Answer:
Nitrogen-fixing bacteria
Explanation:
These type of bacteria living in the soil or symbiotic interaction with root plants has the ability to transform the atmospheric nitrogen (N2) into ammonia (NH3), in this form many organisms like plants can metabolise. Bacterial genera like Azotobacter spp., Rhizobium spp., Azospirilum spp., etc. can make the transformation of nitrogen by specialized enzymes called nitrogenases.