nifH gene diversity in the bacterial community associated with the rhizosphere of Molinia coerulea, an oligonitrophilic perennial grass.
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.
Hamelin
Jérôme
J
Laboratoire de Microbiologie, Université de Neuchâtel, Case Postale 2, CH-2007 Neuchâtel, Switzerland. jerome.hamelin@unine.ch
Fromin
Nathalie
N
Tarnawski
Sonia
S
Teyssier-Cuvelle
Sylvie
S
Aragno
Michel
M
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
D010088:Oxidoreductases; C029130:nitrogenase reductase