Three distinct clades of cultured heterocystous cyanobacteria constitute the dominant N2-fixing members of biological soil crusts of the Colorado Plateau, USA

Chris M. Yeager, Jennifer L. Kornosky, Rachael E. Morgan, Elizabeth C. Cain, Ferran Garcia-Pichel, David C. Housman, Jayne Belnap, Cheryl R. Kuske

Research output: Contribution to journalArticlepeer-review

80 Scopus citations

Abstract

The identity of the numerically dominant N2-fixing bacteria in biological soil crusts of the Colorado Plateau region and two outlying areas was determined using multiple approaches, to link the environmental diversity of nifH gene sequences to cultured bacterial isolates from the regions. Of the nifH sequence-types detected in soil crusts of the Colorado Plateau, 89% (421/473) were most closely related to nifH signature sequences from cyanobacteria of the order Nostocales. N2-fixing cyanobacterial strains were cultured from crusts and their morphotypes, 16S rRNA gene and nifH gene sequences were characterized. The numerically dominant diazotrophs in the Colorado Plateau crusts fell within three clades of heterocystous cyanobacteria. Two clades are well-represented by phylogenetically and morphologically coherent strains, corresponding to the descriptions of Nostoc commune and Scytonema hyalinum, which are widely recognized as important N2-fixing components of soil crusts. A third, previously-overlooked clade was represented by a phylogenetically coherent but morphologically diverse group of strains that encompass the morphogenera Tolypothrix and Spirirestis. Many of the strains in each of these groups contained at least two nifH copies that represent different clusters in the nifH environmental survey.

Original languageEnglish (US)
Pages (from-to)85-97
Number of pages13
JournalFEMS microbiology ecology
Volume60
Issue number1
DOIs
StatePublished - Apr 2007

Keywords

  • Biological soil crust
  • Cyanobacteria
  • Nitrogen fixation
  • Nostoc
  • Scytonema
  • nifH

ASJC Scopus subject areas

  • Microbiology
  • Ecology
  • Applied Microbiology and Biotechnology

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