Azospirillum/Azotobacter,Rhizobium.
They enrich soil nutrient/nitrogen fixation.
Detailed Answer:
Rhizobium leguminosarum is a symbiotic bactelium found in the root nodules of leguminous plants that has the ability to fix atmospheric nitrogen.
Azospirillum and Azotobacter are free-living bacteria found in the soil. They enrich soil with the nitrogen contents.
