Question

The bacteria which convert nitrate on molecular nitrogen are called

• A. nitrifying bacteria
• B. methanobacteria
• C. diazotrophic bacteria
• D. denitrifying bacteria

Answer 1

Answer: (D)

Certain anaerobic bacteria, which include some species of Pseudomonas, Moraxella, Spirillum, Thiobacillus and Bacillus are able to reduce nitrates to nitrites, nitrites to nitrous oxide gas $(N_{2}O)$ and subsequently to molecules nitrogen. This conversion of nitrates to $N_{2}O$ or $N_2$ is called denitrification. Soil fertility is greatly reduced because of the depletion of nitrogen available to plants.