The halophilic microorganisms form a highly diverse group of organisms. They present the biochemist/physiologist with interesting questions on the strategies used to cope with high osmotic pressures exerted by hypersaline brines. They often have a strong impact on the ecosystems in which they thrive. The first section of the book presents in-depth discussions of the taxonomy, cellular properties, metabolic diversity, pigments, ion metabolism and organic osmotic solutes, properties of halophilic proteins, genetics, and biotechnological uses of halophilic microorganisms. The second section describes the occurrence and functioning of these organisms in the Great Salt Lake, the Dead Sea, solar saltern ponds, alkaline soda lakes, and other hypersaline environments worldwide. Each chapter contains an extensive list of references. No other book provides in-depth up-to-date coverage of all subjects described. The volume is intended for researchers and students interested in microbial physiology, microbial ecology, environmental sciences, and extremophilic biotechnology.