𝐌𝐢𝐜𝐫𝐨𝐛𝐢𝐨𝐭𝐚

A microbiota is "the ecological community of commensal, symbiotic and pathogenic microorganisms that literally share our body space". Joshua Lederberg coined the term, emphasising the importance of microorganisms inhabiting the human body in health and disease. Many scientific articles distinguish microbiome and microbiota to describe either the collective genomes of the microorganisms that reside in an environmental niche or the microorganisms themselves, respectively. However, by the original definitions these terms are largely synonymous.

The human body contains over 10 times more microbial cells than human cells, although the entire microbiome only weighs about. Bacteria are 10-100 times smaller than human cells. Some regard the microbiome as a "newly discovered organ" since its existence was not generally recognized until the late 1990s and it is understood to have potentially overwhelming impact on human health. Humans are colonized by many microorganisms; the traditional estimate was that humans live with ten times more non-human cells than human cells inhabit the skin, mouth, nose, digestive tract and other areas of the human body. Modern techniques for sequencing DNA have enabled researchers to find the majority of these microbes - the majority of them cannot be cultured in a lab using current techniques.

The human microbiome may have a role in auto-immune diseases like diabetes, rheumatoid arthritis, muscular dystrophy, multiple sclerosis, fibromyalgia, and perhaps some cancers. A poor mix of microbes in the gut may also aggravate common obesity. Since some of the microbes in the human body can modify the production of neurotransmitters known to occur in the brain, it may also relieve schizophrenia, depression, bipolar disorder and other neuro-chemical imbalances. The microbes being discussed are generally non-pathogenic (they do not cause disease unless they grow abnormally); they exist in harmony and symbiotically with their hosts.