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What is Azotobacter?

Last updated date: 18th Mar 2023
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Azotobacter is a genus of free-living or motile diazotrophic bacteria that is oval or spherical and forms thick-walled cysts. They are aerobic and free-living soil microbes that play a pivotal role in nitrogen fixation. The azotobacter is primarily found in alkaline soils and aquatic environments and also on some plants. The azotobacter biofertilizer uses are renowned all over the world. It is noteworthy to highlight that azotobacter is typically used as a model organism for studying and analyzing diazotrophs. In addition to being excellent biofertilizers, azotobacter is also used to produce food additives and some biopolymers.

The azotobacter was first discovered by a Dutch microbiologist, Martinus Beijerinck in 1901. Martinus was one of the founding pioneers of environmental microbiology and described azotobacter chroococcum as the first aerobic, free-living nitrogen fixer. After that, the azotobacter vinelandii was discovered in 1909, followed by the discovery of several other variants of the azotobacter. Now that we have covered the fundamentals of the azotobacter, let us get into a detailed study of the azotobacter chroococcum and azotobacter vinelandii.

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Azotobacter Chroococcum

It is a nitrogen-fixing bacteria that plays an integral part as a biofertilizer, fungicide, and nutrient indicator. The azotobacter chroococcum is usually found in soils of moderate temperature with a neutral pH level. The soil must be rich in phosphorus to cater to the nitrogen fixation process by the azotobacter. The chroococcum is widely used in the realm of crop production. One study reveals a correlation between increased crop production and the presence of azotobacter chroococcum. The bacterium has also been proven to galvanize the growth of crops in polluted soils.

Azotobacter Vinelandii

The azotobacter vinelandii can be easily cultured and grown. It is a Gram-negative diazotrophic bacterium that can fix nitrogen when it is grown aerobically. It is a free-living bacterium that produces fluorescent pigments. Now that we have learned about the two primordial variants of azotobacter, let us discuss the process of nitrogen fixation.

Azotobacter Nitrogen Fixation

We can understand biological nitrogen-fixing as the mechanism wherein a microorganism mediates fixing elemental nitrogen via enzymes known as nitrogenase. As such, nitrogen fixation entails the conversion of atmospheric nitrogen (N2) into ammonium that the plant's roots can readily absorb. The azotobacter is a free-living, nitrogen-fixing bacterium, they fix molecular nitrogen directly from the atmosphere without any symbiotic relations with plants. The azotobacter is equipped with various enzymes that foster nitrogen fixation. As the mechanism of nitrogen fixation is intensely sensitive to the presence of oxygen, the azotobacter developed a particular defense mechanism against oxygen which intensifies their metabolism and reduces the concentration of oxygen from the cells.

Characteristics of the Azotobacter

Let us now glance at the various characteristics of the Azotobacter.

  • The azotobacter fertilizer is proven to be highly efficient for plant health.

  • They are rod-shaped and Gram-negative in the Gram staining process.

  • The azotobacter moves by means of their flagellum, which is located at their end.

  • Some species of azotobacter produce a pigment that adds a yellow-green, red-violet, or brownish-black hue to the soil they are located in.

  • The size of the azotobacter is quite large as compared to other bacteria. The former is almost as big as a yeast cell.

  • The azotobacter can survive in harsh conditions via two mechanisms – the cyst and the slime.

Azotobacter Biofertilizer Uses

It is crucial to remember that azotobacter biofertilizer uses have shown that they are of tremendous help in ensuring plant health. The azotobacter is widely used in agriculture to increase soil fertility and stimulate plant growth. The presence of azotobacter is prominent in biofertilizers. They are also crucial in the manufacture of alginic acid that is renowned in medicine as an antacid. It is also essential to highlight that azotobacter is critical to the food industry as well.

In conclusion, we can safely assert that azotobacter is a crucial part of our environment and they are indispensable for nitrogen fixation and plant health. Microorganisms including azotobacter and rhizobium play a vital role in the development of flora and fauna on earth. We must recognize their roles and identify their importance. You can take a look at an azotobacter ppt to grasp more information on the subject. You can also learn the azotobacter biofertilizer production process in detail to know more about it.

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FAQs on Azotobacter

1. What is mass multiplication of azotobacter?

Ans: Mass multiplication of azotobacter is a process where they are artificially inoculated. The process entailed transferring the azotobacter inoculants to a sterile flask and incubating them on a rotary shaker for a few days at 30 degrees centigrade. The broth acts as the initial culture that can be utilized for the mass multiplication or production of the azotobacter inoculants. It is when the density of the inoculums becomes 10; the inoculants should be prepared. The broth is then mixed with a carrier, and the curing is done for a week in such a way that 40 percent of the moisture is maintained. Suitable carrier materials are materials followed by sterilization by autoclaving. After that, the carrier-based inoculants are packed in polythene bags and sent to the market.

2. What is azotobacter colony morphology?

Ans: Azotobacter is relatively large in size. The bacteria are generally oval in shape and may take various forms, such as rods and spheres. The colony morphology of azotobacter can be described as a glistening opaque white-colored mass with a flat and irregular shape. The growth is typically smooth and soft. The diameter of the colony is around 15mm. When we magnify by 10000 times, we can see that the cells of the azotobacter colony are bacilli and possess a negative Gram staining.

3. Where are azotobacter typically found?

Ans: All variants of azotobacter are easily found in neutral and weakly alkaline soils. They are also seen in the Arctic and Antarctic regions of the earth. Low pH levels are crucial for the growth of azotobacter. We can also observe them in aquatic and marshy habitats.

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