Science - March 3, 2010

Gut bacteria reveals its genes

Genome of gut bacteria mapped. Diseases can now be traced to micro-organisms.

Micro-organisms in the intestines
The genes of a large number of micro-organisms, the microbiota, found in the human intestines have been mapped. The results have been published in Nature magazine.
The gene set is derived from gut microbiota retrieved from the excretions of 124 European individuals. With about more than three million genes, this set is 150 times larger than the human genome. According to the authors, four of whom are from the Laboratory of Microbiology of Wageningen UR, the gene set covers a large number of the most common bacteria in the human intestines.

Micro-organisms in the intestines are the Jack-of-all-trades in digestion. They help to extract energy from food by fermenting it, during which sugars are converted into fatty acids. The intestines then absorb these fatty acids. In addition, the bacteria change amino acids and vitamins chemically. 'Micro-organisms are indispensable; we wouldn't be able to survive without them', says co-author Willem de Vos, professor of microbiology. At times, it appears that these 'creatures' know exactly what the body needs. For example, the gut bacteria of a baby contain genes active in stimulating the production of folic acid, which is important for developing the nervous system. According to de Vos, this happens because the body exchanges information with the microbiota in the intestines. 'The microbes communicate with the body, which can lead to a change in the way their hereditary characteristics are expressed', says De Vos.

Intestinal problems
De Vos is pleased that the Chinese have shouldered the enormous task of deciphering the genome. 'The main message underlying the published results is that a catalogue of the potential capacity of microbiota in our abdomen is available ', says De Vos. Co-author Erwin Zoetendal sees the gene catalogue as a beginning. 'We are particularly interested in the function of the genes', he explains. The new results offer countless possibilities to trace diseases to the microbial composition and functions in the intestines. 'For example, people who suffer from chronic intestinal infections have a different microbiota composition in their intestines than that of healthy individuals', Zoetendal propounds. 'It will be interesting to find out if this is the cause or the result of the disease.' 

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