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.

There are trillions of microbes in the human microbiome, although the entire microbiome only accounts for about for 1-3% total body mass, with some weight-estimates ranging as high as 3 pounds (approximately 48 ounces or 1,400 grams). Research into the role that microbiota in the gut might play in the human immune system started in the late 1990s. The microbiome of the gut has been characterised as a "forgotten organ", and the possibility has been raised that "the mammalian immune system, which seems to be designed to control microorganisms, is in fact controlled by microorganisms". 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 regulation of some neurotransmitters, it may be possible to use certain microorganisms to supplement treatments for depression, bipolar disorder and other stress-related psychiatric disorders.

Human microbiota

The human microbiota is the aggregate of microorganisms, a microbiome that resides on the surface and in deep layers of skin (including in mammary glands), in the saliva and oral mucosa, in the conjunctiva, and in the gastrointestinal tracts. They include bacteria, fungi, and archaea. Micro-animals which live on the human body are excluded. The human microbiome refers to their genomes.

Previous estimates calculated that microbes outnumber human cells 10 to 1, however, the comparative total cell counts may be much closer and that "each defecation event may flip the ratio to favor human cells over bacteria."

Some of these organisms perform tasks that are known to be useful for the human host; for most, the role is not well understood. Those that are expected to be present, and that under normal circumstances do not cause disease, are deemed members of the normal flora or normal microbiota.

Most of the microbes associated with humans appear to be not harmful at all, but rather assist in maintaining processes necessary for a healthy body. A surprising finding was that at specific sites on the body, a different set of microbes may perform the same function for different people. For example, on the tongues of two people, two entirely different sets of organisms will break down sugars in the same way. This suggests that medical science may be forced to abandon the "one only" microbe model of infectious disease, and rather pay attention to functions of groups of microbes that have somehow gone awry.

Microbiota decussata

Microbiota is a monotypic genus of evergreen coniferous shrub in the cypress family Cupressaceae, containing only one species, Microbiota decussata (Siberian carpet cypress, Russian arbor-vitae). The plant is native and endemic to a limited area of the Sikhote-Alin mountains in Primorskiy Krai in the Russian Far East. The name causes much confusion because of other meanings for the word "microbiota," but the genus name was derived from "micro," meaning "small" + "Biota," name for a closely related conifer, a species formerly called Biota orientalis, now renamed Platycladus orientalis.

Taxonomy

The monotypic taxon Microbiota was discovered in 1923, but political secrecy in the former Soviet Union prevented any knowledge of its existence outside the country for around 50 years.

It is generally accepted as being a distinct genus. It has also been suggested, but not widely followed, that Microbiota could be included in the closely related genus Platycladus. Other fairly close relatives are the genera Juniperus and Cupressus.