Each of us has trillions of bacteria in our guts. These communities vary greatly between individuals, but a paper published in Nature last year1 indicated that they fall into just three distinct types — enterotypes — defined by their bacterial composition (see ‘Gut study divides people into three types’). Each enterotype is characterized by relatively high levels of a single microbial genus: Bacteroides, Prevotella, or Ruminococcus, respectively.
But new data presented at the International Human Microbiome Congress in Paris yesterday suggest that the boundaries between the enterotypes may be fuzzier than the earlier work suggested.
Manimozhiyan Arumugam at the European Molecular Biology Laboratory in Heidelberg, Germany, an author on the original enterotype paper, revealed that the team has repeated the analysis with 663 Danish and Spanish adults, many more people than the original cohort of 39.
The results, as yet unpublished, show that a genus of archaea called Methanobrevibacter joins Ruminococcus as a defining microbe in the third enterotype. And the separation between this cluster and the Bacteroides-led enterotype is no longer as clear, although these two groups remain distinct from the Prevotella-driven one.