitrifying bacteria, which convert nitrates back into atmospheric nitrogen, or decomposing bacteria, which break down organic matter to release nutrients, nitrogen-fixing bacteria play a direct role in capturing and integrating atmospheric nitrogen into biological systems. Pathogenic bacteria are related to disease and do not contribute to nitrogen fixation at all. Therefore, nitrogen-fixing bacteria are fundamental players in the nitrogen cycle and are essential for sustaining plant life and agricultural productivity.