Question

Write a short note on Nitrogen-fixing bacteria.

Answer 1

Nitrogen fixation: The conversion of atmospheric, industrial, or inorganic nitrogen into such usable forms which can be utilized by living organisms is called Nitrogen fixation.

Nitrogen fixation by bacteria:

1. The fixation of atmospheric nitrogen in plants takes place by free-living or symbiotic bacteria.
2. The free-living bacteria such as Azotobacter bacteria fix the atmospheric nitrogen in the soil, and Azospirillum bacteria form a loose association with the roots of crops such as maize, and sorghum to fix the atmospheric nitrogen into nitrates and nitrites.
3. These bacteria contain an enzyme nitrogenase that combines the atmospheric nitrogen with hydrogen to form ammonia, which is further converted to nitrates and nitrites which can be utilized by plants to make their organic compounds.