Microorganisms play a major role in the geobiology and geochemistry of the planet, forming the basic stage in the food chain, and thus sustaining the existence of higher evolutionary life. The continuing interaction between these living organisms and the environment, combined with their exploitation by man, shape the material world. Over the past few years our understanding has increased considerably by means of new technology and the emergence of paradigms which enable the microbiologist to view the microbial world, and its significance to life, with new eyes. The book reflects these exciting developments by combining the basics of science with the most up-to-date new material. It will be valuable as a textbook and reference guide for students and professionals in microbiology, freshwater and marine biology, soil science, environmental biology, and planning.