Clipping Board » New Knowledge and the Unknown of Life ─ Life will always bring you surprises and wonders.
China Times 2008.05.24
By Yin Dehan / New York Times, 23rd Report
Even when thoroughly washed, a square centimeter of skin on the inner elbow contains 1 million bacteria. But there's no need to worry; these bacteria are not harmful. They are what biologists call "commensals," which can have a mutually beneficial relationship with the human body.
According to a new study by the U.S. National Human Genome Research Institute, the bacteria on human skin can be divided into six groups, with as many as 130 different species.
This study, led by Dr. Julie Segre of the institute, is part of the Human Microbiome Project. The findings were published on the 23rd in the journal Genome Research.
The "human microbiome" refers to all the microorganisms (including bacteria, archaea, fungi, parasites, and viruses) that live on and inside the human body. Humans rely on these microorganisms for a variety of essential services, including digestion. Therefore, humans should actually be considered "superorganisms," where the number of bacterial cells is ten times that of human cells.
Segre estimates that there are at least 20 different communities of bacteria on human skin, each with a unique set of commensals. For example, the bacteria Segre found on the inner elbow are completely different from those found on the inner wrist by other research teams. However, among the five individuals Segre studied, the bacteria on their inner elbows were largely the same, suggesting that the environment of the inner elbow (including nutrients and moisture) is particularly suitable for the growth of this bacterial community.
Another study by the Washington University School of Medicine in St. Louis found that among 70 known families of bacteria, most gut bacteria belong to just two of these families. These gut bacteria perform various essential functions, including breaking down complex sugars or converting hydrogen into methane.
This study analyzed the feces of 59 different mammalian species and found that the composition of their gut bacteria is closely related to their diet. For instance, carnivores, herbivores, and omnivores each have a distinct set of gut bacteria.
Both Dr. Segre's research and the Washington University study consistently found that whether in humans or animals, the bacteria have adapted remarkably well to their hosts, so much so that they may contribute to the evolution of different species.
In an interview, Segre said, "We have evolved with the bacteria on our bodies."
The Human Microbiome Project is vast and still in its early stages, but it has already confirmed that the total number of bacterial genes in the human body is at least 100 times that of the human genome (approximately 20,000 genes). The next step for the project is to analyze the different bacterial communities in various parts of the human body. Another goal is to understand how pathogens can usurp the position of commensals on the skin or in the gut, leading to disease.
Source: http:/ / news. chinatimes. com/ 2……0504+112008052400481,00. html
Superorganism: Coevolution of Humans and Symbiotic Bacteria
By Yin Dehan / New York Times, 23rd Report
Even when thoroughly washed, a square centimeter of skin on the inner elbow contains 1 million bacteria. But there's no need to worry; these bacteria are not harmful. They are what biologists call "commensals," which can have a mutually beneficial relationship with the human body.
According to a new study by the U.S. National Human Genome Research Institute, the bacteria on human skin can be divided into six groups, with as many as 130 different species.
This study, led by Dr. Julie Segre of the institute, is part of the Human Microbiome Project. The findings were published on the 23rd in the journal Genome Research.
The "human microbiome" refers to all the microorganisms (including bacteria, archaea, fungi, parasites, and viruses) that live on and inside the human body. Humans rely on these microorganisms for a variety of essential services, including digestion. Therefore, humans should actually be considered "superorganisms," where the number of bacterial cells is ten times that of human cells.
Segre estimates that there are at least 20 different communities of bacteria on human skin, each with a unique set of commensals. For example, the bacteria Segre found on the inner elbow are completely different from those found on the inner wrist by other research teams. However, among the five individuals Segre studied, the bacteria on their inner elbows were largely the same, suggesting that the environment of the inner elbow (including nutrients and moisture) is particularly suitable for the growth of this bacterial community.
Another study by the Washington University School of Medicine in St. Louis found that among 70 known families of bacteria, most gut bacteria belong to just two of these families. These gut bacteria perform various essential functions, including breaking down complex sugars or converting hydrogen into methane.
This study analyzed the feces of 59 different mammalian species and found that the composition of their gut bacteria is closely related to their diet. For instance, carnivores, herbivores, and omnivores each have a distinct set of gut bacteria.
Both Dr. Segre's research and the Washington University study consistently found that whether in humans or animals, the bacteria have adapted remarkably well to their hosts, so much so that they may contribute to the evolution of different species.
In an interview, Segre said, "We have evolved with the bacteria on our bodies."
The Human Microbiome Project is vast and still in its early stages, but it has already confirmed that the total number of bacterial genes in the human body is at least 100 times that of the human genome (approximately 20,000 genes). The next step for the project is to analyze the different bacterial communities in various parts of the human body. Another goal is to understand how pathogens can usurp the position of commensals on the skin or in the gut, leading to disease.
Source: http:/ / news. chinatimes. com/ 2……0504+112008052400481,00. html