Nitrogen Fixing Bacteria
Nitrogen-fixing bacteria are naturally occuring microorganisms that convert atmospheric nitrogen (N₂) into bioavailable forms such as ammonia (NH₃) or ammonium (NH₄⁺). This natural process, known as biological nitrogen fixation, is crucial in nature as well as for maintaining soil fertility and ensuring plant growth without relying heavily on synthetic fertilizers. These bacteria play an integral role in the nitrogen cycle, supporting sustainable agriculture and environmental conservation.
What is Nitrogen Fixing Bacteria?
Nitrogen-fixing bacteria are specialized microbes capable of converting inert nitrogen gas into plant-usable forms through enzymatic action, primarily facilitated by nitrogenase.
They can be classified into two main categories:
1. Symbiotic Nitrogen Fixing Bacteria
These bacteria form mutualistic relationships with plants, particularly legumes.
Rhizobium bacteria are the most well-known symbiotic nitrogen fixers. They colonize the roots of legumes (e.g., beans, peas, lentils) and form nodules where nitrogen fixation occurs.
In return, the plant supplies carbon compounds as energy for the bacteria. This relationship is often referred to as legume-rhizobia symbiosis.
2. Free-Living Nitrogen Fixing Bacteria
Unlike symbiotic types, these bacteria fix nitrogen independently in the soil without the need for plant hosts.
Examples include Azotobacter species and certain Cyanobacteria.
They thrive in organic-rich soils and play an essential role in soil nitrogen enhancement.
