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The nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the ...
Nitrogen cycle. Nitrification is the biological oxidation of ammonia to nitrate via the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil. The process of complete nitrification may occur through separate organisms [1] or entirely within one organism, as in comammox bacteria. The transformation of ammonia to ...
Nitrogen fixation is essential to life on Earth because fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen-containing organic compounds such as amino acids, polypeptides and proteins, nucleoside triphosphates and nucleic acids.
Nitrifying bacteria then convert this ammonium into nitrate by oxidation, which can then be used by plants to create more proteins thus completing the nitrogen cycle. [6] This process is called nitrification. Energy from this oxidation reaction can also be used to synthesize organic compounds in a process called chemosynthesis. [7]
Nitrogen is a fundamental chemical component of amino acids, the molecular building blocks of protein. As such, nitrogen balance may be used as an index of protein metabolism. [1] When more nitrogen is gained than lost by an individual, they are considered to have a positive nitrogen balance and be in a state of overall protein anabolism.
Most of the nitrogen taken up by plants is from the soil in the forms of NO − 3, although in acid environments such as boreal forests where nitrification is less likely to occur, ammonium NH + 4 is more likely to be the dominating source of nitrogen. [49] Amino acids and proteins can only be built from NH + 4, so NO − 3 must be reduced.
The only major component of most food which contains nitrogen is protein (fat, carbohydrate and dietary fiber do not contain nitrogen). If the amount of nitrogen is multiplied by a factor depending on the kinds of protein expected in the food the total protein can be determined. This value is known as the "crude protein" content.
The preferred nitrogen electron acceptors in order of most to least thermodynamically favorable include nitrate (NO 3 −), nitrite (NO 2 −), nitric oxide (NO), nitrous oxide (N 2 O) finally resulting in the production of dinitrogen (N 2) completing the nitrogen cycle. Denitrifying microbes require a very low oxygen concentration of less than ...