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Microbiota (human)

Microbial flora harbored by normal, healthy individuals. A number of microorganisms have become adapted to a particular site or ecologic niche in or on their host. Some are normal residents that are regularly found, and if disturbed will rapidly reestablish themselves; others are transient microorganisms that may colonize the host for short periods but are unable to permanently colonize. The normal fetus is sterile, but during and after birth the infant is exposed to an increasing number of microorganisms. Subsequently, those organisms best adapted to survive and colonize particular sites establish themselves and become predominant. Physiologic factors such as the availability of nutrients, temperature, moisture, pH, oxidation-reduction potential, and resistance to local antibacterial substances play an important role in determining the ability of a microorganism to become established at a particular site. The normal indigenous microbial flora is exceedingly complex, consisting of many different species of bacteria, fungi, viruses, and protozoa. The great majority of these commensal and symbiotic organisms are bacteria and fungi.

The indigenous microorganisms play an important role by protecting the normal host from invasion by microorganisms with a greater potential for causing disease. They compete with the pathogens for essential nutrients and for receptors on host cells by producing bacteriocins and other inhibitory substances, making the environment inimical to colonization by pathogens.

In the healthy individual the morphologic integrity of the body surface provides a very effective first line of defense. The intact skin is an efficient physical barrier that can be penetrated by very few microorganisms. The secretion of specific antimicrobial substances and bactericidal fatty acids by the sebaceous glands also retards microbial invasion.

Mucosal surfaces also provide a mechanical barrier in the respiratory, gastrointestinal, and genitourinary tracts. These surfaces are bathed in secretions with antimicrobial activity. In the respiratory tract, mechanical cleansing is accomplished by the cough and mucociliary action. Recurrent infections of the sinuses, middle ear, bronchial tract, and lungs occur in individuals who have an impairment of ciliary activity. These infections are usually caused by Staphylococcus pneumoniae and Haemophilus influenzae, the more virulent pus-forming organisms found in the nasopharynx. Defects in ciliary activity also cause bacterial respiratory infections in cigarette smokers and heavy alcohol drinkers. See Staphylococcus

Once the natural barriers of the skin and mucous membranes are breached, the next major line of defense is the polymorphonuclear leukocytes. Individuals with disorders of these phagocytic cells have an increased incidence of serious infections with their indigenous microflora.

The complement system is another nonspecific mechanism of the body for the elimination of invading microorganisms. Complement proteins in conjunction with organs of the reticuloendothelial system (spleen, liver, and bone marrow) play a key role in the removal of encapsulated bacteria from the bloodstream. Splenectomized individuals and those with a nonfunctioning spleen because of sickle cell disease have an increased incidence of fulminating infections caused by S. pneumoniae, H. influenzae, Neisseria meningitidis, and recently recognized unusual organisms. See Complement



a genus of plants of the family Cupressaceae (cypress). There is one species, Microbiota decussata, which is a monoecious dwarf evergreen shrub. It is 1–1.5 m high and has widely spreading branches. The needles on fertile shoots are scaly or imbricate, while those on young sprouts are acicular. The anther spikelets are oval and yellow. The small, monospermous cones are globose or ovate and consist of two to four scales. The seed itself is oval, smooth, and exalate. The plant grows in areas with severe climates on barren rocky soils, such as those found on the mountain tops and passes of Sikhote-Alin’, at elevations of 900–1,200 m. A rare plant, it is protected by law.


Kurentsova, G. E. Reliktovye rasteniia Primor’ia. Leningrad, 1968.
References in periodicals archive ?
Moreover, patients enrolled in randomized controlled trials do not represent the IBD patient population due to strict inclusion criteria.[9] These uncertainties emphasize the need for an individualized patient-based approach based on an integrated 'omics' approach incorporating genetic, microbiotic information with clinical and environmental data.
Each microbiotic species in the biome transforms that energy into new molecules, which may signal messages to physiological systems of the host.
What you may already know of the mi-crobiome is probably related to digestive-aiding probiotics, made up of microbiotic organisms that help maintain a healthy "gut culture and the negative effects of broad-spectrum antibiotics on the body's "good" bugs.
Metagenomic epidemiology is a multi-layered approach that considers the entire microbiotic context for environmental antibiotic resistance by characterizing simultaneously the different levels of microbiome complexity that drive antibiotic resistance including ARGs, genetic vectors, and the species in which these genes occur (Baquero 2012).
Zhang, "The microstructure of microbiotic crust and its influence on wind erosion for a sandy soil surface in the Gurbantunggut Desert of Northwestern China," Geoderma, vol.
Considering the types of ligand that activate these receptors, it is not surprising that some participate in the microbiotic regulation of the immune system and serve as regulators themselves.
(2) Although researchers at present are not sure as to whether antibiotics are indeed carcinogenic and/or directly cause cancer, or cancers develop as a result of their excess use, it is acknowledged that antibiotics often tend to damage and/or upset the natural balance of the body's protective intestinal "microbiotic" milieu.
These mechanisms include metabolic impairment, vascular changes in periodontium, changes of microbiotic flora in periodontal pocket and functional disorders of leukocytes.
When out of balance, the microbiotic environment may play a role in the development of obesity, ulcerative colitis, Crohn's disease, colorectal cancer, irritable bowel syndrome, celiac disease and other conditions.
One theory that requires additional research is that interactions between the intestinal microbes and isoflavones in the developing gut could affect development of the immune system and the long-term microbiotic environment of the individual.
However, some species like Paronychia chartacea may depend on delicate microbiotic associations with the soil, such as soil crusts, that may be destroyed by animal-induced disturbance (Hawkes and Flechmer, 2002).
Marlene - who runs courses on microbiotic eating and healthy living - says people should not let any genetic or hereditary problems define them.