Researchers identify three enterotypes in human intestinal bacteria

It would appear that in terms of composition, the intestinal bacteria of every individual can be divided into three main groups known as enterotypes. The intestinal bacteria in each enterotype organise themselves into distinct, stable clusters displaying common features. The intestinal bacteria types (which can be compared with blood groups) are not influenced by factors such as place of residence, health or age of the person concerned. The discovery of these groups provides promising opportunities for individual medicinal and dietary advice. A consortium of researchers from ten countries, including four researchers from Wageningen University, reported their findings in the 20 April (online) edition of Nature.

The international research team named MetaHIT, comprising researchers from ten countries, combined three different studies based on 39 people from three continents (Danes, French, Italians, Spaniards and Japanese and Americans), 85 individuals from Denmark and 154 Americans. Three enterotypes were identified in the intestinal bacteria of all three groups. The four researchers from Wageningen, Michiel Kleerebezem, Sebastian Tims and Erwin Zoetendal led by Professor Willem M. de Vos, used the HIT Chip (Human Intestinal Tract Chip) to focus on the group of Europeans. Advanced bioinformatic analysis came up with three recognisable enterotypes, seemingly irrespective of nationality, gender, age, health, BMI (body mass index) or incidence of chronic gut disease.

Three enterotypes

The three enterotypes show various categories of bacteria with a different impact of the gut. Enterotype 1 is dominated by the Bacteroides intestinal bacteria, which together with a few other species of bacteria, forms a distinctive cluster of gut flora. The dominant bacteria in enterotype 2 is Prevotella. And in enterotype 3, Ruminococcus is the main bacteria, along with other species such as Staphylococcus, Gordonibacter and a species discovered in Wageningen previously, Akkermansia. Enterotype 3 is the most common.

Furthermore, every cluster of bacteria has its own way of supplying energy. Enterotype 3, for example, specialises in breaking down mucin, a carbohydrate that enters the gut via our food. This allows the gut to absorb these fragments as nutrition for the body. All three enterotypes also produce vitamins, albeit in varying amounts. Enterotype 1 produces the most vitamin B7 (biotin), B2 (riboflavin) and C (ascorbic acid), and enterotype 2 produces mainly vitamin B1 (thiamin) and folic acid. Every enterotype, with its distinctive clusters of bacteria and functional differences, reflects a distinctive way of generating energy that is closely compatible with its host. It is also possible that the enterotypes may interact with their host on various levels, having an impact on the individual's health.

In March of last year, the MetaHIT consortium published the first catalogue of genes of human intestinal bacteria (also known as the second genome). These bacteria populations encode 150 times more genes than our own genome. It was shown that from a range of more than a thousand species of bacteria that live in the human gut, every individual is host to several hundred types of bacteria.

The discovery of the enterotypes will influence the fields of biology, medicine and nutrition, making it much easier to analyse an individual's needs. The research team sees future opportunities for personal and preventive dietary and medicinal advice.



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