Nitrogen Fertilization Reduces Nitrogen Fixation Activity of Diverse Diazotrophs in Switchgrass Roots

The use of synthetic nitrogen fertilizers to grow biofuel crops adds the economic and environmental costs biomass production. Biological fixation provides an alternative, eco-friendly source for leguminous plants some nonlegumes. With objective characterizing eventually harnessing nitrogen-fixing bacteria in switchgrass roots, we assayed nitrogenase activity surveyed nifH-expressing roots grown under agricultural conditions. Plants were cultivated at two separate locations Oklahoma different soil types 5 years with three fertilizer regimes (0, 90, 180 kg N ha ?1 year ). Nitrogenase associated cleaned was found be highest no lowest or not detectable level fertilizer. A total 454 abundant nifH operational taxonomic units (OTUs) identified roots. Diversity analysis active showed that most common orders Burkholderiales (171 OTUs), Desulfovibrionales (55 Rhizobiales (44 OTUs). OTUs belonging Azonexus, Pseudacidovorax, Desulfovibrio, Dechloromonas, Bradyrhizobium enriched low Analysis significant distinct microbial communities field locations, as well a unique community unfertilized Frederick exhibited rates fixation. [Formula: see text] Copyright © 2021 Author(s). This is open access article distributed CC BY-NC-ND 4.0 International license .