Importance of bacteria in Nitrogen cycle

Bacteria are essential in the nitrogen cycle because they play a crucial role in converting atmospheric nitrogen gas (N2) into a form that can be used by plants and other organisms. Nitrogen gas is abundant in the atmosphere, but most living organisms cannot use it directly. Bacteria that are able to convert N2 gas into ammonia (NH3) through a process called nitrogen fixation, provide an important source of nitrogen for plants.

In addition to nitrogen fixation, other bacteria in the nitrogen cycle play important roles in converting ammonia into nitrite (NO2) and then into nitrate (NO3), which are forms of nitrogen that can be readily absorbed by plants. This process is called nitrification, and it is critical in making nitrogen available to plants for growth and development.

Furthermore, bacteria also play a role in the final step of the nitrogen cycle, called denitrification. Denitrifying bacteria convert nitrate back into atmospheric nitrogen gas, which helps to maintain a balance of nitrogen in the environment.

Therefore, bacteria are a necessary part of the nitrogen cycle as they are responsible for converting and recycling nitrogen between different forms that can be used by plants and other organisms. Without bacteria, nitrogen would remain locked in its atmospheric form and unavailable to living organisms, ultimately impacting the entire ecosystem.

What is nitrogen cycle?

The nitrogen cycle is a biogeochemical cycle that describes how nitrogen moves and transforms in the environment. Nitrogen is necessary for life, but it must be converted into different forms before different organisms can use it. The nitrogen cycle involves a series of processes that transform nitrogen from one form to another and move it through the atmosphere, the soil, and the water.

Nitrogen cycle steps

The following are the main steps of the nitrogen cycle:

Nitrogen Fixation

The first step in the nitrogen cycle is nitrogen fixation, which is the process of converting atmospheric nitrogen gas (N2) into a form of nitrogen that plants and other organisms can use, such as ammonium (NH4+) or nitrate (NO3). This process is carried out by nitrogen-fixing bacteria, which live in the soil or in symbiotic relationships with plants.


The next step in the nitrogen cycle is nitrification, which is the process of converting ammonium into nitrite (NO2) and then into nitrate by nitrifying bacteria. Nitrate is the most common form of nitrogen used by plants.


In assimilation, plants take up the nitrogen compounds, such as ammonium and nitrate, and incorporate them into their own organic molecules, such as proteins and DNA.


Nitrogen compounds from dead plants and animals are converted back into ammonium by decomposer bacteria such as fungi and bacteria during ammonification.


Denitrification is the final step in the nitrogen cycle, in which denitrifying bacteria convert nitrate back into atmospheric nitrogen gas (N2) or nitrous oxide (N2O), which is released into the atmosphere. This process occurs in oxygen-poor environments, such as wetlands, soils, and sediments.

The nitrogen cycle is critical for the survival of living organisms and the maintenance of ecosystem balance. It is essential for plant growth and the production of food for animals and humans.

Nitrogen cycle diagram

Image by storyset on Freepik

How is the nitrogen cycle important to humans?

The nitrogen cycle is important to humans because it provides a continuous supply of nitrogen to plants, which are the primary source of food for humans and animals. Nitrogen is a vital component of DNA, RNA, and proteins, which are essential for the growth and development of living organisms. Therefore, a sufficient supply of nitrogen is critical for maintaining healthy ecosystems and for ensuring food security.

In agriculture, farmers use nitrogen fertilizers to provide plants with the necessary nitrogen for growth. However, excessive use of nitrogen fertilizers can lead to environmental problems such as water pollution, greenhouse gas emissions, and soil degradation. Understanding the nitrogen cycle and how it works can help farmers to use fertilizers more efficiently, reduce waste, and protect the environment.

Furthermore, the nitrogen cycle is important in the wastewater treatment process. Bacteria are used in wastewater treatment facilities to convert nitrogen compounds into less harmful forms, allowing the water to be released into the environment. Proper wastewater treatment is critical for public health and environmental protection.

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Anuradhika Lakmali

Anuradhika Lakmali is a co-founder of Science A Plus learning network. She is working as a government teacher and has interest in chemistry, biology, phisics and self development.