What is Nitrification?

Nitrification is the process by which ammonia is converted into nitrites (NO^2-) and further to nitrates (NO^3-) by nitrifying bacteria. This salts can be easily utilised by plants.

NH₄⁺(Ammonium) → NO^2- (Nitrite) → NO^3- (Nitrate).

Mechanism of Nitrification

Mechanism of Nitrification includes two main stages.

• Oxidation of Ammonia to Nitrate
• Oxidation of Nitrate to Nitrites

Nitrification begins with the oxidation of ammonia to nitrites, a process catalysed by ammonia-oxidising bacteria (AOB). These bacteria utilise ammonia as an energy source and produce nitrites as a byproduct. This step is catalysed by ammonium monooxygenase The next step involves the oxidation of nitrites to nitrates, facilitated by nitrite-oxidising bacteria (NOB). This reaction is catalysed by nitrite oxidoreductase. These bacteria complete the conversion of ammonia to nitrates, making it available for uptake by plants and thereby nitrogen is fixed in the living world and further transferred through the nitrogen cycle.

Nitrifying Bacteria

Nitrifying bacteria are classified into:

• Ammonia-Oxidizing Bacteria (AOB): AOB are bacteria that initiate the nitrification process by oxidising ammonia to nitrites. Examples of AOB include species belonging to the genera Nitrosomonas and Nitrosospira.
• Nitrite-Oxidizing Bacteria (NOB): NOB are bacteria that further oxidise nitrites produced by AOB into nitrates. Examples of NOB include species belonging to the genera Nitrobacter and Nitrospira.

Significance of Nitrification

Nitrification is an important process in the nitrogen cycle in the ecosystem:

• Nutrient Source of Plant: Nitrification converts ammonia (NH₃), which is often toxic to plants, into nitrate (NO^3-) form, which is the primary source of nitrogen for plant nutrition. Nitrate is readily taken up by plants and used to synthesise amino acids, proteins, and other essential molecules.
• Increase Agricultural Yield: Nitrates play an important role in plant nutrition as it is a major nutrient.
• Increase Soil Fertility: Nitrification replenishes soil nitrogen, maintaining soil fertility over time.
• Maintain Water Quality: Nitrification regulates ammonia in aquatic environments and thereby reduces eutrophication or algal bloom.
• Important in Wastewater Treatment: In sewage treatment plants, nitrifying bacteria are utilised to convert ammonia present in wastewater into nitrate, which can then be further processed or removed, reducing environmental pollution.

Difference Between Nitrification and Denitrification: Nitrification and Denitrification are two main stages in the Nitrogen cycle. Molecular nitrogen cannot be utilized directly by plants so it is fixed in the form of nitrites and nitrates with the help of specialized bacteria. Nitrogen recycling is done with the Nitrogen cycle. Stages include- Nitrogen fixation, Nitrification, Assimilation, Ammonification and Denitrification.

Nitrification is the process of converting ammonia to nitrite and then nitrate with the help of nitrifying bacteria. It is an oxidation process that works under aerobic conditions. Denitrification, on the other hand, is a reduction process that converts nitrate into nitrogen gas and works under anaerobic conditions. In this article, we will look into the difference between nitrification and denitrification, its mechanism, and its significance.