title: Analysis of fermentation selectivity of purified galacto-oligosaccharides by in vitro human faecal fermentation.
abstract: The in vitro fermentation of several purified galacto-oligosaccharides (GOS), specifically the trisaccharides 4'-galactosyl-lactose and 6'-galactosyl-lactose and a mixture of the disaccharides 6-galactobiose and allolactose, was carried out. The bifidogenic effect of GOS at 1% (w/v) was studied in a pH-controlled batch culture fermentation system inoculated with healthy adult human faeces. Results were compared with those obtained with a commercial GOS mixture (Bimuno-GOS). Changes in bacterial populations measured through fluorescence in situ hybridization and short-chain fatty acid (SCFA) production were determined. Bifidobacteria increased after 10-h fermentation for all the GOS substrates, but the changes were only statistically significant (P<0.05) for the mixture of disaccharides and Bimuno-GOS. Acetic acid, whose formation is consistent with bifidobacteria metabolism, was the major SCFA synthesized. The acetate concentration at 10 h was similar with all the substrates (45-50 mM) and significantly higher than the observed for formic, propionic and butyric acids. All the purified GOS could be considered bifidogenic under the assayed conditions, displaying a selectivity index in the range 2.1-3.0, which was slightly lower than the determined for the commercial mixture Bimuno-GOS.
authors.affiliation: Instituto de Catalisis y Petroleoquimica, CSIC, 28049 Madrid, Spain.
authors.forename: Barbara
authors.initials: B
authors.lastname: Rodriguez-Colinas
authors.forename: Sofia
authors.initials: S
authors.lastname: Kolida
authors.forename: Magdalena
authors.initials: M
authors.lastname: Baran
authors.forename: Antonio O
authors.initials: AO
authors.lastname: Ballesteros
authors.forename: Robert A
authors.initials: RA
authors.lastname: Rastall
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Plou
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D058448:Biota; D005232:Fatty Acids, Volatile / Q000032:analysis; D005243:Feces / Q000382:microbiology*; D005285:Fermentation; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D014312:Trisaccharides / Q000378:metabolism*
chemical_list: D005232:Fatty Acids, Volatile; D014312:Trisaccharides