Nitrogen fixation

About: Nitrogen fixation is a research topic. Over the lifetime, 7940 publications have been published within this topic receiving 232921 citations. The topic is also known as: GO:0009399.

Enhancement of symbiotic dinitrogen fixation by a toxin-releasing plant pathogen.

Abstract: An approximate doubling in plant growth, total plant nitrogen, nodulation, and overall dinitrogen fixation of alfalfa are the consequences of the action of a toxin delivered by a Pseudomonas infesting the alfalfa rhizosphere. The toxin, tabtoxinine-beta-lactam, inactivates selectively one form of glutamine synthetase in the nodules. Thus, normal glutamine synthetase-catalyzed ammonia assimilation is significantly impaired; yet these plants assimilated about twice the normal amount of nitrogen. How plants regulate dinitrogen fixing symbiotic associations is an important and unresolved question; the current results imply that the glutamine synthetase-catalyzed step in ammonia assimilation, a plant function, strongly influences overall dinitrogen fixation in legumes.

Genetics and regulation of nitrogen fixation in free-living bacteria

Abstract: Series Preface Preface List of Contributors Dedication 1: Historical Perspective - Development of nif Genetics and Regulation in Klebsiella pneumoniae R Dixon 1 Introduction 2 The Early Years 3 Defining the K pneumoniae nif Genes 4 The Recombinant DNA Era 5 nif Gene Regulation 6 Coda References 2: Genetics of Nitrogen Fixation and Related Aspects of Metabolism in Species of Azotobacter: History and Current Status C Kennedy and P Bishop 1 Research on the Genus Azotobacter (1901-2003) 2 Application of the Tools of Genetics and Molecular Biology in Species of Azotobacter 3 The nif Genes encoding the Enzymes for Structure, Function, and Biosynthesis of Mo-containing Nitrogenase 4 Regulation of Expression of nif and Associated Genes by Ammonium and O2 5 Ancillary Properties of Azotobacter Species that Aid the Efficiency of Nitrogen Fixation 6 Discovery of Molybdenum-independent Nitrogenase Systems in A vinelandii 7 Molybdenum-independent Nitrogenase systems in other Azotobacter Species Acknowledgements References 3: Nitrogen Fixation in the Clostridia J-S Chen 1 Introduction 2 The Nitrogen-fixing Clostridia 3 Distinctive Features of the nif Genes of the Clostridia 4 Genes of Ammonia Assimilation 5 Regulation of Nitrogen Fixation and Ammonia Assimilation 6 Concluding Remarks References 4: Regulation of Nitrogen Fixation in Methanogenic Archaea JA Leigh 1 Introduction 2 History and Background 3 Transcriptional Regulation 4 Regulation of Nitrogenase Activity 5 Summary References 5: Nitrogen Fixation in Heterocyst-Forming Cyanobacteria T Thiel 1Introduction 2 Structure of Heterocysts 3 Nitrogenase Genes 4 Heterocyst Metabolism 5 Genes Important for Heterocyst Formation 6 heterocyst Pattern Formation 7 Regulation Acknowledgements References 6: N2 Fixation by Non-Heterocystous Cyanobacteria JR Gallon 1 Introduction 2 Non-heterocystous Cyanobacteria 3 Patterns of N2 Fixation Acknowledgements References 7: Nitrogen Fixation in the Photosynthetic Purple Bacterium Rhodobacter capsulatus B Masepohl, T Drepper and W Klipp 1 Introduction 2 Organization of Nitrogen-fixing Genes 3 The Nitrogen-fixation Regulon of R capsulatus 4 Ammonium Control of Synthesis and Activity of both Nitrogenases 5 Environmental Factors Controlling Nitrogen Fixation 6 Linkage of Nitrogen Fixation, Photosynthesis, and Carbon Dioxide Assimilation 7 Nitrogen Fixation in other Photosynthetic Purple Bacteria References 8: Post-translational Regulation of Nitorgenase in Photosynthetic Bacteria S Nordlund and PW Ludden 1 Introduction 2 Discovery of Nitrogen Fixation by Photosynthetic Bacteria 3 In vitro Studies of Nitrogenase in Photosynthetic Bacteria 4 The Protein Era 5 Evidence for the Drat/Drag System in other Organisms 6 Other ADP-Ribosylations 7 Genetics of the Drag/Drat System 8 Signal Transduction to Drat and Drat 9 Conclustions Acknowledgement References 9: Regulation of Nitrogen Fixation in Free-Living Diazotrophs MJ Merrick 1 Introduction 2 General Nitrogen Control Systems 3 nif-specific Nitrogen Control 4 Nitrogen Control of Nitrogenase Activity 5 Conclusions References 10: Molybdenum Uptake and Homeostatis RN Pau 1 Molybdenum Outside Cells 2

Improvement of Symbiotic Properties in Rhizobium leguminosarum by Plasmid Transfer

Abstract: SUMMARY: Transfer of plasmid pIJ1008, a recombinant of two indigenous Rhizobium leguminosarum plasmids into R. leguminosarum strain 300 produced strain 3960, which reduced significantly more N2 in pea root nodules than did strain 300 itself. Strain 3960 was superior to the field isolate 128C53, from which the symbiotic determinants of pIJ1008 were derived, and transfer of plasmid pIJ1008 into two other genetic backgrounds also improved symbiotic performance compared to the introduction of other nodulation plasmids. As plasmid pIJ1008 carries genetic determinants for an uptake hydrogenase activity (Hup+) as well as nodulation capability (Nod+) and other determinants for symbiotic nitrogen fixation (Fix+), the increased effectiveness of strains carrying pIJ1008 may result from their capacity to conserve energy by recovering H2 evolved by nitrogenase. Intact plant studies with 15N showed that the superior N2 fixation capability associated with pIJ1008 was enhanced by 2 mm-NO3 -, a common concentration of soil N. It was also shown that, as plants grew older, the hydrogenase determined by pIJ1008 was not able to recycle all the hydrogen evolved by pea root nodules.

Nitrogen-fixing symbiosis between photosynthetic bacteria and legumes

Abstract: Rhizobia having photosynthetic systems form nitrogen-fixing nodules on the stem and/or root of some species of the legumes Aeschynomene and Lotononis. This review is focused on the recent knowledge about the physiology, genetics and role of the photosystem in these bacteria. Photosynthetic electron transport seems to involve reaction centers, soluble cytochrome c2 and cytochrome bc1. Anaerobically, the electron transport system becomes over-reduced. The photosynthesis genes have been partially characterized; their organization is classical but their regulation is unusual as it is activated by far-red light via a bacteriophytochrome. This original mechanism of regulation seems well adapted to promote photosynthesis during stem symbiosis. Photosynthesis plays a major role in the efficiency of stem nodulation. It is also observed that infrared light stimulates nitrogen fixation in nodules containing photosynthetic bacteroids, suggesting that photosynthesis may additionally provides energy for nitrogen fixation, allowing for more efficient plant growth. Other aspects of these bacteria are discussed, in particular their taxonomic position and nodulation ability, the role of carotenoids and the potential for application of photosynthetic rhizobia in rice culture.

Enzymology and ecology of the nitrogen cycle.

Abstract: The nitrogen cycle describes the processes through which nitrogen is converted between its various chemical forms. These transformations involve both biological and abiotic redox processes. The principal processes involved in the nitrogen cycle are nitrogen fixation, nitrification, nitrate assimilation, respiratory reduction of nitrate to ammonia, anaerobic ammonia oxidation (anammox) and denitrification. All of these are carried out by micro-organisms, including bacteria, archaea and some specialized fungi. In the present article, we provide a brief introduction to both the biochemical and ecological aspects of these processes and consider how human activity over the last 100 years has changed the historic balance of the global nitrogen cycle.