Which of the following can be used as a biofertilizer and enrich soil with nitrogen?

Bacteria can fix atmospheric nitrogen while free-living in the soil (examples Azospirillum and Azotobacter), thus enriching the nitrogen content of the soil.
Agrobacterium, Acetobacter and Glomus do not help in nitrogen fixation. Glomus form mycorrhiza. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant.