Question

Nif gene is found in
A) Pseudomonas
B) Salmonella
C) Rhizobium
D) Mycobacterium

Answer 1

Hint:We shall first discuss what are nif genes and its specifications.Nif genes are the genes that contain the enzymes which are responsible for the conversion of atmospheric nitrogen into other forms of nitrogen like ammonia which are utilized by organisms.

Complete Answer:
Nif genes contain an enzyme nitrogenase which is responsible for the conversion of nitrogen. It also contains several proteins that help in nitrogen fixation.
>Root nodules are the special type of organs formed by a rod shaped, gram negative, motile bacteria called Rhizobium for nitrogen fixation.
>Nitrates are reduced to nitrogen with the help of denitrifying bacteria called pseudomonas and nitrogenase enzymes have no role in it.
>Salmonella is a rod shaped, gram negative bacteria. It is a human pathogenic bacteria that is found in the human intestine. It is not involved in nitrogen fixation.
>Mycobacterium is also a human pathogenic bacteria that causes tuberculosis. Nitrogenase enzyme is absent and it has no role in nitrogen fixation.

Hence the correct answer is option (c)Rhizobium.

Note:Remember that nif genes are also present in cyanobacteria. Rhizobium is associated with the root nodules for nitrogen fixation, but cyanobacteria has the symbiotic association with the plants in the process of nitrogen fixation