Article The Rockefeller University Press $30.00

Complex microbial populations inhabit the mam-malian gastrointestinal tract and are referred to as the microbiota. Next generation DNA sequenc-ing platforms have been used to sequence 16S ribosomal RNA (rRNA) genes amplified from complex bacterial populations and have enabled investigation of the gut microbiota, revealing that thousands of different bacterial species contribute to the commensal community (Dethlefsen and Relman, 2011). Most of the bacterial taxa in the gut belong to the Firmicutes and Bacteroidetes phyla, whereas bacteria belonging to the Proteo-bacteria, Actinobacteria, Verrucomicrobia, or Fuso-bacteria phyla form minority populations (Eckburg et al., 2005). The bacterial communities inhabit-ing the small and large intestine are distinct (Garner et al., 2009). Furthermore, microbial populations in close proximity to the intestinal epithelium differ from those inhabiting the intestinal lumen (Hill et al., 2010). The intestinal microbiota provides many benefits for its host. Intestinal bacteria contrib-ute to the gut’s primary function of absorbing nutrients by producing enzymes that break down otherwise indigestible compounds (Hooper et al., 2002). Intestinal bacteria also contribute to the development of the immune system (Hill and Artis, 2010) and enhance resistance against infection by patho-genic bacteria (Vollaard and Clasener, 1994). The intestinal microbiota promotes angiogen-esis in the intestine (Stappenbeck et al., 2002) and provides protection against intestinal epithelial injury (Rakoff-Nahoum et al., 2004). Changes in the composition of the microbiot