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.
Escherichia coli, one of the many species of bacteria present in the human gut
Composition and distribution of gut microbiota in human body
Candida albicans, a dimorphic fungus that grows as a yeast in the gut
Illustration showing the developmental colonization of gut microbiota
A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells.
A cluster of Escherichia coli bacteria magnified 10,000 times
Mahavira postulated the existence of microscopic creatures in the 6th century BC
Antonie van Leeuwenhoek was the first to study microscopic organisms.
Lazzaro Spallanzani showed that boiling a broth stopped it from decaying.
