The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Yuqing Zhang - One of the best experts on this subject based on the ideXlab platform.
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high diversity of Nitrogen Fixing Bacteria in the upper reaches of the heihe river northwestern china
Biogeosciences, 2013Co-Authors: T. Chen, W. Zhang, X. K. Wu, Haozhi Long, Binglin Zhang, Yuqing ZhangAbstract:Vegetation plays a key role in water conservation in the southern Qilian Mountains (northwestern China), located in the upper reaches of the Heihe River. Nitrogen-Fixing Bacteria are crucial for the protection of the Nitrogen supply for vegetation in the region. In the present study, nifH gene clone libraries were established to determine differences between the Nitrogen-Fixing Bacterial communities of the Potentilla parvifolia shrubland and the Carex alrofusca meadow in the southern Qilian Mountains. All of the identified Nitrogen-Fixing Bacterial clones belonged to the ProteoBacteria. At the genus level, Azospirillum was only detected in the shrubland soil, while Thiocapsa , Derxia , Ectothiorhodospira , Mesorhizobium , Klebsiella , Ensifer , Methylocella and Pseudomonas were only detected in the meadow soil. The phylogenetic tree was divided into five lineages: lineages I, II and III mainly contained nifH sequences obtained from the meadow soils, while lineage IV was mainly composed of nifH sequences obtained from the shrubland soils. The Shannon–Wiener index of the nifH genes ranged from 1.5 to 2.8 and was higher in the meadow soils than in the shrubland soils. Based on these analyses of diversity and phylogeny, the plant species were hypothesised to influence N cycling by enhancing the fitness of certain Nitrogen-Fixing taxa. The number of nifH gene copies and colony-forming units (CFUs) of the cultured Nitrogen-Fixing Bacteria were lower in the meadow soils than in the shrubland soils, ranging from 0.4 × 10 7 to 6.9 × 10 7 copies g −1 soil and 0.97 × 10 6 to 12.78 × 10 6 g −1 soil, respectively. Redundancy analysis (RDA) revealed that the diversity and number of the nifH gene copies were primarily correlated with aboveground biomass in the shrubland soil. In the meadow soil, nifH gene diversity was most affected by altitude, while copy number was most impacted by soil-available K. These results suggest that the Nitrogen-Fixing Bacterial communities beneath Potentilla were different from those beneath Carex .
V Salmeron - One of the best experts on this subject based on the ideXlab platform.
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liberation of amino acids by heterotrophic Nitrogen Fixing Bacteria
Amino Acids, 2005Co-Authors: J Gonzalezlopez, B Rodelas, C Pozo, V Salmeronlopez, M V Martineztoledo, V SalmeronAbstract:Large amounts of amino acids are produced by Nitrogen-Fixing Bacteria such as Azotobacter, Azospirillum, Rhizobium, Mesorhizobium and Sinorhizobium when growing in culture media amended with different carbon and Nitrogen sources. This kind of Bacteria live in close association with plant roots enhanced plant growth mainly as a result of their ability to fix Nitrogen, improving shoot and root development suppression of pathogenic Bacteria and fungi, and increase of available P concentration. Also, it has been strongly evidenced that production of biologically substances such as amino acids by these rhizoBacteria are involved in many of the processes that explain plant-grown promotion. This paper reviews literature concerning amino acids production by Nitrogen-Fixing Bacteria. The role of amino acids in microbial interactions in the rhizosphere and establishment of plant Bacterial association is also discussed.
T. Chen - One of the best experts on this subject based on the ideXlab platform.
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high diversity of Nitrogen Fixing Bacteria in the upper reaches of the heihe river northwestern china
Biogeosciences, 2013Co-Authors: T. Chen, W. Zhang, X. K. Wu, Haozhi Long, Binglin Zhang, Yuqing ZhangAbstract:Vegetation plays a key role in water conservation in the southern Qilian Mountains (northwestern China), located in the upper reaches of the Heihe River. Nitrogen-Fixing Bacteria are crucial for the protection of the Nitrogen supply for vegetation in the region. In the present study, nifH gene clone libraries were established to determine differences between the Nitrogen-Fixing Bacterial communities of the Potentilla parvifolia shrubland and the Carex alrofusca meadow in the southern Qilian Mountains. All of the identified Nitrogen-Fixing Bacterial clones belonged to the ProteoBacteria. At the genus level, Azospirillum was only detected in the shrubland soil, while Thiocapsa , Derxia , Ectothiorhodospira , Mesorhizobium , Klebsiella , Ensifer , Methylocella and Pseudomonas were only detected in the meadow soil. The phylogenetic tree was divided into five lineages: lineages I, II and III mainly contained nifH sequences obtained from the meadow soils, while lineage IV was mainly composed of nifH sequences obtained from the shrubland soils. The Shannon–Wiener index of the nifH genes ranged from 1.5 to 2.8 and was higher in the meadow soils than in the shrubland soils. Based on these analyses of diversity and phylogeny, the plant species were hypothesised to influence N cycling by enhancing the fitness of certain Nitrogen-Fixing taxa. The number of nifH gene copies and colony-forming units (CFUs) of the cultured Nitrogen-Fixing Bacteria were lower in the meadow soils than in the shrubland soils, ranging from 0.4 × 10 7 to 6.9 × 10 7 copies g −1 soil and 0.97 × 10 6 to 12.78 × 10 6 g −1 soil, respectively. Redundancy analysis (RDA) revealed that the diversity and number of the nifH gene copies were primarily correlated with aboveground biomass in the shrubland soil. In the meadow soil, nifH gene diversity was most affected by altitude, while copy number was most impacted by soil-available K. These results suggest that the Nitrogen-Fixing Bacterial communities beneath Potentilla were different from those beneath Carex .
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High diversity of Nitrogen-Fixing Bacteria in upper reaches of Heihe River, Northwestern China
Biogeosciences Discussions, 2013Co-Authors: T. Chen, W. Zhang, X. K. Wu, H. Z. Long, B. G. ZhangAbstract:Abstract. Vegetation plays a key role to water conservation in southern Qilian Mountains (Northwestern China), the upper reaches of Heihe River. Nitrogen-Fixing Bacteria are crucial for vegetation protection because they can supply plants with Nitrogen source. Nevertheless, little is known about Nitrogen-Fixing Bacteria in this region. In present study, nifH gene clone libraries were established for detecting the difference of Nitrogen-Fixing Bacterial communities between Potentilla parvifolia shrub and Carex alrofusca meadow in the southern Qilian Mountains. All the identified Nitrogen-Fixing Bacterial clones belonged to ProteoBacteria. At the genus level, the Azospirillum sp. was only detected in shrub soil while Thiocapsa sp., Derxiasp., Ectothiorhodospira sp., Mesorhizobium sp., Klebsiella sp., Ensifer sp., Methylocella sp. and Peseudomonas sp. were just detected in meadow soil. Shannon–Wiener index of nifH gene ranged from 1.5 to 2.8 and was higher in meadow soil than shrub soil. Contrarily, the nifH gene copies and CFUs of cultured Nitrogen-Fixing Bacteria ranged from 0.4 × 107 to 6.9 × 107 copies g−1 soil and 0.97 × 106 to 12.78 × 106 g−1 soil, respectively. Furthermore, both of them were lower in meadow soil than shrub soil. Statistical analysis revealed that diversity and copies of nifH gene mostly correlated with aboveground biomass in shrub soil. In meadow soil, nifH gene diversity was principally affected by altitude while copies did by soil available K.
F. M. M. Morel - One of the best experts on this subject based on the ideXlab platform.
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Multiple roles of siderophores in free-living Nitrogen-Fixing Bacteria
BioMetals, 2009Co-Authors: Anne M. L. Kraepiel, J. P. Bellenger, T. Wichard, F. M. M. MorelAbstract:Free-living Nitrogen-Fixing Bacteria in soils need to tightly regulate their uptake of metals in order to acquire essential metals (such as the Nitrogenase metal cofactors Fe, Mo and V) while excluding toxic ones (such as W). They need to do this in a soil environment where metal speciation, and thus metal bioavailability, is dependent on a variety of factors such as organic matter content, mineralogical composition, and pH. Azotobacter vinelandii, a ubiquitous gram-negative soil diazotroph, excretes in its external medium catechol compounds, previously identified as siderophores, that bind a variety of metals in addition to iron. At low concentrations, complexes of essential metals (Fe, Mo, V) with siderophores are taken up by the Bacteria through specialized transport systems. The specificity and regulation of these transport systems are such that siderophore binding of excess Mo, V or W effectively detoxifies these metals at high concentrations. In the topsoil (leaf litter layer), where metals are primarily bound to plant-derived organic matter, siderophores extract essential metals from natural ligands and deliver them to the Bacteria. This process appears to be a key component of a mutualistic relationship between trees and soil diazotrophs, where tree-produced leaf litter provides a living environment rich in organic matter and micronutrients for Nitrogen-Fixing Bacteria, which in turn supply new Nitrogen to the ecosystem.
X. K. Wu - One of the best experts on this subject based on the ideXlab platform.
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high diversity of Nitrogen Fixing Bacteria in the upper reaches of the heihe river northwestern china
Biogeosciences, 2013Co-Authors: T. Chen, W. Zhang, X. K. Wu, Haozhi Long, Binglin Zhang, Yuqing ZhangAbstract:Vegetation plays a key role in water conservation in the southern Qilian Mountains (northwestern China), located in the upper reaches of the Heihe River. Nitrogen-Fixing Bacteria are crucial for the protection of the Nitrogen supply for vegetation in the region. In the present study, nifH gene clone libraries were established to determine differences between the Nitrogen-Fixing Bacterial communities of the Potentilla parvifolia shrubland and the Carex alrofusca meadow in the southern Qilian Mountains. All of the identified Nitrogen-Fixing Bacterial clones belonged to the ProteoBacteria. At the genus level, Azospirillum was only detected in the shrubland soil, while Thiocapsa , Derxia , Ectothiorhodospira , Mesorhizobium , Klebsiella , Ensifer , Methylocella and Pseudomonas were only detected in the meadow soil. The phylogenetic tree was divided into five lineages: lineages I, II and III mainly contained nifH sequences obtained from the meadow soils, while lineage IV was mainly composed of nifH sequences obtained from the shrubland soils. The Shannon–Wiener index of the nifH genes ranged from 1.5 to 2.8 and was higher in the meadow soils than in the shrubland soils. Based on these analyses of diversity and phylogeny, the plant species were hypothesised to influence N cycling by enhancing the fitness of certain Nitrogen-Fixing taxa. The number of nifH gene copies and colony-forming units (CFUs) of the cultured Nitrogen-Fixing Bacteria were lower in the meadow soils than in the shrubland soils, ranging from 0.4 × 10 7 to 6.9 × 10 7 copies g −1 soil and 0.97 × 10 6 to 12.78 × 10 6 g −1 soil, respectively. Redundancy analysis (RDA) revealed that the diversity and number of the nifH gene copies were primarily correlated with aboveground biomass in the shrubland soil. In the meadow soil, nifH gene diversity was most affected by altitude, while copy number was most impacted by soil-available K. These results suggest that the Nitrogen-Fixing Bacterial communities beneath Potentilla were different from those beneath Carex .
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High diversity of Nitrogen-Fixing Bacteria in upper reaches of Heihe River, Northwestern China
Biogeosciences Discussions, 2013Co-Authors: T. Chen, W. Zhang, X. K. Wu, H. Z. Long, B. G. ZhangAbstract:Abstract. Vegetation plays a key role to water conservation in southern Qilian Mountains (Northwestern China), the upper reaches of Heihe River. Nitrogen-Fixing Bacteria are crucial for vegetation protection because they can supply plants with Nitrogen source. Nevertheless, little is known about Nitrogen-Fixing Bacteria in this region. In present study, nifH gene clone libraries were established for detecting the difference of Nitrogen-Fixing Bacterial communities between Potentilla parvifolia shrub and Carex alrofusca meadow in the southern Qilian Mountains. All the identified Nitrogen-Fixing Bacterial clones belonged to ProteoBacteria. At the genus level, the Azospirillum sp. was only detected in shrub soil while Thiocapsa sp., Derxiasp., Ectothiorhodospira sp., Mesorhizobium sp., Klebsiella sp., Ensifer sp., Methylocella sp. and Peseudomonas sp. were just detected in meadow soil. Shannon–Wiener index of nifH gene ranged from 1.5 to 2.8 and was higher in meadow soil than shrub soil. Contrarily, the nifH gene copies and CFUs of cultured Nitrogen-Fixing Bacteria ranged from 0.4 × 107 to 6.9 × 107 copies g−1 soil and 0.97 × 106 to 12.78 × 106 g−1 soil, respectively. Furthermore, both of them were lower in meadow soil than shrub soil. Statistical analysis revealed that diversity and copies of nifH gene mostly correlated with aboveground biomass in shrub soil. In meadow soil, nifH gene diversity was principally affected by altitude while copies did by soil available K.