What is Azospirillum?
The genus Azospirillum was also initially described by M.W. Beijerinck. It belongs to the class of alpha-Proteobacteria and the family Azospirillaceae.
- The genus mainly includes nitrogen-fixing rhizobacteria. They can be found in soil and freshwater but are most abundant in the rhizospheres and roots of crop plants like corn, rice, wheat, sugarcane etc.
- These bacteria enhance plant growth by forming beneficial associations with them. Hence they are called plant growth-promoting rhizobacteria (PGPR).
- Azospirillum lipoferum, Azospirillum brasilense and Azospirillum amazonense efficiently fix nitrogen in the rice rhizosphere. They also stimulate plant growth by producing and releasing various plant hormones.
- Azospirillum species are gram-negative and microaerophilic. Some are facultative anaerobes, capable of surviving without oxygen.
- They can tolerate a wide range of soil pH, from 5 (acidic) to 9 (alkaline). They are curved rods and motile. The cells usually remain dispersed.
- They can produce spherical cysts in response to nutrient deprivation or desiccation. Their colonies have a circular, flat morphology with prominent red colouring and wavy edges.
Difference between Azotobacter and Azospirillum
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.
Table of Content
- Difference Between Azotobacter and Azospirillum
- What is Azotobacter?
- What is Azospirillum?
- Similarities Between Azotobacter and Azospirillum
- Usage of Azotobacter and Azospirillum
- Conclusion – Difference between Azotobacter and Azospirillum
- FAQs on Difference between Azotobacter and Azospirillum
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