Search results for "diazotroph"
showing 10 items of 10 documents
Methanotrophs are core members of the diazotroph community in decaying Norway spruce logs
2018
Dead wood is initially a nitrogen (N) poor substrate, where the N content increases with decay, partly due to biological N2 fixation, but the drivers of the N accumulation are poorly known. We quantified the rate of N2 fixation in decaying Norway spruce logs of different decay stages and studied the potential regulators of the N2-fixation activity. The average rate for acetylene reduction in the decaying wood was 7.5 nmol ethylene g−1d−1, which corresponds to 52.9 μg N kg−1d−1. The number of nifH copies (g−1 dry matter) was higher at the later decay stages, but no correlation between the copy number and the in vitro N2 fixation rate was found. All recovered nifH sequences were assigned to t…
The influence of oxygen and methane on nitrogen fixation in subarctic Sphagnum mosses
2018
Biological nitrogen fixation is an important source of bioavailable nitrogen in Sphagnum dominated peatlands. Sphagnum mosses harbor a diverse microbiome including nitrogen-fixing and methane (CH4) oxidizing bacteria. The inhibitory effect of oxygen on microbial nitrogen fixation is documented for many bacteria. However, the role of nitrogen-fixing methanotrophs in nitrogen supply to Sphagnum peat mosses is not well explored. Here, we investigated the role of both oxygen and methane on nitrogen fixation in subarctic Sphagnum peat mosses. Five species of Sphagnum mosses were sampled from two mesotrophic and three oligotrophic sites within the Lakkasuo peatland in Orivesi, central Finland. Mo…
2020
The rapid developments in the next-generation sequencing methods in the recent years have provided a wealth of information on the community structures and functions of endophytic bacteria. However, the assembly processes of these communities in different plant tissues are still currently poorly understood, especially in wild plants in natural settings. The aim of this study was to compare the composition of endophytic bacterial communities in leaves and roots of arcto-alpine pioneer plant Oxyria digyna, and investigate, how plant tissue (leaf or root) or plant origin affect the community assembly. To address this, we planted micropropagated O. digyna plants with low bacterial load (bait pla…
Global distributions of diazotrophs abundance and biomass - Depth integrated values computed from a collection of source datasets - Contribution to t…
2013
The MAREDAT atlas covers 11 types of plankton, ranging in size from bacteria to jellyfish. Together, these plankton groups determine the health and productivity of the global ocean and play a vital role in the global carbon cycle. Working within a uniform and consistent spatial and depth grid (map) of the global ocean, the researchers compiled thousands and tens of thousands of data points to identify regions of plankton abundance and scarcity as well as areas of data abundance and scarcity. At many of the grid points, the MAREDAT team accomplished the difficult conversion from abundance (numbers of organisms) to biomass (carbon mass of organisms). The MAREDAT atlas provides an unprecedente…
Global distributions of diazotrophs Gamma-A nifH genes abundance - Depth integrated values computed from a collection of source datasets - Contributi…
2013
The MAREDAT atlas covers 11 types of plankton, ranging in size from bacteria to jellyfish. Together, these plankton groups determine the health and productivity of the global ocean and play a vital role in the global carbon cycle. Working within a uniform and consistent spatial and depth grid (map) of the global ocean, the researchers compiled thousands and tens of thousands of data points to identify regions of plankton abundance and scarcity as well as areas of data abundance and scarcity. At many of the grid points, the MAREDAT team accomplished the difficult conversion from abundance (numbers of organisms) to biomass (carbon mass of organisms). The MAREDAT atlas provides an unprecedente…
Spatial segregation of the biological soil crust microbiome around its foundational cyanobacterium, Microcoleus vaginatus, and the formation of a nit…
2019
12 pages; International audience; Background Biological soil crusts (biocrusts) are a key component of arid land ecosystems, where they render critical services such as soil surface stabilization and nutrient fertilization. The bundle-forming, filamentous, non-nitrogen-fixing cyanobacterium Microcoleus vaginatus is a pioneer primary producer, often the dominant member of the biocrust microbiome, and the main source of leaked organic carbon. We hypothesized that, by analogy to the rhizosphere of plant roots, M. vaginatus may shape the microbial populations of heterotrophs around it, forming a specialized cyanosphere. Results By physically isolating bundles of M. vaginatus from biocrusts, we …
Nitrogen fixation and methanotrophy in forest mosses along a N deposition gradient
2013
Abstract Nitrogen deposition has decreased the plant-associated nitrogen (N 2 ) fixation when measured using the indirect acetylene reduction assay (ARA). However, nitrogen deposition can also lead to changes in the diversity of moss symbionts, e.g. affect methanotrophic N 2 fixation, which is not measured by ARA. To test this hypothesis we compared ARA with the direct stable isotope method ( 15 N 2 incorporation) and studied methanotrophy in two mosses, Hylocomium splendens and Pleurozium schreberi , collected from seven forest sites along a boreal latitudinal N deposition transect. We recognized that the two independent N 2 fixation measures gave corresponding results with the conversion …
Biological nitrogen fixation for the 21st century
1998
The biodiversity of nitrogen-fixing organisms is huge. Taxonomic and phylogenetic research is needed to structure this diversity, to facilitate communication among scientists, and to increase our understanding of the evolution and biology of diazotrophs. Molecular tools for taxonomic and biodiversity studies of diazotrophic rhizobia, frankiae, cyanobacteria and bacilli are presented in sections 2 to 5. Sections 6 to 9 focus on problems with genus and species assignment.