Question

The denitrifying bacteria are
(a) Micrococcus denitrificans
(b) Pseudomonas
(c) Thiobacillus
(d) All of the above

Answer 1

Hint: Facultative anaerobic organisms that help in the conversion of nitrates into atmospheric nitrogen by utilizing nitrates as final electron transport acceptors in presence of enzymes nitrate reductase, nitric oxide reductase, and nitrous oxide reductase.

Complete step by step answer:
The organisms that convert nitrates present in the soil into atmospheric nitrogen which causes depletion of soil fertility and thereby reduces agricultural productivity. Some of the examples of organisms that perform denitrification are pseudomonas, Micrococcus denitrificans, etc.

Additional information:
- The diverse group of bacteria that belongs to various phyla together with algae and organisms belonging to archaea perform denitrification which is an important process in the nitrogen cycle.
-The organisms that perform denitrification utilizes oxidized nitrogen as a final electron acceptor
- They exhibit great diversity with 50 genera and 125 different species which comprises 10-15% of the bacteria population in both land and water.
- The majority of these organisms are facultative aerobic heterotrophs.
- In the presence of oxygen they use oxygen as the final electron acceptor and in the absence of oxygen, they immediately switch to anaerobic and use nitrates as a final electron acceptor.
- These bacteria convert nitrates into atmospheric nitrogen by using enzymes such as nitrate reductase, nitric oxide reductase, and nitrous oxide reductase.
- Proteobacteria that belong to alpha and gamma strains perform denitrification
${ 2NH }_{ 3 }+{ 3O }_{ 2 }\xrightarrow { } { 2NO }_{ 2 }^{ - }+{ 2H }_{ 2 }O\\ { 2NO }_{ 2 }^{ - }+{ O }\xrightarrow { } { 2NO }_{ 3 }^{ - }$.
This is the most common process in denitrification.
So, the correct answer is ‘all of the above’.

Note: Anaerobic denitrification was first observed in the year 2008 during the isolation of methane by methyl oxidizing bacteria.
Denitrification is one of the important processes in the nitrogen cycle.
Methane is one of the important greenhouse gases. This denitrifying bacteria also helps in the oxidation of methane into carbon dioxide water and energy.