Difference between Azotobacter and Azospirillum

What is the Difference between Rhizobium and Azotobacter?

Rhizobium species form an endosymbiotic relationship with leguminous plants during nitrogen fixation. On the other hand, Azotobacter species are free-living bacteria that fix nitrogen in soil.

How do you Identify Azotobacter?

Azotobacter spp. exhibit gram-negative character. They form slimy, smooth, dark colonies. Biochemical tests, as well as 16S rRNA sequencing methods can be used to identify them.

Is Azospirillum Symbiotic or Non Symbiotic?

Azospirillum species are primarily found in an associative relationship with many crop plants such as rice, wheat, sorghum, maize.

Is Azospirillum a Cyanobacteria?

No, Azospirillum spp. are non-photosynthetic rhizobacteria that promote plant growth by producing plant hormones and other metabolites.

Is Azospirillum Gram Positive or Gram Negative?

All members of the genus Azospirillum are Gram-negative and appear pink or red under the microscope after Gram staining.

Is Azospirillum a Nitrogen Fixer?

Yes, Azospirillum is a nitrogen-fixing bacterium that forms a symbiotic relationship with plants to fix atmospheric nitrogen for their growth.

What are the Advantages of Using Azospirillum over Azotobacter?

Azospirillum offer better root surface colonization, wider plant compatibility, and additional growth-promoting benefits as compared to Azotobacter.

What are the Similarities Between Azotobacter and Azospirillum?

Azotobacter and Azospirillum are both nitrogen-fixing bacteria that form symbiotic relationships with plants, helping in their growth. They share similarities in increasing soil fertility and reducing the need for synthetic fertilizers.

The main difference between Azotobacter and Azospirillum lies in the way these nitrogen fixers are found in nature. The Azotobacter species are non-symbiotic nitrogen-fixing bacteria, whereas the Azospirillum species are associative rhizobacteria that fix nitrogen. Azotobacter are aerobic, free-living species. They are widely distributed in soils and waters. On the contrary, Azospirillum spp. are microaerophilic and often found in a beneficial association with plants.

They are present either in the rhizospheres or the roots of important crop plants. Both of them are diazotrophs, meaning they are capable of biological nitrogen fixation (BNF). In this article, we will look into the differences between Azotobacter and Azospirillum in detail.