APA Dictionary of Psychology

microbiome

Updated on 03/06/2026

the community of microorganisms and their collective genetic material inhabiting a defined ecological environment (e.g., the human body or gut). In the human microbiome, these include bacteria, viruses, fungi, protists, and microscopic eukaryotes such as mites. The gut microbiome, the most extensively studied human microbial community, plays a central role in digestion, nutrient metabolism, vitamin synthesis, immune system development, and maintenance of the intestinal barrier. Alterations in microbiome composition or function, known as dysbiosis, have been associated with a range of diseases, including inflammatory bowel disease, metabolic and autoimmune disorders, and other systemic conditions. Also called microbiota.
the community of microorganisms and their collective genomes inhabiting a particular environment.

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