This important new textbook is the culmination of 25 years of teaching microbial physiology and metabolism to undergraduate and graduate students. A theme that guided the writing of this textbook is that students must not simply memorize material such as metabolic pathways and bioenergetic models, but they should understand the underlying principles. To that end, similarities and contrasts between metabolic pathways and other physiological activities are pointed out through the textbook, and separate sections are devoted to describing the chemistry and physics for key reactions. In addition to describing physiological and metabolic features common to most microorganisms, the textbook also offers a modern perspective on metabolic diversity. Topics included in this text are: cell structure, growth, bioenergetics, electron transport, photosynthesis, metabolic regulation, intermediary metabolism, cell wall biosynthesis, fermentations, C1 metabolism, inorganic metabolism, solute transport, protein secretion, homeostasis, and two-component as well as other signaling systems. Each chapter concludes with a summary emphasizing the major points covered, and a set of study questions to test the students' mastery of the material.