Write the name of a bio-fertilizer.

(N/A) bio-fertilizer is a substance that contains living microorganisms which,when applied to seeds,plant surfaces,or soil,colonize the rhizosphere or the interior of the plant and promote growth by increasing the supply or availability of primary nutrients to the host plant.
Examples of bio-fertilizers include $Rhizobium$,$Azotobacter$,$Azospirillum$,and Blue-Green Algae (Cyanobacteria) like $Anabaena$ and $Nostoc$.