Which of the Following Bacterial Genera Plays an Important Role

Question

Which of the following bacterial genera plays an important role in environmental nitrogen cycles?
A) Nitrobacter
B) Rhizobium
C) Azospirillum
D) both Nitrobacter and Rhizobium
E) Nitrobacter, Rhizobium, and Azospirillum

Accepted Answer

Nitrobacter is involved in the conversion of nitrite to nitrate in the process of nitrification, Rhizobium is involved in nitrogen fixation in the roots of leguminous plants, and Azospirillum is involved in nitrogen fixation in the soil. Therefore, all three genera play important roles in environmental nitrogen cycles.