Abstract: The human gastrointestinal (GI) tract harbours a complex and dynamic population of microorganisms, the gut microbiota, which exerts a marked influence on the host during homeostasis and disease. Gastrointestinal bacteria play a crucial role in maintaining immune, metabolic homeostasis and protecting against pathogens. Altered gut bacterial composition has been associated with the pathogenesis of many inflammatory diseases and infections. Recently, a large number of studies have revealed the influence of different microbiota on human gastrointestinal system diseases, such as gastritis, inflammatory bowel disease and cancer, etc. Human gastrointestinal microbiota and their related metabolites are also considered to be potential therapeutic targets for a variety of diseases. This review summarizes our current understanding of the development and composition of the human GI microbiota, and its impact on gut integrity and host health, underlying the need for mechanistic studies focusing on host microbe interactions.

Key words: gastrointestinal, microbiota, metabolite, gastrointestinal system diseases