Question

Explain how Nitrification is different from Nitrogen fixation. Mention the role of Thiobacillus in the Nitrogen cycle? What do you understand by biological Nitrogen fixation?

Answer 1

Nitrification is the biological oxidation or conversion of ammonia to nitrite and further oxidation of nitrite to nitrate. The conversion of ammonia to nitrite is usually the rate-limiting step of nitrification. The process by which molecular nitrogen in the air is converted into ammonia or other nitrogenous compounds in the soil is called nitrogen fixation.

Complete answer: The growth of almost all organisms depends on the availability of nitrogen with amino acids. It must be in the fixed form of ammonia or nitrate ions to be used for the growth of organisms. Generally reduced forms of nitrogen are preferred mostly by plants. A combination of atoms occurs for the requirement of substantial amounts of energy. Biological nitrogen fixation is not used for the large scale operations of nitrogen. The aerobic process performed by small groups of autotrophic bacteria and archaea is called nitrification. A relatively unreactive molecule that is metabolically useless to all but a few microorganisms is called molecular dinitrogen (atmospheric nitrogen). The conversion of nitrogen into ammonia, which is metabolized by most organisms is called biological nitrogen fixation. When atmospheric nitrogen is converted to ammonia by the presence of a nitrogenase enzyme, the biological nitrogen fixation takes place. The process is doubled to the hydrolysis of 16 equivalents of Adenosine Triphosphate and is followed by the co-formation of one equivalent of Hydrogen. The conversion of Nitrogen into ammonia happens at a metal cluster known as the iron-molybdenum cofactor. The mechanism occurs through a series of protonation and reduction steps.

Note: Nitrogen fixation is essential to life because fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen-containing organic compounds, such as amino acids and proteins, nucleoside triphosphates, and nucleic acids.