In this Journey to Microbial Worlds we present the diversity of microorganisms, from the state of fossil microbes in Archaean age rocks to the possibilities of extraterrestrial life. This volume discusses the extremophiles living in harsh environments (from our anthropocentric point) and describes them in considerable detail. Some chapters also review topics such as symbiosis, bacterial luminescence, methanogens, and petroleum-grown cells. The final chapters of this book shed new light on astrobiology and speculate on extremophiles as candidates for extraterrestrial life. All chapters are updated to the latest research level.In this Journey to Microbial Worlds we present the diversity of microorganisms, from the state of fossil microbes in Archaean age rocks to the possibilities of extraterrestrial life. This volume discusses the extremophiles living in harsh environments (from our anthropocentric point) and describes them in considerable detail. Some chapters also review topics such as symbiosis, bacterial luminescence, methanogens, and petroleum-grown cells. The final chapters of this book shed new light on astrobiology and speculate on extremophiles as candidates for extraterrestrial life. All chapters are updated to the latest research level.Dedication. Foreword; J.T. Staley. Preface; J. Seckbach. Acknowledgements. I: General Diversity. 1. A Vista into the Diverse Microbial Worlds: An Introduction; J. Seckbach, A. Oren. 2. Diversity of Fossil Microorganisms in Archaean-Age Rocks; F. Westall, M.M. Walsh. 3. Prokaryotic Diversity; F.A. Rainey, N. Ward-Rainey. 4. Molecular Biology and Genetic Diversity of Microorganisms; V. Torsvik, et al. II: Introduction to Extremophiles. 5. Bacterial Habitats of Extremophiles; M.T. Madigan. 6. Anaerobes from Extreme Environments; B. Ollivier, et al. III: Thermophiles and Acidophiles. 7. Sulfur Metabolism Among Hyperthermophiles; K.M. Noll, S.E. Childers. 8. l&