title: nifH gene diversity in the bacterial community associated with the rhizosphere of Molinia coerulea, an oligonitrophilic perennial grass.
abstract: Rhizosphere associative dinitrogen fixation could be a valuable source of nitrogen in many nitrogen limited natural ecosystems, such as the rhizosphere of Molinia coerulea, a hemicryptophytic perennial grass naturally occurring in contrasted oligonitrophilic soils. The diversity of the dinitrogen-fixing bacteria associated with this environment was assessed by a cloning-sequencing approach on the nifH gene directly amplified from environmental DNA extracts. Seventy-seven randomly picked clones were analysed. One type of NifH sequence was dominant in both roots and surrounding soil, and represented 56% of all retrieved sequences. This cluster included previously described environmental clones and did not contain any NifH sequences similar to cultivated diazotrophs. The predominance of few NifH sequence types in the roots and the rhizosphere of Molinia coerulea indicate that the plant environment mediates a favourable niche for such dinitrogen-fixing bacteria.
authors.affiliation: Laboratoire de Microbiologie, Université de Neuchâtel, Case Postale 2, CH-2007 Neuchâtel, Switzerland. jerome.hamelin@unine.ch
authors.forename: Jérôme
authors.initials: J
authors.lastname: Hamelin
authors.forename: Nathalie
authors.initials: N
authors.lastname: Fromin
authors.forename: Sonia
authors.initials: S
authors.lastname: Tarnawski
authors.forename: Sylvie
authors.initials: S
authors.lastname: Teyssier-Cuvelle
authors.forename: Michel
authors.initials: M
authors.lastname: Aragno
mesh_terms: D005798:Genes, Bacterial; D014644:Genetic Variation; D009586:Nitrogen Fixation / Q000235:genetics; D010088:Oxidoreductases / Q000235:genetics*; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology*; D006109:Poaceae / Q000382:microbiology*; D012230:Rhizobiaceae / Q000235:genetics* / Q000378:metabolism; D012988:Soil Microbiology
chemical_list: D010088:Oxidoreductases; C029130:nitrogenase reductase