CONCEPT
Microbiome
The community of microorganisms — bacteria, fungi, viruses — colonizing every surface of a multicellular organism, performing essential metabolic and immune functions, making the organism a holobiont rather than an individual.
The microbiome is the ecological community of microorganisms residing in and on a multicellular host. The human microbiome comprises trillions of bacteria, archaea, fungi, and viruses inhabiting the gut, skin, respiratory tract, urogenital tract, and oral cavity. These microorganisms outnumber human cells and perform functions essential to host health: digesting complex carbohydrates, synthesizing vitamins (B12, K), training the immune system, outcompeting pathogens, and even producing neurotransmitters affecting mood and cognition. The microbiome is not a passive passenger; it is an active partner in the holobiont. Its composition is shaped by host genetics, diet, environment, and antibiotic exposure, and its dysregulation (dysbiosis) is implicated in metabolic disease, immune dysfunction, obesity, depression, and inflammatory disorders. Margulis treated the microbiome as evidence that the organism is a community, that the boundary between self and other is negotiated rather than fixed, and that health depends on ecosystem management rather than individual purity.
In The You On AI Field Guide
The human gut microbiome alone contains roughly one hundred trillion