Question

Nitrosomonas, Nitrococcus and Nitrobacter are involved in the process of

• A. Nitrate assimilation
• B. Denitrification
• C. Nitrification
• D. Ammonification

Answer 1

The correct option is C Nitrification

Nitrosomonas, Nitrococcus and Nitrobacter are nitrifying bacteria. Ammonia is first oxidized to nitrite by the bacteria Nitrosomonas and/or Nitrococcus.
The nitrite is further oxidized to nitrate with the help of the bacterium Nitrobacter. These steps are called nitrification.

In nitrification Nitrosomonas plays the role of oxidizing ammonia to nitrite, which is then converted to nitrate by other bacteria. Nitrosomonas and Nitrobacter are chemoautotrophic organisms found in soil and water, and are responsible for the oxidation of ammonium to nitrite (Nitrosomonas) and nitrite to nitrate (Nitrobacter).

The nitrification process requires the mediation of two distinct groups: bacteria that convert ammonia to nitrites (Nitrosomonas, Nitrosospira, Nitrosococcus, and Nitrosolobus) and bacteria that convert nitrites (toxic to plants) to nitrates (Nitrobacter, Nitrospina, and Nitrococcus).