Fecal Microbiota Responses to Bran Particles Are Specific to Cereal Type and In Vitro Digestion Methods That Mimic Upper Gastrointestinal Tract Passage

Abstract

Although in vitro studies to identify interactions between food components and the colonic microbiota employ distinct methods to mimic upper gastrointestinal (GI) tract digestion, the effects of differences in protocols on fermentation have not been rigorously addressed. Here, we compared two widely used upper GI tract digestion methods on four different cereal brans in fermentations by fecal microbiota to test the hypotheses that (1) different methods are varyingly efficient in removing accessible starches and proteins from dietary components and (2) these result in cereal-specific differences in fermentation by fecal microbiota. Our results supported both hypotheses, in that the methods differed significantly in bran starch and protein retention and that the effects were cereal-specific. Furthermore, these differences impacted fermentation by the fecal microbiota of healthy donors, altering both short-chain fatty acid production and microbial community composition. These data suggest that digestion methods should be standardized across laboratories for in vitro fiber fermentation studies.

Bifidobacterium longum-fermented rice bran and rice bran supplementation affects the gut microbiome and metabolome

“…Many rice bran components have previously-reported roles in slowing tumour and pathogen growth via altering cell proliferation, combating oxidative stress, reducing inflammation and modulating the gut microbiome and metabolism (Fabian and Ju, 2011;Law et al, 2017;So et al, 2016;Sohail et al, 2017). Gut commensal microbes have shown the capacity for fermenting rice bran carbohydrates, phytochemicals, lipids and amino acids in animals and people (Sheflin et al, 2017;Tuncil et al, 2018).…”

Effect of protease supplementation on the digestibility of amino acids in animal-origin meals for broiler diets

“…The coefficients of true ileal digestibility of amino acids of the PVM, SVM and BMBM were higher than those found in the literature consulted (Scotta et al 2016;Rostagno et al 2017). These results demonstrate that the AOMs used in this experiment were adequately processed, with nearly complete hydrolysis, resulting in higher digestibility values of the amino acids (Tuncil et al 2018). Another factor was the use of the proteolytic enzyme, which improved the CTID of the majority of the amino acids.…”

Maize Bran Particle Size Governs the Community Composition and Metabolic Output of Human Gut Microbiota in in vitro Fermentations

“…We simulated passage through the upper gastrointestinal (GI) tract of the different sizes of maize bran particles obtained after milling and sieving through in vitro digestion as previously described (as Method A) (Yang et al, 2013). We chose this method for simulated digestion because we recently determined that this method is generally more effective at removal of starch content for maize (Tuncil et al, 2018a). During the upper GI digestion, the maize bran particles were treated with pepsin, pancreatin and amyloglucosidase for 30 min, 6 and 6 h respectively.…”

“…We analyzed neutral monosaccharides from different maize bran particle sizes post-upper GI tract digestion using gas chromatography on a capillary column (SP2330, Supelco, Bellefonte, PA, United States) coupled with mass spectroscopy (GC-MS; models 7890A gas chromatograph and 5975C inert mass selective detector, Agilent Technologies, Inc., Santa Clara, CA, United States) as described previously (Tuncil et al, 2018a). Helium was used as carrier gas.…”

“…The total starch contents were quantified spectrophotometrically using the total starch assay kit (K-TSTA; Megazyme International, Wicklow, Ireland), according to the manufacturer's instructions. Protein contents of the samples were determined by the Dumas method (N × 6.25) using a LECO TruMac nitrogen analyzer (LECO Corporation, St. Joseph, MI, United States) (Tuncil et al, 2018a).…”