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Objective: Contrary to the long-standing prerequisite of inducing selective (ie, bifidogenic) effects, recent findings suggest that prebiotic interventions lead to ecosystem-wide microbiota shifts. Yet, a comprehensive characterisation of this process is still lacking. Here, we apply 16S rDNA microbiota profiling and matching (gas chromatography mass spectrometry) metabolomics to assess the consequences of inulin fermentation both on the composition of the colon bacterial ecosystem and faecal metabolites profiles., Design: Faecal samples collected during a double-blind, randomised, cross-over intervention study set up to assess the effect of inulin consumption on stool frequency in healthy adults with mild constipation were analysed. Faecal microbiota composition and metabolite profiles were linked to the study's clinical outcome as well as to quality-of-life measurements recorded., Results: While faecal metabolite profiles were not significantly altered by inulin consumption, our analyses did detect a modest effect on global microbiota composition and specific inulin-induced changes in relative abundances of Anaerostipes , Bilophila and Bifidobacterium were identified. The observed decrease in Bilophila abundances following inulin consumption was associated with both softer stools and a favourable change in constipation-specific quality-of-life measures., Conclusions: Ecosystem-wide analysis of the effect of a dietary intervention with prebiotic inulin-type fructans on the colon microbiota revealed that this effect is specifically associated with three genera, one of which ( Bilophila ) representing a promising novel target for mechanistic research., Trial Registration Number: NCT02548247., Competing Interests: Competing interests: MS and ST are employees of BENEO/Südzucker Group. The authors alone are responsible for the content and writing of this article., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

Scope: Health benefits of prebiotic administration have been judged mainly from the increased numbers of bifidobacteria and the enhanced production of short-chain fatty acids in the colon. Only a few studies have focused on the capacity of prebiotics to decrease the proteolytic fermentation, which might contribute to health as well., Methods and Results: The influence of the prebiotic oligofructose-enriched inulin (OF-IN) on the pattern of volatile organic compounds was characterized using an in vitro faecal model. Faecal slurries, obtained from healthy subjects, were anaerobically incubated at 37 °C with and without different doses of OF-IN (2.5, 5, 10, or 20 mg) and changes in the metabolite pattern and pH were evaluated. A total of 107 different volatile organic compounds were identified and classified according to their chemical classes. The concentration of esters and acids significantly increased with increasing doses of OF-IN. Similar effects were observed for some aldehydes. To the contrary, OF-IN dose-dependently inhibited the formation of S-compounds. Also, the generation of other protein fermentation metabolites such as phenolic compounds was inhibited in the presence of OF-IN., Conclusion: Our results confirmed a clear dose-dependent stimulation of saccharolytic fermentation. Importantly, a significant decrease in toxic protein fermentation metabolites such as sulphides attended these effects., (Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Wheat bran fibers are considered beneficial to human health through their impact on gut microbiota composition and activity. Here, we assessed the prebiotic potential of selected bran fractions by performing a series of fecal slurry anaerobic fermentation experiments using aleurone as well as total, ultrafine, and soluble wheat bran (swb) as carbon sources. By combining amplicon-based community profiling with a fluorescent in situ hybridization (FISH) approach, we found that incubation conditions favor the growth of Proteobacteria such as Escherichia and Bilophila. These effects were countered in all but one [total wheat bran (twb)] fermentation experiments. Growth of Bifidobacterium species was stimulated after fermentation using ultrafine, soluble, and twb, in the latter two as part of a general increase in bacterial load. Both ultrafine and swb fermentation resulted in a trade-off between Bifidobacterium and Bilophila, as previously observed in human dietary supplementation studies looking at the effect of inulin-type fructans on the human gut microbiota. Aleurone selectively stimulated growth of Dorea and butyrateproducing Roseburia. All fermentation experiments induced enhanced gas production; increased butyrate concentrations were only observed following soluble bran incubation. Our results open perspectives for the development of aleurone as a complementary prebiotic selectively targeting colon butyrate producers. [ABSTRACT FROM AUTHOR]

Kinetic analyses of bacterial growth, carbohydrate consumption, and metabolite production of five butyrate- producing clostridial cluster XIVa colon bacteria grown on acetate plus fructose, oligofructose, inulin, or lactate were performed. A gas chromatography method was set up to assess H2 and CO2 production online and to ensure complete coverage of all metabolites produced. Method accuracy was confirmed through the calculation of electron and carbon recoveries. Fermentations with Anaerostipes caccae DSM 14662T, Roseburia faecis DSM 16840T, Roseburia hominis DSM 16839T, and Roseburia intestinalis DSM 14610T revealed similar patterns of metabolite production with butyrate, CO2, and H2 as the main metabolites. R. faecis DSM 16840T and R. intestinalis DSM 14610T were able to degrade oligofructose, displaying a nonpreferential breakdown mechanism. Lactate consumption was only observed with A. caccae DSM 14662T. Roseburia inulinivorans DSM 16841T was the only strain included in the present study that was able to grow on fructose, oligofructose, and inulin. The metabolites produced were lactate, butyrate, and CO2, without H2 production, indicating an energy metabolism distinct from that of other Roseburia species. Oligofructose degradation was nonpreferential. In a coculture of R. inulinivorans DSM 16841T with the highly competitive strain Bifidobacterium longum subsp. longum LMG 11047 on inulin, hardly any production of butyrate and CO2 was detected, indicating a lack of competitiveness of the butyrate producer. Complete recovery of metabolites during fermentations of clostridial cluster XIVa butyrate-producing colon bacteria allowed stoichiometric balancing of the metabolic pathway for butyrate production, including H2 formation. [ABSTRACT FROM AUTHOR]

Kinetic analyses of bacterial growth, carbohydrate consumption, and metabolite production of 18 Bifidobacterium strains grown on fructose, oligofructose, or inulin were performed. A principal component analysis of the data sets, expanded with the results of a genetic screen concerning the presence of a β-fructofuranosidase gene previously encountered in Bifidobacterium animalis subsp. lactis DSM 10140T, revealed the existence of four clusters among the bifidobacteria tested. Strains belonging to a first cluster could not degrade oligofructose or inulin. Strains in a second cluster could degrade oligofructose, displaying a preferential breakdown mechanism, but did not grow on inulin. Fructose consumption was faster than oligofructose degradation. A third cluster was composed of strains that degraded all oligofructose fractions simultaneously and could partially break down inulin. Oligofructose degradation was substantially faster than fructose consumption. A fourth, smaller cluster consisted of strains that shared high fructose consumption and oligofructose degradation rates and were able to perform partial breakdown of inulin. For all strains, a metabolic shift toward more acetate, formate, and ethanol production, at the expense of lactate production, was observed during growth on less readily fermentable energy sources. No correlation between breakdown patterns and the presence of the f3-fructofuranosidase gene could be detected. These variations indicate niche-specific adaptation of bifidobacteria and could have in vivo implications on the strain specificity of the stimulatory effect of inulin-type fructans on bifidobacteria. [ABSTRACT FROM AUTHOR]