Microbes and Man Microbes are everywhere. Normally invisible, they are abundant in the air we breathe, in soil, in water, on our skin and hair, in our mouths and intestines, on and in the food we eat. They make the soil fertile; they clean up the environment; they change, often improve, our food; some protect us from less desirable microbes. Yet most people are scarcely aware that they exist – except when they become ill. Microbes, as ‘germs’, are widely regarded as nasty, unpopular because a few can cause disease and a few can spoil food. Yet collectively microbes present a fascinating world of minuscule creatures, who together encompass all the processes of which terrestrial life is capable: creatures who have profound e¤ects on our lives and surroundings. In this up-dated edition, the extraordinary impact which the microbial community has on our everyday lives is described in an accessible and easy to read style. John Postgate frs is Emeritus Professor of Microbiology at the University of Sussex and former Director of the AFRC Unit of Nitrogen Fixation. He was educated at Kingsbury County and other schools, and at Balliol College, Oxford, where he took a first degree in chemistry before turning to chemical microbiology. He then spent fifteen years in government research establishments – studying mainly the sulphur bacteria and bacterial death – before moving to the Unit at Sussex, where he spent the next twenty-two years. He has held visiting professorships at the University of Illinois and Oregon State University and has been President of the Institute of Biology and of the Society for General Microbiology. He is also the author of The Sulphate-Reducing Bacteria, Nitrogen Fixation and The Outer Reaches of Life. He is the third Professor John Postgate: the first (his great-grandfather) taught medicine at Birmingham University, the second (his grandfather) taught classics at Cambridge and Liverpool Universities. His other grand- father was George Lansbury, the Socialist leader, and his father was Raymond Postgate, the historian and gourmet. Long ago John Postgate led the Oxford University Dixieland Bandits (on cornet) and he is known as a jazz writer. He and his wife, Mary, who read English at St Hilda’s College, have three grown-up daughters and seven grandchildren. Fourth Edition University of Sussex John Postgate Microbes and Man published by the press syndicate of the university of cambridge The Pitt Building, Trumpington Street, Cambridge, United Kingdom cambridge university press The Edinburgh Building, Cambridge CB2 2RU, UK 40 West 20th Street, New York, NY 10011–4211, USA 477 Williamstown Road, Port Melbourne, VIC 3207, Australia Ruiz de Alarcón 13, 28014 Madrid, Spain Dock House, The Waterfront, Cape Town 8001, South Africa http://www.cambridge.org © Cambridge University Press 2000 This book is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published by Penguin Books Ltd 1969 Reprinted with revisions and plates 1975 Reprinted 1976, 1979 Second edition 1986 Third edition published by the Cambridge University Press 1992 Reprinted 1992, 1996, 1997 Fourth edition 2000 Reprinted 2001, 2003 TypefaceFFScala10.5/15pt.SystemQuarkXPress®[se] A catalogue record for this book is available from the British Library Library of Congress Cataloguing in Publication data Postgate, J. R. (John Raymond) Microbes and man / John Postgate. – 4th ed. p. cm. Includes bibliographical references and index. ISBN 0 521 66579 5 1. Microbiology–Popular works. I. Title. QR56.P58.1999 579–dc21 99–13564 CIP ISBN 0 521 66579 5 paperback Transferred to digital printing 2004 To the memory of H.J.Bunker and K.R.Butlin Contents Illustrations ix Preface xi 1 Man and microbes 1 2 Microbiology 17 3 Microbes in society 54 4 Interlude: how to handle microbes 113 5 Microbes in nutrition 133 6 Microbes in production 171 7 Deterioration, decay and pollution 243 8 Disposal and cleaning-up 270 9 Second interlude: microbiologists and man 291 10 Microbes in evolution 308 11 Microbes in the future 335 Further reading 358 Glossary 360 Index 363 Illustrations A microscopic green alga 21 A protozoon 22 A filamentous microfungus 23 A virus 25 Some bacteria 29 Microbes grow in a hot spring 37 Life in the Galapagos Rift 41 Some sulphate-reducing bacteria 47 Electron micrograph of Neisseria meningitidis 59 A seal has died of phocine distemper 74 The hand of Sarah Nelmes 82 Bacteria on the surface of a tooth 99 The drastic e¤ect of Dutch elm disease 102 Colonies of bacteria in a laboratory 117 A hoatzin or stinky cowbird 135 A case of BSE 140 Root nodules containing nitrogen-fixing bacteria 148 A market for green manure 151 Unseen friends in yoghurt 158 A sulphur-forming lake in Libya 177 A red, photosynthetic sulphur bacterium 178 An industrial fermenter 198 A plasmid 216 Diagram of a plasmid 218 DNR fingerprints resolve a question of paternity 232 A triumph of genetic engineering 237 Bacteria corrode iron pipes 259 x list of illustrations Fish are killed by bacterial sulphate reduction 263 Genetic engineering – Shock! Horror! 294 Fossil microbes in ancient rock 318 A microbe’s eye view of its family tree 331 Nanedi Vallis on Mars 350 Preface to the fourth edition Nearly thirty years ago I wrote the first edition of Microbes and Man.It was an attempt to introduce educated readers, not necessarily scien- tists, to the world of microbes, and to survey the impact of these crea- tures on Mankind’s economy and society. The book was a quiet success, I am happy to say: it has been translated into several lan- guages and, because the study of microbes continues to advance in fascinating directions, this is its third major revision. Microbes have a truly enormous influence on people’s lives. They clean up the environment and they make soil fertile; they are all- important in food technology; they make vitamins within our bodies. They can live peacefully within, around and upon us, and some even protect us from other, harmful, microbes, Yet most people are hardly aware that they exist – until a microbial misfortune happens: perhaps a disease breaks out, some food is spoiled, or some valuable or treasured material is found to have rotted or otherwise deteri- orated. Only then do most people remember microbes – so it is hardly surprising that they are widely regarded as nasty; invisible enemies that are to be feared or resented. In my book I wished to change the microbe’s unfortunate public image. Of course, it is true that some microbes, especially certain bacteria and viruses, cause illnesses; of course, too, microbes exist which spoil food and attack non-living material – even damaging such improbable objects as concrete and iron pipes. But most microbes are beneficial. Their value to the food, chemical and phar- maceutical industries is (I hope) well-known to students, and perhaps, since the flowering of genetic engineering, to a minority of laymen. But few non-specialists are aware of the crucially important part microbes play, for example, in sewage treatment and waste xii preface to the fourth edition disposal. After all, who outside a sewage works wishes to know about sewage? Yetsewage treatment is absolutely fundamental to our social well-being. And microbes have e¤ects of global importance, as when they clean up fouled lakes, rivers and beaches, or decompose plant material, animal corpses and excreta to renew soil fertility. By recyc- ling the detritus of plants and animals they constantly renew the sup- plies of oxygen, carbon dioxide, nitrates and even water, on which all life on this planet depends. Microbes are an intimate and essential part of the lives of all higher organisms, including ourselves. That, in outline, was – and still is – the principal message of my book. Since the days of my first edition I sense that awareness of microbes has become marginally more widespread among the general public. Perhaps my book helped a little. But awareness does not necessarily imply understanding. Thinking people all over the world have come to recognize the drastic impact the human popula- tionexplosionishavingonourplanetaryenvironment;intime,Ihope, they will also realize that microbes can often provide the bases of eco- nomic and environmental remedies, whereby ecological disaster can becontainedwhileMankindgainstimetocopewithitsownfecundity. But as well as being economic and social, my message is intellec- tual. The world of microbes is intrinsically fascinating to the inquir- ing mind because, collectively, these seemingly primitive creatures encompass all the processes of which living cells are capable. Their range of biochemical and biophysical abilities is enormously wider than those that we encounter among higher organisms. I have devel- oped this theme further in another book, The Outer Reaches of Life:as a group they define the limits of terrestrial life, and provide hints of how things may once have been on Earth – and how they could well be at present, elsewhere in the universe. Finally, as in earlier editions, I thank all those who drew my attention to occasional errors and mis- prints – I fondly hope that none has escaped the net this time. I am especially grateful to my wife, who has patiently read the revisions and, where necessary, sorted out my sometimes roundabout writing. John Postgate Lewes, UK 1 Man and microbes This is a book about germs, known to scientists as microbes (or to some, who cannot use a short word where a long one exists, as micro- organisms). These creatures, which are largely invisible, inhabit every place on Earth where larger living creatures exist; they also inhabit many parts of the Earth where no other kinds of organism can survive for long.