Science - April 21, 2011

News in Nature: 'gut flora are a distinct ecosystem'

Human beings can be divided into three groups, according to the composition of the bacteria in their intestines. This discovery is expected to make personalized nutrition and medication a real possibility.

E-coli bacteria in the intestine
Just like blood groups, the three 'enterotypes' are found all over the world, irrespective of age, eating habits or race.
This finding was published in the Nature of 20 April in an article to which four Wageningen scientists at the Laboratory for Microbiology contributed. 'On the basis of all the DNA sequences in intestinal samples from people in Europe, the US and Japan, we could distinguish three main groups, each with their own typical bacteria populations', says Willem de Vos, professor of microbiology and one of the co-authors. 'This could explain why the absorption of food and medicines in the intestines varies from person to person.'
Ecosystem
Our intestinal bacteria are vital as they convert our food into useful substances such as vitamins. At the same time, these single-cell organisms protect us against attacks by pathogens. In exchange for these services, we provide our bacteria with food and a home. Until recently it was difficult to study gut bacteria because they could not survive in a laboratory. But with current DNA techniques, scientists can measure the total genetic information about all the microbiota in one sample. This makes it possible to identify the bacteria species and get a picture of the combination of bacteria present. The gut bacteria, in total 100,000 billion of them, make up a community that has all the characteristics of an ecosystem. Just like an ecosystem in the natural world, the microbiota ultimately reach a stable balance, with dominant species. And this enables microbiolists to distinguish three  bacteria ecosystems, or 'enterotypes'.
Intestinal diseases
The combination of intestinal bacteria has a big influence on the nutrients produced. What is more, some of the bacteria absorb nutrients and medicines more effectively than others. On the basis of the enterotype present, with its particular combination of species, you could match a diet, and even medication, more precisely to an individual's needs. 'The use of microbiota for diagnostic purposes is really taking off', declares De Vos. 'The presence of certain species of bacteria can help with early detection of certain diseases.'

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