The purpose of this book is to illustrate a selection of biological prop erties of bacteria that reveal them as important living beings. We have primarily addressed readers who have had some previous educa tion in the natural sciences, and we have assumed a modest under standing of elementary chemical and biological principles. Our aim is to provide abrief survey of bacterial forms and structures, placing special emphasis on the activities of bacteria in their environment and some important interrelations within it. Bacterial ecobiology is the study of those aspects of bacteria that influence, and are in fluenced by, environmental phenomena. Some material traditionally covered in standard texts-such as medi cal bacteriology and immunology, applied bacteriology, and bacterial classification-will not be found here, because it is our opinion that these are peripheral to the idea of ecobiology and because numerous excellent treatments of this material are readily available. There is also no formal presentation ofbacterial genetics or of molecular biology per se in this book. However, mention of phenomena involved in these subjects is made where considered appropriate.

Volume 2.

Any branch of biology depends for its progress on the development of new concepts and to a lesser, but sometimes crucial, extent on the elimination of erroneous notions. Understanding the roles of bacteria required first the observation that such minute creatures existed, and subsequently the exper imental demonstrations that their presence was necessary for the occurrence of particular phenomena. In this first volume, the authors review the development of scientific understanding of the role of microbes as agents of diverse natural processes. Notably absent is a separate review of the history of microbes as agents of disease, a his tory available in many other publications. Regrettably absent is a review of the his tory of microbes as agents of inorganic transformations, a serious omission that resulted from the illness of the prospective author late in the preparation of this volume. The topic will of course be treated in later volumes, although not predominantly in a historical manner. Otherwise, the emphasis in this volume is on the history of understanding interrelationships between modes of bacterial existence and the inanimate environment. These relationships were established long be fore multicellular, differentiated or ganisms appeared as potential microbial habitats, and their recognition and elucidation contributed greatly to the widened appreciation of bacterial di versity and the importance of these simpler creatures to the physiochemical conditions of the biosphere.

Sulfate-reducing bacteria comprise a diverse and ecologically interactive group of anaerobic prokaryotes which share an extraordinary trait: growth by sulfate respiration with hydrogen sulfide as a major end-product. Sulfate-reducers are found in diverse environments ranging from estuaries to geological oil-bearing formations. They have attracted considerable scientific and commercial interest. These organisms have been actively investigated by researchers in microbial energetics, protein chemistry, ecology and more recently molecular biology. This interest has increased greatly over the past decade, and this volume presents the first book-length summary of our knowledge of sulfate-reducing bacteria in nearly 10 years. Featuring an introduction by the eminent microbiologist John Postgate and comprehensive reviews from recognized authorities, this book will be of interest to microbiologists with interests in physiology, evolution, and ecology.