Gut microbiota, gut microbiome, or gut flora are the microorganisms, including bacteria, archaea, fungi, and viruses, that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the gut microbiota. The gut is the main location of the human microbiome. The gut microbiota has broad impacts, including effects on colonization, resistance to pathogens, maintaining the intestinal epithelium, metabolizing dietary and pharmaceutical compounds, controlling immune function, and even behavior through the gut–brain axis.

In the present book, twelve typical literatures about gut microbiome published on international authoritative journals were selected to introduce the worldwide newest progress, which contains reviews or original researches on gut microbiome. We hope this book can demonstrate advances in gut microbiome as well as give references to the researchers, students and other related people.