Nondigestible Fructans Alter Gastrointestinal Barrier Function, Gene Expression, Histomorphology, and the Microbiota Profiles of Diet-Induced Obese C57BL/6J Mice.

BACKGROUND: Obesity is associated with compromised intestinal barrier function and shifts in gastrointestinal microbiota that may contribute to inflammation. Fiber provides benefits, but impacts of fiber type are not understood. OBJECTIVE: We aimed to determine the impact of cellulose compared with fructans on the fecal microbiota and gastrointestinal physiology in obese mice. METHODS: Eighteen-wk-old male diet-induced obese C57BL/6J mice (n = 6/group; 40.5 g) were fed high-fat diets (45% kcal fat) containing 5% cellulose (control), 10% cellulose, 10% short-chain fructooligosaccharides (scFOS), or 10% inulin for 4 wk. Cecal and colon tissues were collected to assess barrier function, histomorphology, and gene expression. Fecal DNA extracts were subjected to 16S ribosomal RNA amplicon-based Illumina MiSeq sequencing to assess microbiota. RESULTS: Body weight gain was greater (P < 0.05) in scFOS-fed than in 10% cellulose-fed mice. Both groups of fructan-fed mice had greater (P < 0.05) cecal crypt depth (scFOS: 141 µm; inulin: 145 µm) than both groups of cellulose-fed mice (5% and 10%: 109 µm). Inulin-fed mice had greater (P < 0.05) cecal transmural resistance (101 Ω × cm(2)) than 5% cellulose-fed controls (45 Ω × cm(2)). Inulin-fed mice had lower (P < 0.05) colonic mRNA abundance of Ocln (0.41) and Mct1 (0.35) than those fed 10% cellulose (Ocln: 1.28; Mct1: 0.90). Fructan and cellulose groups had different UniFrac distances of fecal microbiota (P < 0.05) and α diversity, which demonstrated lower (P < 0.01) species richness in fructan-fed mice. Mice fed scFOS had greater (P < 0.05) Actinobacteria (15.9%) and Verrucomicrobia (Akkermansia) (17.0%) than 5% controls (Actinobacteria: 0.07%; Akkermansia: 0.08%). Relative abundance of Akkermansia was positively correlated (r = 0.56, P < 0.01) with cecal crypt depth. CONCLUSIONS: Fructans markedly shifted gut microbiota and improved intestinal physiology in obese mice, but the mechanisms by which they affect gut integrity and inflammation in the obese are still unknown.

Comparative analysis of salivary bacterial microbiome diversity in edentulous infants and their mothers or primary care givers using pyrosequencing.

Bacterial contribution to oral disease has been studied in young children, but there is a lack of data addressing the developmental perspective in edentulous infants. Our primary objectives were to use pyrosequencing to phylogenetically characterize the salivary bacterial microbiome of edentulous infants and to make comparisons against their mothers. Saliva samples were collected from 5 edentulous infants (mean age = 4.6±1.2 mo old) and their mothers or primary care givers (mean age = 30.8±9.5 y old). Salivary DNA was extracted, used to generate DNA amplicons of the V4-V6 hypervariable region of the bacterial 16S rDNA gene, and subjected to 454-pyrosequencing. On average, over 80,000 sequences per sample were generated. High bacterial diversity was noted in the saliva of adults [1012 operational taxonomical units (OTU) at 3% divergence] and infants (578 OTU at 3% divergence). Firmicutes, Proteobacteria, Actinobacteria, and Fusobacteria were predominant bacterial phyla present in all samples. A total of 397 bacterial genera were present in our dataset. Of the 28 genera different (P<0.05) between infants and adults, 27 had a greater prevalence in adults. The exception was Streptococcus, which was the predominant genera in infant saliva (62.2% in infants vs. 20.4% in adults; P<0.05). Veillonella, Neisseria, Rothia, Haemophilus, Gemella, Granulicatella, Leptotrichia, and Fusobacterium were also predominant genera in infant samples, while Haemophilus, Neisseria, Veillonella, Fusobacterium, Oribacterium, Rothia, Treponema, and Actinomyces were predominant in adults. Our data demonstrate that although the adult saliva bacterial microbiome had a greater OTU count than infants, a rich bacterial community exists in the infant oral cavity prior to tooth eruption. Streptococcus, Veillonella, and Neisseria are the predominant bacterial genera present in infants. Further research is required to characterize the development of oral microbiota early in life and identify environmental factors that impact colonization and oral and gastrointestinal disease risk.