title: Diversity of nitrogen-fixing bacteria associated with switchgrass in the native tallgrass prairie of northern Oklahoma.
abstract: Switchgrass (Panicum virgatum L.) is a perennial C4 grass native to North America that is being developed as a feedstock for cellulosic ethanol production. Industrial nitrogen fertilizers enhance switchgrass biomass production but add to production and environmental costs. A potential sustainable alternative source of nitrogen is biological nitrogen fixation. As a step in this direction, we studied the diversity of nitrogen-fixing bacteria (NFB) associated with native switchgrass plants from the tallgrass prairie of northern Oklahoma (United States), using a culture-independent approach. DNA sequences from the nitrogenase structural gene, nifH, revealed over 20 putative diazotrophs from the alpha-, beta-, delta-, and gammaproteobacteria and the firmicutes associated with roots and shoots of switchgrass. Alphaproteobacteria, especially rhizobia, predominated. Sequences derived from nifH RNA indicated expression of this gene in several bacteria of the alpha-, beta-, delta-, and gammaproteobacterial groups associated with roots. Prominent among these were Rhizobium and Methylobacterium species of the alphaproteobacteria, Burkholderia and Azoarcus species of the betaproteobacteria, and Desulfuromonas and Geobacter species of the deltaproteobacteria.
authors.affiliation: Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma, USA.
authors.forename: Rahul A
authors.initials: RA
authors.lastname: Bahulikar
authors.affiliation: Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma, USA.
authors.forename: Ivone
authors.initials: I
authors.lastname: Torres-Jerez
authors.affiliation: Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Worley
authors.affiliation: Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma, USA.
authors.forename: Kelly
authors.initials: K
authors.lastname: Craven
authors.affiliation: Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma, USA mudvardi@noble.org.
authors.forename: Michael K
authors.initials: MK
authors.lastname: Udvardi
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D058448:Biota; D065948:Grassland; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D009825:Oklahoma; D010088:Oxidoreductases / Q000235:genetics; D008897:Panicum / Q000382:microbiology*; D017422:Sequence Analysis, DNA
chemical_list: D010088:Oxidoreductases; C029130:nitrogenase reductase