Nitrogen-Fixing Bacteria : Behaviors Similar To Organelles
Researchers have discovered nitrogen-fixing symbiotic organisms exhibiting behaviors similar to organelles.
- Nitrogen-fixing bacteria are prokaryotic microorganisms that are capable of transforming nitrogen gas from the atmosphere into “fixed nitrogen” compounds, such as ammonia, that are usable by plants.
- There are two main types of nitrogen-fixing bacteria.
- Symbiotic or mutualistic: These species live in root nodules of certain plants. Plants of the pea family, known as legumes which are some of the most important hosts for nitrogen-fixing bacteria. Examples: Rhizobium, which is associated with plants in the pea family and various Azospirillum species, which are associated with cereal grasses.
- Other nitrogen-fixing bacteria are free-living and do not require a host. They are commonly found in soil or in aquatic environments. Examples: Cyanobacteria Anabaena and Nostoc and genera such as Azotobacter, Beijerinckia and Clostridium.
- Nitrogen is a component of proteins and nucleic acids and is essential to life on Earth.
- Although nitrogen is abundant in the atmosphere, most organisms cannot use it in that form.
- Nitrogen-fixing bacteria accomplish more than 90 percent of all nitrogen fixation and thus play an important role in the nitrogen cycle.
