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Nitrogen fixation. Vol. 2, Rhizobium
88 NITROGEN FIXATION
Nitrogen fixation. Vol. 2, Rhizobium. W.J. Broughton (Editor). Oxford University Press, Oxford, 1982, 353 pp., £25.00, ISBN 0-19-854552-5. This volume is the second of a series of four; the first covering Ecology, the third Legumes and the fourth the Molecular Biology of Nitrogen Fixation. This reverses the usual subject order in which the basic chemical and biochemical aspects are thought to be more fundamental and therefore qualify for early exposition. These volumes also differ importantly from other symposia in having fewer contributors, each dealing more fully and broadly with their sector than would be appropriate in a more specialized article. An authoritative text of this kind may fulfil a need, but has its problems in so rapidly developing a subject, the chief of which is editorial: to assemble a well-balanced team of authors able to cover the whole field in an up-to
89 under stress. The literature list is extensive and useful but omits important recent papers and symposia such as 'Microbial Ecology' edited by M.W. Loutit and J.A.R. Miles, Springer Verlag, 1978. Chapter 3, the longest contribution with the all-embracing title 'Biology' examines exhaustively the characteristics of Rhizobium: morphology, nutrition, metabolism, phage suceptibility, serology, etc., and discusses thoroughly the taxonomy and evolution of the Rhizobium--Legume symbiosis, partly dealt with elsewhere. The metabolism of carbohydrates by Rhizobium is the central theme of chapter 4. It refers to the demands made for energy in the nitrogen fixing process and the use that can be made of carbohydrate metabolism in classification. This is followed by a brief, but up-to-date review of the genetics of Rhizobium, describing the use of mutants and methods of gene transfer, the importance of plasmids as carriers of nitrogen-fixing genes and the use of genetics in understanding root nodule biochemistry and energy relationships. Although not yet worked out for Rhizobium, some mention should have been made of the epoch making work on the genetics of nitrogenase in Klebsiella, especially as complementation studies have shown strong affinities between Rhizobium and the free living nitrogen fixers. If this important matter is to be covered in a later volume, this should be indicated. Chapter 6 is a clear and well-illustrated exposition of the fine structure of the cultured Rhizobium cell, contrasting the slow and fast growing strains, and bringing together results from the techniques of thin sectioning, freeze fracturing and etching and immuno-electron microscopy. This detailed description links well with the following article on the surface chemistry of rhizobia. It points out that although much is now known about the detailed chemistry of the extracellular polysaccharides (ECPS) and lipopolysaccharides (LPS) of Rhizobium, there is as yet no aspect of attachment, infection or specificity that can be related unambiguously to structure. Interesting indications connecting ECPS and LPS with the attachment of Rhizobium to the root surface or to infection may have to await explanation from a better understanding of the subtle differences in structural chemistry. The not unconnected subject of serology is comprehensively reviewed in chapter 8. This describes the nature and range of rhizobial antigens and the methods available for their study. The final section of the article deals with the use of serology in elucidating problems of taxonomy, ecology and nodule biochemistry. In discussing the control of root hair infection {chapter 9), the adsorption, recognition (two stages} and cell penetration phases are distinguished. This is followed by a balanced and full presentation of the lectin hypothesis, to which the authors have largely contributed, and concludes with the view that the hypothesis awaits conclusive proof. Their interpretation of the mechanism of thread initiation rests heavily upon as yet unpublished Ph.D. Thesis work from which plates (unfortunately without identifying symbols) are taken. Remarkably, in spite of its length the chapter avoids mentioning IAA.
90
The final chapter on nodule structure and growth also has a small section on infection processes. It distinguishes the different modes of development of apical and spherical nodules. Attention is given to some of the biochemical aspects relative to structure and to ineffective associations. The subject matter is very extensive and could have benefited from more thorough treatment. The volume is very well produced with clear text, figures, tables and plates, and with very few typographical lapses (sadly with one in the second sentence of the Preface). Its defects, c o m m o n to works of this kind, stem from the failure of the editor to discipline his team sufficiently to provide a well balanced and up-to-date conspectus of the subject and to avoid needless repetition.
P.S. NUTMAN
Great Hackworthy Cottage Tedburn St. Mary Exeter EX6 6DW, Gt. Britain
A G R I C U L T U R A L MICROBIOLOGY
Advances in Agricultural Microbiology. N.S. Subba-Rao (Editor). Butterworths, Kent, 1982, xxii + 704 pp., £35.00 (hb), ISBN 0-408-10848-7. This is a book full of pleasant surprises. The reader could immediately be disappointed with the prospect that recent developments in agricultural microbiology, outside of soil science, will be ignored, because the foreword starts "Though agricultural microbiology is a relatively new branch of soil science ..... ". However, even a quick scan of the contents list shows the vast range of topics to be covered, including some not traditionally associated with the study of soils. The next surprise on the contents list is that Dr. Subba-Rao has marshalled together so many international experts to contribute to a single volume. Following an overview of agricultural microbiology by S.H. Wittwer as an introductory chapter, there follow three sections. In the first on micro-organisms and mobilization of nutrients for plant growth, there are thirteen chapters: Microbial genetics and biological nitrogen fixation (J.E. Beringer); Physiology and biochemistry of biological nitrogen fixation in legumes (C.A. Atkins and R.M. Rainbird); Ureide metabolism and the significance of ureides in legumes (C.A. Atkins); Nitrogen fixation in nodulated plants other than legumes (J.H. Becking); Plant surface microflora and plant nutrition (K. G. Mukerji and N.S. Subba-Rao); New developments in grass--bacteria asso-
Nitrogen fixation. Vol. 2, Rhizobium. W.J. Broughton (Editor). Oxford University Press, Oxford, 1982, 353 pp., £25.00, ISBN 0-19-854552-5. This volume is the second of a series of four; the first covering Ecology, the third Legumes and the fourth the Molecular Biology of Nitrogen Fixation. This reverses the usual subject order in which the basic chemical and biochemical aspects are thought to be more fundamental and therefore qualify for early exposition. These volumes also differ importantly from other symposia in having fewer contributors, each dealing more fully and broadly with their sector than would be appropriate in a more specialized article. An authoritative text of this kind may fulfil a need, but has its problems in so rapidly developing a subject, the chief of which is editorial: to assemble a well-balanced team of authors able to cover the whole field in an up-to
89 under stress. The literature list is extensive and useful but omits important recent papers and symposia such as 'Microbial Ecology' edited by M.W. Loutit and J.A.R. Miles, Springer Verlag, 1978. Chapter 3, the longest contribution with the all-embracing title 'Biology' examines exhaustively the characteristics of Rhizobium: morphology, nutrition, metabolism, phage suceptibility, serology, etc., and discusses thoroughly the taxonomy and evolution of the Rhizobium--Legume symbiosis, partly dealt with elsewhere. The metabolism of carbohydrates by Rhizobium is the central theme of chapter 4. It refers to the demands made for energy in the nitrogen fixing process and the use that can be made of carbohydrate metabolism in classification. This is followed by a brief, but up-to-date review of the genetics of Rhizobium, describing the use of mutants and methods of gene transfer, the importance of plasmids as carriers of nitrogen-fixing genes and the use of genetics in understanding root nodule biochemistry and energy relationships. Although not yet worked out for Rhizobium, some mention should have been made of the epoch making work on the genetics of nitrogenase in Klebsiella, especially as complementation studies have shown strong affinities between Rhizobium and the free living nitrogen fixers. If this important matter is to be covered in a later volume, this should be indicated. Chapter 6 is a clear and well-illustrated exposition of the fine structure of the cultured Rhizobium cell, contrasting the slow and fast growing strains, and bringing together results from the techniques of thin sectioning, freeze fracturing and etching and immuno-electron microscopy. This detailed description links well with the following article on the surface chemistry of rhizobia. It points out that although much is now known about the detailed chemistry of the extracellular polysaccharides (ECPS) and lipopolysaccharides (LPS) of Rhizobium, there is as yet no aspect of attachment, infection or specificity that can be related unambiguously to structure. Interesting indications connecting ECPS and LPS with the attachment of Rhizobium to the root surface or to infection may have to await explanation from a better understanding of the subtle differences in structural chemistry. The not unconnected subject of serology is comprehensively reviewed in chapter 8. This describes the nature and range of rhizobial antigens and the methods available for their study. The final section of the article deals with the use of serology in elucidating problems of taxonomy, ecology and nodule biochemistry. In discussing the control of root hair infection {chapter 9), the adsorption, recognition (two stages} and cell penetration phases are distinguished. This is followed by a balanced and full presentation of the lectin hypothesis, to which the authors have largely contributed, and concludes with the view that the hypothesis awaits conclusive proof. Their interpretation of the mechanism of thread initiation rests heavily upon as yet unpublished Ph.D. Thesis work from which plates (unfortunately without identifying symbols) are taken. Remarkably, in spite of its length the chapter avoids mentioning IAA.
90
The final chapter on nodule structure and growth also has a small section on infection processes. It distinguishes the different modes of development of apical and spherical nodules. Attention is given to some of the biochemical aspects relative to structure and to ineffective associations. The subject matter is very extensive and could have benefited from more thorough treatment. The volume is very well produced with clear text, figures, tables and plates, and with very few typographical lapses (sadly with one in the second sentence of the Preface). Its defects, c o m m o n to works of this kind, stem from the failure of the editor to discipline his team sufficiently to provide a well balanced and up-to-date conspectus of the subject and to avoid needless repetition.
P.S. NUTMAN
Great Hackworthy Cottage Tedburn St. Mary Exeter EX6 6DW, Gt. Britain
A G R I C U L T U R A L MICROBIOLOGY
Advances in Agricultural Microbiology. N.S. Subba-Rao (Editor). Butterworths, Kent, 1982, xxii + 704 pp., £35.00 (hb), ISBN 0-408-10848-7. This is a book full of pleasant surprises. The reader could immediately be disappointed with the prospect that recent developments in agricultural microbiology, outside of soil science, will be ignored, because the foreword starts "Though agricultural microbiology is a relatively new branch of soil science ..... ". However, even a quick scan of the contents list shows the vast range of topics to be covered, including some not traditionally associated with the study of soils. The next surprise on the contents list is that Dr. Subba-Rao has marshalled together so many international experts to contribute to a single volume. Following an overview of agricultural microbiology by S.H. Wittwer as an introductory chapter, there follow three sections. In the first on micro-organisms and mobilization of nutrients for plant growth, there are thirteen chapters: Microbial genetics and biological nitrogen fixation (J.E. Beringer); Physiology and biochemistry of biological nitrogen fixation in legumes (C.A. Atkins and R.M. Rainbird); Ureide metabolism and the significance of ureides in legumes (C.A. Atkins); Nitrogen fixation in nodulated plants other than legumes (J.H. Becking); Plant surface microflora and plant nutrition (K. G. Mukerji and N.S. Subba-Rao); New developments in grass--bacteria asso-