Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Human skin harbors completely unknown bacteria

07.02.2007
New study finds skin has many more types of bacteria than previously thought

It appears that the skin, the largest organ in our body, is a kind of zoo and some of the inhabitants are quite novel, according to a new study. Researchers found evidence for 182 species of bacteria in skin samples. Eight percent were unknown species that had never before been described.

It is the first study to identify the composition of bacterial populations on the skin using a powerful molecular method. Not only were the bacteria more diverse than previously estimated, but some of them had not been found before, says Martin J. Blaser, M.D., Frederick King Professor and Chair of the Department of Medicine and Professor of Microbiology at NYU School of Medicine, one of the authors of the study.

"The skin is home to a virtual zoo of bacteria," he says. This study is published February 5, 2007, in the online edition of the Proceedings of the National Academy of Sciences.

... more about:
»16S »Blaser »Gao »Molecular »phyla »sample »swab

The researchers analyzed the bacteria on the forearms of six healthy subjects; three men and three women. "This is essentially the first molecular study of the skin," says Dr. Blaser. The skin has been, he says, terra incognita, an unknown world that he and his colleagues have set out to understand much like explorers.

"There are probably fewer than ten labs in the U.S. looking at this question," says Dr. Blaser. "It is very intensive work," he adds. Zhan Gao, M.D., senior research scientist in Dr. Blaser's lab, led the research, which took more than three years to complete.

Some of the bacteria on the skin appear to be more or less permanent residents; others are transient, according to the study.

This research is part of an emerging effort to study human microbial ecology. Dr. Blaser's laboratory has previously examined the bacterial population in the stomach and the esophagus. "Many of the bacteria of the human body are still unknown," he says. "We all live with bacteria all our lives and occasionally we smile, so they're not that bad for us."

The most numerous cells in our body are microbial—they outnumber our cells 10 to 1. The body has microbes native to the body, including the skin, and these populations change according to how we live, he says. "Ultimately what we want to do is compare disease and health," says Dr. Blaser. Keeping bacterial populations in our body stable may be part of staying healthy, he says.

In the new study, the researchers took swabs from the inner right and left forearms of six individuals picking the region halfway between the wrist and the elbow for its convenience. "It's not where they wash their hands," explains Dr. Blaser. "And they don't have to undress." The researchers wanted to be able to compare two similar parts of the body. Because they also wanted to study change over time, they took swabs from four of the individuals 8 to10 months after the first test.

Roughly half, or 54.4%, of the bacteria identified in the samples represented the genera Propionibacteria, Corynebacteria, Staphylococcus and Streptococcus, which have long been considered more or less permanent residents in human skin.

The six individuals differed markedly in the overall composition of the bacterial populations on their skin. They only had four species of bacteria in common: Propionibacterium acnes, Corynebacterium tuberculostearicum, Streptococcus mitis, and Finegoldia AB109769. "This is a surprise," says Dr. Gao. "But many things affecting the skin affect bacteria, such as the weather, exposure to light, and cosmetics use."

Almost three-quarters, or 71.4%, of the total number of bacterial species were unique to individual subjects, suggesting that the skin surface is highly diversified in terms of the bacteria it harbors, according to the study.

Three bacterial species were only found in the male subjects: Propionibacterium granulosum, Corynebacterium singulare, and Corynebacterium appendixes. While the sample is too small to draw conclusions, the scientists believe that women and men may harbor some different bacterial species on their skin.

In each individual, the bacterial populations varied over time while revealing a core set of bacteria for each individual. "The predominant bacteria don't change much," says Dr. Gao. "But the more transient bacteria did change over time," she says.

"What that suggests," adds Dr. Blaser, "is that there is a scaffold of bacteria present in everybody's skin. Some stay and others come and go."

Finding the method

To obtain a sample Dr. Gao rubbed a swab on each individual's forearms. "We didn't tell them to be particularly clean, we just made sure they didn't take antibiotics up to one month prior to the test," Dr. Gao explains. She chose three men and three women to have a balance of genders. She set up a clean room so the samples didn't risk contamination.

Traditionally, bacteria are cultured in the lab in petri dishes, which contain a medium to grow bacteria. But the method leads to inaccuracies, she explains, because only a fraction of bacteria in a sample grow in that medium. So the team used a powerful molecular method that involved extracting a subunit of genetic material called 16S ribosomal DNA from the samples. "It is kind of a common currency, it's a conserved gene," says Dr. Blaser. Another advantage is that there is a large database of 16S ribosomal DNA available to scientists.

The ambitious task for this study was to gather samples, prepare them, amplify the bacteria creating colonies of each single species of bacteria present in the skin samples. Then Dr. Gao used established tools—primers—to pick out the species-specific genetic regions in the bacteria. After sequencing those regions, the 16S ribosomal DNA (rDNA) in each colony, she consulted 16S rDNA databases to determine the bacterial species present in each sample. Many bacteria in the database only exist as sequences and have nether been named or extensively studied. Those are termed SLOTUs, or species-level taxonomic units.

Taxonomy and the study results

To distinguish organisms from one another, biologists group and categorize them. Species or SLOTUs are small categories. There are larger groupings such as genera and phyla. Humans, for example, belong to the phylum chordata, the genus Homo and the species Homo sapiens.

The molecular method used in this study revealed differences between the bacterial populations in individuals. Other methods had previously not shown those differences.

The team found a total of 182 species or SLOTUs and 91 genera of bacteria in the skin samples.

The samples yielded mainly three phyla of bacteria: Actinobacteria, Firmicutes, and Proteobacteria. Ninety-four point six percent of the bacteria were in these phyla. These phyla were found in all six tested individuals. When compared with earlier studies, the researchers found that these three phyla are also dominant in the esophagus and the stomach. In terms of bacterial species, however, the insides of the body, for example the stomach, and the exterior of the body, the skin, show vast differences in bacterial populations.

Skin condition can change markedly due to a variety of factors such as climate, diet, personal hygiene, and disease. But skin is never devoid of bacteria, particularly its more permanent residents. That is not bad news, after all, in healthy individuals these bacteria are not pathogens. "Without good bacteria, the body could not survive," says Dr. Gao.

The next step for the research team is to look at diseased skin. "We plan to ask the question: Are the microbes in diseased skin, in certain diseases like psoriasis or eczema, different than the microbes in normal skin?" says Dr. Blaser.

Jennifer Berman | EurekAlert!
Further information:
http://www.nyumc.org

Further reports about: 16S Blaser Gao Molecular phyla sample swab

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>