Microbiome

from Wikipedia, the free encyclopedia
Microorganisms colonizing human skin (skin microbiome): Distribution over the body regions

The terms microbiome and microbiota ( Greek μικρός mikrós 'small', Greek βίος bios 'life') denote in the broadest sense the entirety of all the microorganisms on earth ( biome ) that colonize the earth's crust , water and the earth's atmosphere .

In a narrower sense, the totality of all microorganisms is meant that colonize a multicellular living being naturally (i.e. without triggering disease symptoms).

The mycobiome is the totality of all fungi contained in the microbiome.

Human microbiome

The human microbiome consists of bacteria (single cells) and fungi (these are usually smaller cell clusters). According to current estimates, it comprises around 39 trillion of these microorganisms; this is in the order of magnitude of the cell count of an adult “standard person” (30 trillion). Most of these microorganisms live in the intestinal tract ( intestinal flora ). In addition, the skin surface ( skin flora ) and the mucous membrane of all cavities in the human body that are directly or indirectly connected to the outside world are also populated, such as the oral cavity , nasal cavity , paranasal sinuses , tympanic cavities , vagina and the like. a. Fungi have even been found in the pancreatic duct , which opens into the duodenum . Bacteria often form colonies in the form of biofilms on the mucous membranes . Certain fungi tend to develop network-like structures.

The skin and mucous membranes form a natural barrier, and if they are damaged or damaged, germs from the microbiome can penetrate the tissue of the human body or even the bloodstream and cause diseases. A similar risk situation arises when the human immune system is weakened by drugs that are intended to counteract transplant rejection .

Many microorganisms in the microbiome are only commensals . For others, a symbiotic relationship with their host , humans, has developed through long-term adaptation in the course of evolution . The prerequisites for this are complex and multi-layered relationships on the level of metabolic processes that are reflected in regulatory, intracellular and molecular genetic levels.

Contrary to popular belief, the term “microbiome” was not first coined by Joshua Lederberg , but it was popularized. The term microbiome was used and defined by various researchers much earlier. After the end of the human genome project, Lederberg claimed that the microorganisms that colonize humans must also be taken into account, as they are part of the human metabolic system and have a significant influence on humans. In addition to the utilization of ingested food, the intestinal microbiome is assigned many other important functions, including the synthesis of vital vitamins such as B1 , B2 , B6 , B12 and K , the production of short-chain fatty acids such as acetic acid (acetate anion ) and butyric acid (butyrate anion) , which serve as an energy source for the intestinal mucous membrane cells and help determine the intestinal milieu, the promotion of intestinal peristalsis via short-chain fatty acids, the fight against inflammation, the detoxification of foreign substances, the support of digestion by breaking down food components that are difficult to digest (fiber), the stimulation of the immune system , the displacement of pathogens and more. Changes in the intestinal microbiome are associated with diseases such as intestinal inflammation, colon tumors and cancer , obesity , metabolic syndrome , arthritis , exocrine pancreatic insufficiency and also certain forms of autism and Alzheimer's disease . Animal experiments show that an altered, unfavorable microbiome can lead to states of fear or influence the extent of fear and thus appear to be largely responsible for mental health.

research

The human microbiome is part of intensive research and is not yet fully understood. The high throughput - gene sequencing allows complex ecological conduct studies. The challenges in research shaped by technical progress are data evaluation and their interpretation.

In December 2007, the NIH launched a scientific project called the Human Microbiome Project in the USA to sequence all the genomes of the microorganisms that colonize humans. The investigation is based on samples from the mouth, throat and nose, from the skin, the digestive tract and the urogenital tract of women. A free database has been set up to facilitate collaboration between the groups.

In the meantime, separate microbiomes are also considered, each of which only encompasses part of the human body (oral cavity, skin surface). For example, in early 2008 the oral microbiome was tackled by the National Institute of Dental and Craniofacial Research (NIDCR) in collaboration with researchers from other countries. It already includes 600 microorganisms. The researchers gradually organize these microorganisms into a family tree, which was made possible by sequencing the 16S rRNA . They hope this will give them a better understanding of their role in the development of tooth decay or various digestive disorders.

See also

literature

Popular science

Web links

Wiktionary: microbiome  - explanations of meanings, word origins, synonyms, translations
  • Human microbiome project [1]
  • NIH human microbiome project. Retrieved March 9, 2018 [2]
  • Joshua Lederberg: The World Wide Web of Microbiology . (translated into German) On: project-syndicate.org from December 1, 2000; last accessed on September 19, 2015.

Individual evidence

  1. ↑ Urs Jenal: Man and his microorganisms. Interactions between illness and wellbeing. (How many people is a person?) Author at the Biozentrum of the University of Basel . → Full text PDF ( Memento of the original from March 4, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.biozentrum.unibas.ch
  2. ↑ bioRxiv : 10.1101 / 036103v1 ( preprint full text)
  3. ↑ Werner Bär: Physiological bacterial flora: resistance to colonization, endogenous opportunist infections; Probiotics. In Helmut Hahn, Stefan HE Kaufmann, Thomas F. Schulz, Sebastian Suerbaum: Medical Microbiology and Infectiology. Springer, Berlin / Heidelberg / New York 2009, ISBN 978-3-540-46359-7 , p. 26 f.
  4. ^ Susan L. Prescott: History of medicine: Origin of the term microbiome and why it matters . In: D. Raoult (Ed.): Human Microbiome Journal Volume . tape 4 , June 2017, ISSN  2452-2317 , p. 24-25 .
  5. ^ Whipps JM, Lewis K., Cooke RC: Mycoparasitism and plant disease control . In: Burge MN (Ed.): Fungi in Biological Control Systems . Manchester University Press, Manchester, New York 1988, ISBN 978-0-7190-1979-1 , doi : 10.1071 / app9890106c ( google.de [accessed April 10, 2019]).
  6. ↑ H. Köppen: Gut flora & microbiome . In: Website Praxiszentrum-Leipzig . ( praxiszentrum-leipzig.de [accessed on May 22, 2017]).
  7. ↑ Dirk Haller: Nutrition and Microbiome , ZIEL - Research Center for Nutrition and Food Sciences Biofunctionality Unit, Technical University of Munich , Lecture Series Winter 2014-15, University of Hamburg
  8. ^ Scientists Launch First Comprehensive Database of Human Oral Microbiome. NIH press release, March 25, 2008.