The Gut Microbiota
Human individuals can harbor over 150 different microbial species in their gut, which collectively encode more than 100-fold more non-redundant genes than there are in the human genome.[16,24] More recent data, however, has challenged this number, suggesting that the ratio between bacteria and human cells is closer to 1:1.[25] In healthy humans, the intestinal microbiota consists of members of all three domains of life: bacteria, archaea and eukarya, of which the bacterial community is the most abundant and diverse.[8] Nine different bacterial phyla have been recorded in humans so far, of which the bacteroidetes and firmicutes dominate.[8,16,24] Many of these bacteria in the gut have not been cultivated. Recent breakthroughs in the successful culture of the previously 'unculturable' human microbiota have revealed a whole spectrum of novel bacterial species and taxa.[26] The application of novel sequencing techniques provides an opportunity to understand this complex ecosystem much better.[8,13]
The intestinal microbiota plays a critical role in priming the host's immune system, gut maturation and gut functions, such as nutrient uptake and metabolism, mucosal barrier function, enteric nervous system and motility.[27–29] Numerous host genes seem to be specifically altered in response to various members of the microbiota, showing the importance of the microbial composition to the body's response.[30,31]
Crit Care. 2018;22(78) © 2018 BioMed Central, Ltd.
Copyright to this article is held by the author(s), licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original citation.
Comments