The primary function of nitrogen-fixing bacteria is to provide the necessary nutrients that the host plants cannot acquire from the atmosphere directly. Furthermore, nitrogen-fixing bacteria benefit in promoting plant growth, which contributes to the enhancement of agricultural yield in the short run.
Rhizobium is a species of nitrogen-fixing Gram-negative rhizobacteria in the soil. It has an endosymbiotic nitrogen-fixing link with a leguminous plant roots system.
Azospirillum is a Gram-negative bacteria that also has the ability to fix nitrogen. This bacteria encourages the growth and development of plants.
3. Azospirillum brasilense
Azospirillum brasilense is a gram-negative bacteria that binds nitrogen from the atmosphere into the soil and promotes plant growth.
Frankia is a gram-positive bacteria that belong to the nitrogen-fixing bacteria genus Frankia. This bacteria can be found in the root system of plants.
Bradyrhizobium is a gram-negative bacteria found in the soil. Bradyrhizobium bacteria are essential for creating symbiotic nodules in legumes, which allows them to fix nitrogen.
6. Azotobacter vinelandii
Azotobacter vinelandii is a diazotrophic gram-negative bacterium. While growing aerobically mature, it can fix nitrogen. Many vitamins and phytohormones are produced in soils by this bacteria.
7. Bradyrhizobium japanicum
Bradyrhizobium japanicum is a nitrogen-fixing microsymbiotic bacteria. It is a gram-negative bacteria which is found in the soil as a variety of leguminous plants’ root nodule bacteria.
8. Ensifer meliloti
Ensifer meliloti is a bacteria that is Gram-negative. In the soil, it has the nitrogen-fixing ability.
9. Ensifer adhaerens
In symbiosis with leguminous plants, ensifer adhaerens is a soil bacteria that can fix nitrogen.
A gram-negative Alphaproteobacterium called Hypomicrobiales. It’s a nitrogen-fixing rhizobacterium. It also has a symbiotic association with plant roots.
Derxia is a Gram-negative bacteria that contributes to the nitrogen fixation process.
Beijerinckia is a member of the Beijerinckiaceae family. It is a nitrogen-fixing aerobic bacteria that also has the ability to reduce nitrogen.
13. Clostridium kluyveri
Clostridium kluyveri is a member of the Clostridiaceae family. It is a nitrogen-fixing Gram-positive bacteria that dwell in soil.
14. Klebsiella oxytoca
Klebsiella oxytoca is a Klebsiella bacteria that belongs to the genus Klebsiella. It’s a Gram-negative bacteria that eliminates large amounts of nitrogen from the atmosphere.
15. Azotobacter chroococcum
Azotobacter chroococcum is an aerobic nitrogen-fixing bacteria. It is found in the soil and contributes to the conversion of atmospheric nitrogen to soil-usable nitrogen.
16. Azotobacter salinestris
The bacteria Azotobacter salinestris is gram negative. It helps in nitrogen fixation. It can be found in soil as well as in water.
17. Azotobacter armeniacus
Azotobacter armeniacus is a bacteria that promotes plant growth and nitrogen fixation.
18. Azorhizophilus paspali
Azorhizophilus paspali is a type of bacteria that serves in nitrogen fixation. This bacteria has the ecology of the aerobic mode.
19. Azotobacter macrocytogenes
Azotobacter macrocytogenes is a bacterium from the genus Azotobacter that serves in nitrogen fixation in soil.
20. Hay bacillus
Bacillus subtilis, often known as Hay Bacillus, is a Gram-positive bacteria. It has the potential to fix nitrogen. It can be found in the soil as well as human and animal gastrointestinal tracts.
21. Bacillus cereus
Bacillus cereus is a Gram-positive bacterium. It is present in the soil, marine sponges, and food and has the potential to fix nitrogen. It also helps plants grow.
22. Anthrax bacterium
The anthrax bacterium is a microorganism that can fix nitrogen in the atmosphere and is found in the root nodules of leguminous plants.
23. Bacillus megaterium
Bacillus megaterium is a Gram-positive bacteria with a stable and vigorous plant growth pattern. It also contributes to nitrogen fixation from the atmosphere.
24. Bacillus pumilus
Bacillus pumilus belongs to the Bacillaceae family of Gram-positive bacteria. It can be found in the soil. It’s a microorganism that fixes nitrogen.
25. Bacillus thuringiensis
Bacillus thuringiensis is a soil-borne bacteria belonging to the Bacillaceae family. It often fixes nitrogen.
26. Bacillus licheniformis
Bacillus licheniformis belongs to the Bacillaceae family of bacteria. It can be found in the soil and helps to fix nitrogen.
27. Bacillus mycoides
Bacillus licheniformis is a gram-positive bacteria from the Bacillaceae family. It can be found in the soil and helps to fix nitrogen.
28. Lysinibacillus fusiformis
Lysinibacillus fusiformis is a gram-positive bacteria from the Bacillaceae family. It has been reported to fix nitrogen from the atmosphere while also promoting plant developmental growth.
29. Paenibacillus macerans
Paenibacillus macerans is a diazotrophic bacteria in the Bacillales order. It can fix nitrogen and contribute to the fermentation process.
30. Alkalihalobacillus clausii
The bacteria Alkalihalobacillus clausii belongs to the Bacillales order. It can be found in both the soil and the gastrointestinal system of mammals. In the nitrogen fixation process, it can convert atmospheric nitrogen to ammonia.
31. Clostridium sporogenes
Clostridium sporogenes is a Gram-positive bacteria from the Clostridiaceae family. Clostridium sporogenes, unlike its clostridium genus, have been discovered to fix nitrogen from the atmosphere.
32. Clostridium histolyticum
Clostridium histolyticum belongs to the Clostridiaceae family of gram-positive bacteria. It can be found in the soil, as well as in the waste of animals and humans. It assists in the fixing of nitrogen from the atmosphere.
33. Clostridium acetobutylium
Clostridium acetobutylium, often known as the Weizmann Organism, is a bacteria that belongs to the Eubacteriales order. It is a nitrogen-fixing bacteria that transforms atmospheric nitrogen into ammonia.
34. Klebsiella pneumonia
Klebsiella pneumoniae is a Gram-negative bacteria from the Klebsiella genus. It’s a free-living microbe that fixes nitrogen from the atmosphere into the soil for later use.
35. Klebsiella granulomatis
Klebsiella granulomatis belongs to the genus Klebsiella and is a Gram-negative bacteria. It is important in the ecosystem since it is a nitrogen-fixing bacteria.
36. Klebsiella terrigena
Klebsiella terrigena is a genus of Gram-negative bacteria in the Klebsiella genus. It can be found in both soil and water. It’s an anaerobic bacterial species that can fix nitrogen.
37. Bacillus rhizosphaerae
Bacillus rhizosphaerae is a Gram-positive diazotrophic bacteria. It is found in the soil and functions as a microbial bio-fertilizer as well as a potential nitrogen fixer.
38. Azotobacter tropicalis
The bacteria Azotobacter tropicalis belongs to the genus Azotobacter. It’s a nitrogen-fixing bacteria that transforms nitrogen from the atmosphere into usable nitrogen in the soil for plants to use in biological activities.
39. Bacillus amyloliquefaciens
Bacillus amyloliquefaciens belongs to the Bacillales order of bacteria. It colonizes plant roots and fixes nitrogen from the atmosphere for them.
40. Bacillus nitratireducens
Bacillus nitratireducens is a Gram-positive bacteria that helps plants develop by fixing nitrogen.
41. Bacillus pacificus
Bacillus Pacificus is a gram-positive bacteria that is a facultative anaerobe. These bacteria perform the same function as the other bacillus group in fixing atmospheric nitrogen into the soil for plant growth.
Symbiotic nitrogen-fixing bacteria examples:
There are many nitrogen-fixing bacteria in the soil. Still, some of them cannot fix nitrogen on their own, necessitating a beneficial collaboration with a host plant to carry out their activities.
Therefore, by maintaining a symbiotic relationship with the host plant legumes, the bacterium provides shelter in the legumes. And in exchange, it fixes atmospheric nitrogen into the soil, supplying the plant with usable nitrogen for growth and nourishment. These microscopic bacteria are known as symbiotic nitrogen-fixing bacteria.
Rhizobium falls into the Rhizobiaceae family of gram-negative bacteria that dwell in soil. Because it thrives in a symbiotic association with plant legumes, it operates as a symbiotic nitrogen-fixing bacteria.
It colonizes the rhizomes of the host plant, causing the roots to develop nodules to contain the bacteria, and then it proceeds to fix the nitrogen that the plant requires.
Azospirillum is a Gram-negative bacteria from the Rhodospirillales order. It is a rhizosphere bacteria that fix atmospheric nitrogen into the soil through a symbiotic relationship with host plant legumes. Leguminous plants benefit from it as it promotes growth in them.
Frankia belongs to the Frankiaceae family of plants. It’s a nitrogen-fixing bacteria that works in partnership with actinorhizal plants in a symbiotic relationship. It also causes the production of root nodules in plants.
Mesorhizobium are soil-dwelling Gram-negative symbiotic bacteria. Creating a symbiotic association with Lotus plants’ root nodules fixes nitrogen in the atmosphere.
Sinorhizobium is a Gram-negative bacterium found in the rhizosphere. Ensifer is another name for it. It has the ability to perform the production of root nodules in Trigonella legumes. In exchange, it fixes nitrogen from the atmosphere into the soil, allowing it to grow.
Aerobic nitrogen-fixing bacteria examples:
In the nitrogen cycle, aerobic nitrogen-fixing bacteria are the sort of bacteria that live freely in the environment. To accomplish their function, these bacteria must be exposed to aerobic conditions. Furthermore, it releases it in an oxygen-rich environment to accomplish these reactions with oxygen-sensitive enzymes.
1. Azotobacter salinestris
Azotobacter salinestris is a Gram-negative bacteria that is aerobic. It fixes nitrogen from the atmosphere aerobically.
2. Beijerinckia indica
Beijerinckia indica is a nitrogen-fixing aerobic bacterium. It’s a free-living organism that can convert atmospheric nitrogen into ammonia, which plants can use.
3. Azotobacter vinelandii
Azotobacter vinelandii is a nitrogen-fixing bacteria that fixes nitrogen in the soil and releases it as ammonium ions for the plants.
4. Beijerinckia mobilis
Beijerinckia mobilis is a bacteria that absorbs nitrogen from the atmosphere in an aerobic manner. It has a lot of nitrogenase enzymes, which could reduce nitrogen.
Anaerobic nitrogen-fixing bacteria examples:
Anaerobic nitrogen-fixing bacteria are bacteria that undergo nitrogen fixation without using oxygen. Saprophytic bacteria are those that execute organic activities.
1. Clostridium cadaveris
Clostridium cadaveris is a gram-positive anaerobic bacterium. Clostridium is a bacterial genus and it is capable of surviving without oxygen.
2. Clostridium novyi
Clostridium novyi is a Gram-positive bacteria belonging to the Clostridium genus. It is a pathogenic anaerobic bacterium because it can exist without oxygen or air.
3. Clostridium sordellii
Clostridium sordellii is a kind of gram-positive bacteria found in soil. It is most typically anaerobic bacteria that fix nitrogen and live without the use of oxygen.
4. Clostridium estertheticum
Clostridium estertheticum is a clostridial genus. This bacteria is gram-positive. It is an anaerobic bacteria that grows without the use of oxygen.
Rhodospirillum is a Gram-negative bacteria that can grow in various environments, including aerobic and anaerobic conditions.
Associative nitrogen-fixing bacteria examples:
Associative nitrogen-fixing bacteria are bacteria that participate in the process of associative nitrogen fixation, which involves bacteria close to plants converting nitrogen gas to ammonia.
1. Azotobacter paspali
Azotobacter paspali is a soil bacteria found in the rhizosphere. It forms a symbiotic association with grasses without forming nodules.
2. Azospirillum brasilense
Azospirillum brasilense is a Gram-negative bacteria that lives in free-living soil. It belongs to the Rhodospirillales family. Leguminous plants fix nitrogen through the production of nodules.
Beijerinckia is a nitrogen-fixing bacteria that is not symbiotic. It’s also a nitrogen-fixing bacteria that work in groups.
Rhodobacter is a light-loving bacteria that thrive in anaerobic circumstances. It is also an Associative nitrogen-fixing bacterium.
Cyanobacteria are Gram-negative bacteria that assist in the nitrogen fixation process. It also participates in biological processes in the environment as an associative nitrogen-fixing bacteria.
Non-leguminous nitrogen-fixing bacteria examples:
The bacteria that fix nitrogen in non-leguminous plants are known as non-leguminous nitrogen-fixing bacteria. These bacteria can survive without a host plant’s root nodules.
Frankia is a nitrogen-fixing actinobacterium from the Frankiaceae family. It is a free-living soil bacteria that forms symbiotic relationships with non-leguminous host plants. Thus, on the roots of non-leguminous plants, Frankia generates nitrogen-fixing nodules.
Rhizobium is a bacterium that lives in the rhizosphere of the host plant. The rhizobium only acts in the non-legume root endosymbiosis Parasponia.
Klebsiella is a bacterium that fixes the majority of nitrogen in the atmosphere. This bacteria is found in the environment with non-leguminous plants.
Associative symbiotic nitrogen-fixing bacteria examples:
Associative symbiotic nitrogen-fixing bacteria are free-living bacteria that can cling to the roots of grasses and cereals as part of the associative symbiotic process.
Azospirillum is a Gram-negative bacteria that are microaerophilic. It lives in close proximity to the host plant root, where it fixes nitrogen from the air and acts as a symbiotic nitrogen-fixing bacteria.
The genus Gluconobacter belongs to the Rhodospirillales order of bacteria. It’s a Gram-variable bacteria, but it’s almost certainly gram-negative. It is a nitrogen-fixing bacteria that form nodules in leguminous plants in an associative symbiotic relationship.
Acetobacter is a bacteria that fix nitrogen. It finds a home in specialized structures on the roots of plants. Only when these bacteria are present within the nodules can they fix nitrogen.
Herbaspirillum is a symbiotic nitrogen-fixing bacteria that work in partnerships. It is more effective than rhizosphere bacteria at allowing plants to survive in nitrogen-deficient soils.
Azoarcus is a nitrogen-fixing bacteria with an associative symbiotic relationship. It interacts with plant root nodules, which fix atmospheric nitrogen in the soil and provide all usable nitrogen for the host plant’s growth. It associates with the host plant root nodules without inflicting any damage to the host plant.
To sum up our study, these nitrogen-fixing bacteria are extremely useful for maintaining environmental nitrogen levels. These nitrogen-fixing bacteria assist the plant in obtaining a sufficient amount of atmospheric nitrogen for growth and nourishment. All of the nitrogen-fixing bacteria mentioned above are involved in the nitrogen-fixation process, which benefits plants, animals, humans, and the environment.