Diets Enriched in Oat Bran or Wheat Bran Temporally and Differentially Alter the Composition of the Fecal Community of Rats

Abstract

A clear understanding of how diet alters gastrointestinal communities is important given the suggested link between gut community composition and a wide variety of disease pathologies. To characterize this link for commonly consumed dietary fiber sources, we investigated the change in the fecal community of rats fed diets containing 5% nonnutritive fiber (control), 3% (wt:wt) oat bran plus 2% nonnutritive fiber (OB), or 5% (w/w) wheat bran (WB) over a 28-d feeding trial using both molecular- and cultivation-based methodologies. Pooled fecal samples from 8 rats fed the same diet were analyzed at 4 time points. On d 28, bran-fed rats had approximately twice the total cultivable bacteria than rats fed the control diet. Over the course of feeding, the cultivable community was initially dominated by bacteroides, then by bifidobacteria, lactobacilli, enterococci, and various enterics. In contrast, molecular analysis revealed the appearance of new operational taxonomic units (phylotypes) that were both temporally and inequitably distributed throughout the fecal community. The majority of change occurred in 2 major lineages within the Firmicutes: the Clostridium coccoides group and the Clostridium leptum subgroup. The time course of change depended on the source of bran, with the majority of new phylotypes appearing by d 14 (OB) or d 28 (WB), although adaptation of the fecal community was slow and continued over the entire feeding trial. Bacterial community richness was higher in bran-fed rats than in those fed the control diet. Change within the C. coccoides and C. leptum lineages likely reflect their high abundance within the gut bacterial community and the role of clostridia in fiber digestion. The results illustrate the limitations of relying solely on cultivation to assess bacterial changes and illustrate that community changes are complex in an ecosystem containing high numbers of interdependent and competing species of bacteria.

Antimicrobial activity of bacteriocin-producing lactic acid bacteria isolated from cheeses and yogurts

“…Near full-length 16S rRNA gene sequencing was used to identify unknown bacteriocin producing LAB strains based on the method of Abnous et al ([2009]). Briefly, genomic DNA was extracted from isolates using the UltraClean TM Microbial DNA Isolation kit (MO Bio laboratories, Inc., Carlsbas, CA, USA).…”

“…Briefly, genomic DNA was extracted from isolates using the UltraClean TM Microbial DNA Isolation kit (MO Bio laboratories, Inc., Carlsbas, CA, USA). Universal primers F44 (5’RGTTYGATYMTGGCTCAG-3’) and R1543 (5’-GNNTACCTTKTTACG ACTT-3’) (Abnous et al, [2009]) were used for the amplification of the 16S rRNA gene by PCR. PCR reactions were carried out using a Biometra thermal cycler (Montreal Biotech Inc., Kirkland, QC, Canada) with the following cycle parameters: an initial denaturation at 94°C for 2 min, followed by 35 cycles of denaturation at 94°C for 30 s, annealing at 52°C for 30 s, and elongation at 72°C for 1 min.…”

Spaceflight Influences both Mucosal and Peripheral Cytokine Production in PTN-Tg and Wild Type Mice

“…DNA was recovered from each sample by first grinding in liquid nitrogen then purified using the QIAamp DNA stool mini kit (Qiagen Inc, Mississauga, ON). Bacterial tag-encoded FLX amplicon pyrosequencing was performed as previously described [52] using the forward primer F44 [53] and the reverse primer R519 [54]. Initial sequence processing was carried out using Esprit [55].…”

Obesity-associated cancer risk: the role of intestinal microbiota in the etiology of the host proinflammatory state

“…Further, LPS exposure induced cyclooxygenases and production of PGE2 both in vitro and in vivo (131, 132). Conversely, high fiber diets are expected to reduce LPS exposures via alteration of microbial composition, improvement in the mucosal barrier function through facilitating tight junction assembly and reduction in epithelial permeability through production of short chain fatty acids (133–136). Likewise, dietary antioxidants can counteract the adverse effects of LPS exposure in colon smooth muscle cells (137).…”