哈哈哈其實之前注意這議題已經很久了，沒想到真的有人在做研究阿 囧
如果能釐清一些交互作用的機制肯定會非常有趣
引用網址 http://www.sciencenews.org/view/generic/id/49242/title/Bacteria_flourish_in_favorite_ecosystems_on_the_human_body
Bacteria flourish in favorite ecosystems on the human body
Studyoffers most comprehensive inventory yet of the human microbiome and abasis for understanding how those microbes affect health
By
Laura Sanders
Web edition : Thursday, November 5th, 2009
Like fussy first-time homebuyers, microbes in and on the humanbody choose their digs according to three strict rules: location,location, location. If the palm of the hand is a bustling metropolitancity crammed with hundreds of species, the ear canal is centralWyoming.
This variety is revealed by the mostcomprehensive inventory yet of the body’s microbial community. Reportedonline November 5 in Science, the research provides one of the mostthorough whole-body maps to date of the estimated 100 trillionindividual microbes the body harbors inside and out.
Assessingthe body’s different microbial habitats will help researchersunderstand the intimate link between the human body and the microbiome— the bacteria, fungi and viruses that live in and on the body. Thesemicrobes — estimated to outnumber human cells by at least a factor of10 — usually coexist with the human body in peaceful harmony, playingimportant roles in health, such as aiding digestion and preventingharmful infections. Understanding which microbes live where may helpscientists understand how to treat people with disorders, includingeczema and digestive disorders, that have been linked to specific kindsof bacteria.
“There’s so much unexplored territory in thehuman microbiome,” says Julia Segre, a biologist at the National HumanGenome Research Institute in Bethesda, Md. “We need these kinds ofbaseline studies to know what to expect.”
The new study,which relies on DNA sequencing for the bacterial census, provides “anoverview of the healthy human microbiota,” the researchers, led by RobKnight and Elizabeth Costello, both of the University of Colorado inBoulder, write in the report.
Over the course of threemonths, Knight and his colleagues swabbed microbe samples from 27bodily locales on or in seven to nine healthy volunteers at a time.Locations included ear canals, nostrils, mouths, lower intestines,navels, backs of knees, armpits, hair on heads, index fingers andpalms. DNA sequences told researchers how many different kinds ofbacteria resided in each spot. (Fungi and viruses, although part of themicrobiome, weren’t analyzed in the study.)
Communitiesof bacteria living in one person’s distinct nooks and crannies werevery different from each other, the team found. “It was reallysurprising to us just how little was shared at different sites on thesame subjects,” Knight says. While some places, such as the navel,forehead and armpits, were colonized with few kinds of bacteria, otherplaces, including the back of the knee, palm and forearm, had manydifferent types of bacteria all living together. In fact, most peoplehad at least one skin site with more diversity than that of themicrobe-rich gut, the team found.
Comparing thebacterial profiles of volunteers to each other, the researchers foundthat overall, the microbiomes were highly personalized. Places such asthe gut, hair, nostrils, ear canals and skin locations were verydifferent from person to person. “People seem to be colonized by verydifferent bacteria,” Knight says.
In a separateexperiment, the researchers conducted a bacterial transplantexperiment, in which the bacterial community from one locale was movedto another place (after sterilization) and tracked over several hours.This experiment tested how hospitable some body parts are to newbacteria, which are known to be sensitive to environmental factors suchas oil, moisture and pH. Forearm bacteria didn’t thrive after a move tothe forehead, the researchers found, and vice versa. Bacteria from aperson’s tongue fared well on a forearm, but didn’t flourish on theforehead, suggesting that the oily forehead may be a harsherenvironment than the relatively dry forearm for some bacteria.Interestingly, the results were similar when participants received atransplant from their own body and when participants received abacterial transplant from a different person.
