title: Microbial community structure and functional diversity of nitrogen-fixing bacteria associated with Colophospermum mopane.
abstract: Colophospermum mopane is an indigenous legume tree that grows in Southern Africa and is one of the predominant trees of the woodland vegetation. In order to increase knowledge about its ecology, especially how C. mopane thrives in the nitrogen-poor soils of the region, we analyzed the root-associated bacteria to assess the active diazotrophic diversity and total microbial diversity by culture-dependent and independent techniques. Root nodules were not detected but in some samples the lateral roots showed an outgrowth-like protuberance, that were not likely to have functions related to legume root nodules. The bacterial isolates recovered were related to Actinobacteria, Firmicutes and Proteobacteria. The total microbial diversity was dominated by Actinobacteria-related phylotypes, while the active diazotrophic diversity showed that the majority of the sequences were related to the order Rhizobiales but also to Spirochaetes, Firmicutes, Bacteroidetes and Deltaproteobacteria. Several isolates showed characteristics of plant growth-promoting bacteria. These findings increase the spectrum of possible phylotypes that can be found in legume trees that are typically nodulated by Alpha- and Betaproteobacteria, and reveal for the first time a surprising diversity of nitrogen-fixing bacteria active in legume tree roots.
authors: Department of Microbe-Plant Interactions, Center for Biomolecular Interactions Bremen (CBIB), Faculty of Biology and Chemistry, University of Bremen, PO. Box 330440, D-28334 Bremen, Germany.
authors: Claudia Sofía
authors: CS
authors: Burbano
authors: Department of Microbe-Plant Interactions, Center for Biomolecular Interactions Bremen (CBIB), Faculty of Biology and Chemistry, University of Bremen, PO. Box 330440, D-28334 Bremen, Germany.
authors: Jann Lasse
authors: JL
authors: Grönemeyer
authors: Department of Microbe-Plant Interactions, Center for Biomolecular Interactions Bremen (CBIB), Faculty of Biology and Chemistry, University of Bremen, PO. Box 330440, D-28334 Bremen, Germany.
authors: Thomas
authors: T
authors: Hurek
authors: Department of Microbe-Plant Interactions, Center for Biomolecular Interactions Bremen (CBIB), Faculty of Biology and Chemistry, University of Bremen, PO. Box 330440, D-28334 Bremen, Germany breinhold@uni-bremen.de.
authors: Barbara
authors: B
authors: Reinhold-Hurek
mesh_terms: D039903:Actinobacteria / Q000235:genetics* / Q000302:isolation & purification; D000353:Africa, Southern; D015373:Bacterial Typing Techniques; D041963:Bacteroidetes / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D044822:Biodiversity; D004269:DNA, Bacterial / Q000235:genetics; D007887:Fabaceae / Q000382:microbiology*; D009586:Nitrogen Fixation / Q000502:physiology; D018517:Plant Roots / Q000382:microbiology*; D020560:Proteobacteria / Q000235:genetics* / Q000302:isolation & purification; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012987:Soil; D012988:Soil Microbiology
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012987:Soil
keywords: endophytes; expression; nitrogenase gene