Q8: Which of the following is/are the example of nitrifying bacteria? - Soil Fertility, Classification, Remote Sensing, Soil Biology, Fertilizers & Pollution - ICAR AIEEA PG 2024 - Physical Science | Agrigyan

Nitrification is a biological two-step aerobic oxidation of ammonium ($\text{NH}_4^+$) to nitrate ($\text{NO}_3^-$):

• Ammonia oxidation: $\text{NH}_4^+ + \frac{3}{2}\text{O}_2 \rightarrow \text{NO}_2^- + \text{H}_2\text{O} + 2\text{H}^+$ (catalyzed by obligate autotrophs like Nitrosomonas, Nitrosococcus, Nitrosospira).
• Nitrite oxidation: $\text{NO}_2^- + \frac{1}{2}\text{O}_2 \rightarrow \text{NO}_3^-$ (catalyzed by Nitrobacter, Nitrospina, and Nitrospira).
  Complete ammonia oxidation (Comammox) carried out by certain Nitrospira species oxidizes ammonia directly to nitrate.