Question

What happens to nitrogen during the process of denitrification?

Answer 1

Hint: Denitrification is facilitated by heterotrophic microbes like Pseudomonas denitrificans and autotrophic microbes like Thiobacillus denitrificans.
Several species are used to represent the reactions of denitrification.

Complete answer:
Denitrification is the process of reduction of nitrate ($NO^{3-}$) to nitrogen ($N_2$) with the production of a series of intermediate gaseous products. Denitrification is a process facilitated by microbes.
Microbes that facilitate denitrification require very little amounts of oxygen and carbon for energy. They can function with an oxygen concentration of less than $10\%$. The process of denitrification can leak $N_{2}$O into the atmosphere which acts as a greenhouse gas. This has a heavy influence on global warming.
Denitrification is performed by mostly heterotrophic bacteria with some autotrophic bacteria carrying out the process too.
The reactions that take place during the process of denitrification are as follows:
- ${NO}_{3}^{-}+ 2 {H}^{+} + 2 {e}^{-}→ {NO}_{2}^{-} +{H}_{2}O$
Catalyzing enzyme: Nitrate reductase
- ${NO}_{2}^{-}+ 2 {H}^{+} + {e}^{-}→ {NO} +{H}_{2}O$
Catalyzing enzyme: Nitrate reductase
- $2 {NO} + 2 {H}^{+} + 2 {e}^{-}→ {N}_{2}{O} +{H}_{2}O$
Catalyzing enzyme: Nitric oxide reductase
- ${N}_{2}{O} + 2 {H}^{+} + 2 {e}^{-}→ {N}_{2} +{H}_{2}O$
Catalyzing enzyme: Nitrous oxide reductase

The complete reaction of denitrification can be expressed as follows:
- $2 {NO}_{3}^{-}+ 12 {H}^{+} + 10 {e}^{-}→ {N}_{2} + 6 {H}_{2}O$

Note:
Denitrification can take place in environments like terrestrial and marine environments. Denitrification typically occurs in regions with a lack of oxygen.
The process of denitrification is commonly used in sewage plants to remove nitrogenous waste from municipal waters.