Which of the following bacteria can fix atmospheric nitrogen in free state? |
Rhizobium Azospirillum Azotobacter Both II and III |
Both II and III |
a- Rhizobium b- Azospirillum c- Azotobacter d- Both II and III are correct answer. Bacteria can fix atmospheric nitrogen while free-living in the soil (examples Azospirillum and Azotobacter), thus enriching the nitrogen content of the soil. Rhizobium, on the other hand, is a bacteria that forms a symbiotic relationship with leguminous plants, forming nodules on their roots and fixing nitrogen in the root nodules. It does not fix atmospheric nitrogen in a free-living state. |