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Nitrogen Fixation by symbiotic organisms is considered an important contribution to the solution of food problems throughout the world. For manyyears, Chinese scientists have focused their research in this area. Today more than half of the total nitrogen fertilizers applied are from biological fixation sources. The editor is an international renowned scientist at the Chinese Academy of sciences. He has brought together contributions from various research fields in China and Europe.Together they present the state-of-the-art in nitrogen-fixation research. The studies range from actino- mycete fixation induced in various genera andspecies of plants, mechanisms and chemical modeling of enzyme systems togenetical engineering of organisms.

Biological nitrogen fixation provides more than 50% of the total annual input of the essential element nitrogen to world agriculture. Thus, it is of immense agronomic importance and critical to food supplies, particularly in developing countries. This book, with chapters authored by internationally renowned experts, provides a comprehensive and detailed account of the fascinating history of the process - including the surprising discoveries of molybdenum-independent nitrogenases and superoxide-dependent nitrogenase; a review of Man's attempts to emulate the biological process - most successfully with the commercially dominant Haber-Bosch process; and the current state of the understanding art with respect to the enzymes - called nitrogenases - responsible for biological nitrogen fixation. The initial chapters use a historical approach to the biological and industrial processes, followed by an overview of assay methodologies. The next set of chapters focuses on the classical enzyme, the molybdenum nitrogenase, and details its biosynthesis, structure, composition, and mechanism of action as well as detailing both how variants of its two component proteins are constructed by recombinant DNA technology and how computational techniques are being applied. The sophisticated chemical modelling of the metal-containing clusters in the enzyme is reviewed next, followed by a description of the two molybdenum-independent nitrogenases - first, the vanadium-containing enzyme and then the iron-only nitrogenase - together with some thoughts as to why they exist! Then follows an up-to-date treatment of the clearly'non-classical'properties of the superoxide-dependent nitrogenase, which more closely resembles molybdenum-containing hydroxylases and related enzymes, like nitrate reductase, that it does the other nitrogenases. Each chapter contains an extensive list of references. This book is the self-contained first volume of a comprehensive seven-volumeseries. No other available work provides the up-to-date and in-depth coverage of this series and this volume. This book is intended to serve as an indispensable reference work for all scientists working in this area, including agriculture and the closely related metals-in-biology area; to assist students to enter this challenging area of research; and to provide science administrators easy access to vital relevant information.

Our knowledge of the biochemistry and biophysics of dinitrogen fixa­ tion has developed rapidly in the 15 years since the first N2-fixing enzyme system was successfully extracted from a bacterium. This peri­ od has produced a literature that now describes the N2 fixation reac­ tion and the nitrogenase enzyme itself in sophisticated terms, though a detailed reaction mechanism at the chemical level has not yet emerged. It is the purpose of the present monograph to present an in-depth re­ view, analysis, and integration of this research as is possible with a non-contributed publication and to relate this work to considera­ tions of N2 fixation that reach beyond the confines of the biochem­ ist's laboratory. The first section is directed as much toward the general science read­ er as toward the specialist. It covers the agricultural origins of man's interest in N2 fixation and also pertinent areas of taxonomy, physiology, and evolution. Ecological aspects of the subject include a comprehensive evaluation of the nitrogen cycle leading to a sub­ stantially greater estimate of the rate of global N2 fixation than previous ones. The treatment is of a survey fashion, in part to pro­ vide a general over-view of N2 fixation and in part to provide context for the biochemistry and biophysics that follow in the second section.

Understanding of biological nitrogen fixation has advanced with impressive rapidity during the last decade. As befits a developing area of Science, these advances have uncovered information and raised questions which will have, and indeed have had, repercussions in numerous other branches of science and its applications. This'information explosion', to use one of to-day's cant idioms, was initiated by the discovery, by a group of scientists working in the Central Research laboratories of Dupont de Nemours, U. S. A., of a reproducibly active, cell-free enzyme preparation from a nitrogen­ fixing bacterium. Full credit is due to them. But subsequent developments, albeit sometimes quite as impressive, have too often been marked by that familiar disorder of a developing field of research-the scramble to publish. It is a scramble which, at its best, may represent a laudable desire to inform colleagues of the latest developments; yet which too easily develops into an undignified rush for priority, wherewith to impress one's Board of Directors or Grant-giving Institution. This, in miniature, is the tragedy of scientific research to-day: desire for credit causes research to be published in little bulletins, notes and preliminary communications, so that only those intimately involved in the field really know what is happening (and even they may well not see the forest for the trees). Those outside the field, or working in peripheral areas, may glean something of what is going on from reviews and fragments presented at meetings, but the broad pattern of development is often elusive.

A full review of the latest research findings on microbes involved in conventional aerobic nitrification, anaerobic ammonia oxidation, and related processes.

Nodules produced on legume roots by root-nodule bacteria provide the major nitrogenous input into natural and agricultural systems worldwide. This book provides an in-depth and up-to-the minute analysis of what is known about this symbiosis, its origins, the process of nodule formation and development, and the biochemistry and genetics of nodular nitrogen fixation. It also reviews the physiology of the root-nodule bacteria themselves, their ecology in both natural and agricultural systems, and how we go about introducing new legumes and the bactria they require. How all the knowledge gained about this system can be applied in the future for better legume-rhizobia functioning in difficult environments is its logical culmination.

Associative and Endophytic Nitrogen-fixing Bacteria and Cyanobacterial Associations This book is part of the seven-volume series that was launched a few years ago with the ambitious objectives of reviewing the field of nitrogen fixation from its earliest beginnings through the millennium change and of consolidating the relevant information - from fundamental to agricultural and environmental aspects – all in one place. Volume 5 covers the biology of bacteria that associate with n- leguminous plants. The subject matter includes a wide range of associations; it covers the bacterial species that associate either with the surface or within the tissues of grasses (often referred as plant growth-promoting rhizobacteria) and also the symbiotic associations that cyanobacteria form with fungi, algae, and both lower and higher plants. This volume does not deal with the Frankia-actinorhizal plant associations, which is the topic of Volume 6. The book is divided in 13 chapters, each of which is the work of well-known scientists in the field. Just like in the other volumes of this series, the first chapter is th an historical perspective. It describes how, as early as the end of the 19 century, it was shown that plant exudation favoured the proliferation of soil bacteria in the rhizosphere, and how the first nitrogen-fixing bacteria, including cyanobacteria were isolated. The chapter covers the landmarks and scientific concepts that arose from more than one century of research in this area.

Genomes and Genomics of Nitrogen-fixing Organisms This is Volume 3 of a seven-volume series on all aspects of Nitrogen Fixation. The series aims to be the definitive authority in the field and to act as a benchmark for some years to come. Rather than attempting to cram the whole field into a single volume, the subject matter is divided among seven volumes to allow authors the luxury of writing in depth with a comprehensive reference base. All authors are recognized practicing scientists in the area of their contribution, which ensures the high quality, relevance, and readability of the chapters. In establishing the rationale for, and the organization of, this book, we realized the need to divide it into two sections. The first section should be organism based and should review our current knowledge of the genomes of nitrogen-fixing organisms and what these nucleotide sequences tell us. The second section should then be technology based. It should review what technologies are available to mine the data inherent in the nucleotide sequences and how they are now being used to produce gene-function data from differential gene expression.

Sustainability has a major part to play in the global challenge of continued development of regions, countries, and continents all around the World and biological nitrogen fixation has a key role in this process. This volume begins with chapters specifically addressing crops of major global importance, such as soybeans, rice, and sugar cane. It continues with a second important focus, agroforestry, and describes the use and promise of both legume trees with their rhizobial symbionts and other nitrogen-fixing trees with their actinorhizal colonization. An over-arching theme of all chapters is the interaction of the plants and trees with microbes and this theme allows other aspects of soil microbiology, such as interactions with arbuscular mycorrhizal fungi and the impact of soil-stress factors on biological nitrogen fixation, to be addressed. Furthermore, a link to basic science occurs through the inclusion of chapters describing the biogeochemically important nitrogen cycle and its key relationships among nitrogen fixation, nitrification, and denitrification. The volume then provides an up-to-date view of the production of microbial inocula, especially those for legume crops.

The turn of the millennium from the twentieth to the twenty-first century provides an occasion to review our understanding of a biological process, biological nitrogen fixation, that is of prime importance for the continued survival of mankind. This process has provided a basis for maintaining soil fertility since the beginning of organised agriculture, yet its very existence was confirmed only just over a century ago. In the intervening years, an enormous intellectual effort has dispersed much of the mystery surrounding biological nitrogen fixation. Biological fixation is widely exploited in agriculture, as are nitrogen fertilisers prepared for the last hundred years under extreme conditions of temperature and pressure. However, despite all our efforts, the fundamental nature of the reactions involved at the heart of the biological process remain unknown. This book aims to describe what we have learned in the last one hundred years or so about biological nitrogen fixation, about what its chemistry appears to be, and how it is applied in agriculture. This ambitious objective has not been attempted recently. It is aimed at students and those who wish to enter these very challenging areas of research, and who need to learn the state of the art at the turn of the millennium.The authors are all acknowledged world experts in their fields. They have prepared concise, well referenced and authoritative accounts of their subjects. This book provides a unique summary of the current state of knowledge that will be indispensable to all students and researchers, actual and potential, interested in biological nitrogen fixation.

Committee chair: Ralph W.F. Hardy.