An enterotype is a classification of living organisms based on its bacteriological ecosystem

Ecosystem

An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

 in the human gut microbiome

Microbiome

A microbiome is the totality of microbes, their genetic elements , and environmental interactions in a defined environment. A defined environment could, for example, be the gut of a human being or a soil sample. Thus, microbiome usually includes microbiota and their complete genetic elements...

. The discovery of three human enterotypes was announced in the April 2011 issue of Nature

Nature (journal)

Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...

by Peer Bork

Peer Bork

Doctor Peer Bork, PhD, is senior group leader and joint head of theStructural and Computational Biology unit at EMBL, a Europeanresearch organization with headquarters in Heidelberg. He also holds...

 and his associates.

Type 1 is characterized by high levels of Bacteroides

Bacteroides

Bacteroides is a genus of Gram-negative, bacillus bacteria. Bacteroides species are non-endospore-forming, anaerobes, and may be either motile or non-motile, depending on the species. The DNA base composition is 40-48% GC. Unusual in bacterial organisms, Bacteroides membranes contain sphingolipids...

 while type 2 has few Bacteroides but Prevotella

Prevotella

Prevotella is a genus of bacteria.Bacteroides melaninogenicus has recently been reclassified and split into Prevotella melaninogenica and Prevotella intermedia....

 are common, and type 3 has high levels of Ruminococcus

Ruminococcus

Ruminococcus is a genus of bacteria in the class Clostridia. They are anaerobic, gram-positive gut microbes. One or more species in this genus are found in significant numbers in the intestines of humans. The type species is R. flavefaciens...

.