title: Human gut microbiota in obesity and after gastric bypass.
abstract: Recent evidence suggests that the microbial community in the human intestine may play an important role in the pathogenesis of obesity. We examined 184,094 sequences of microbial 16S rRNA genes from PCR amplicons by using the 454 pyrosequencing technology to compare the microbial community structures of 9 individuals, 3 in each of the categories of normal weight, morbidly obese, and post-gastric-bypass surgery. Phylogenetic analysis demonstrated that although the Bacteria in the human intestinal community were highly diverse, they fell mainly into 6 bacterial divisions that had distinct differences in the 3 study groups. Specifically, Firmicutes were dominant in normal-weight and obese individuals but significantly decreased in post-gastric-bypass individuals, who had a proportional increase of Gammaproteobacteria. Numbers of the H(2)-producing Prevotellaceae were highly enriched in the obese individuals. Unlike the highly diverse Bacteria, the Archaea comprised mainly members of the order Methanobacteriales, which are H(2)-oxidizing methanogens. Using real-time PCR, we detected significantly higher numbers of H(2)-utilizing methanogenic Archaea in obese individuals than in normal-weight or post-gastric-bypass individuals. The coexistence of H(2)-producing bacteria with relatively high numbers of H(2)-utilizing methanogenic Archaea in the gastrointestinal tract of obese individuals leads to the hypothesis that interspecies H(2) transfer between bacterial and archaeal species is an important mechanism for increasing energy uptake by the human large intestine in obese persons. The large bacterial population shift seen in the post-gastric-bypass individuals may reflect the double impact of the gut alteration caused by the surgical procedure and the consequent changes in food ingestion and digestion.
authors.affiliation: Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Husen
authors.initials: H
authors.lastname: Zhang
authors.forename: John K
authors.initials: JK
authors.lastname: DiBaise
authors.forename: Andrea
authors.initials: A
authors.lastname: Zuccolo
authors.forename: Dave
authors.initials: D
authors.lastname: Kudrna
authors.forename: Michele
authors.initials: M
authors.lastname: Braidotti
authors.forename: Yeisoo
authors.initials: Y
authors.lastname: Yu
authors.forename: Prathap
authors.initials: P
authors.lastname: Parameswaran
authors.forename: Michael D
authors.initials: MD
authors.lastname: Crowell
authors.forename: Rod
authors.initials: R
authors.lastname: Wing
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Rittmann
authors.forename: Rosa
authors.initials: R
authors.lastname: Krajmalnik-Brown
mesh_terms: D000328:Adult; D001105:Archaea / Q000378:metabolism; D015992:Body Mass Index; D005260:Female; D015390:Gastric Bypass / Q000009:adverse effects*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D008969:Molecular Sequence Data; D009765:Obesity / Q000382:microbiology / Q000473:pathology* / Q000601:surgery*; D011183:Postoperative Complications; D012336:RNA, Ribosomal, 16S / Q000737:chemistry; D017422:Sequence Analysis, DNA
chemical_list: D012336:RNA, Ribosomal, 16S