title: Characterization of galactooligosaccharides derived from lactulose.
abstract: Galactooligosaccharides are non-digestible carbohydrates with potential ability to modulate selectively the intestinal microbiota. In this work, a detailed characterization of oligosaccharides obtained by transgalactosylation reactions of the prebiotic lactulose, by using β-galactosidases of different fungal origin (Aspergillus oryzae, Aspergillus aculeatus and Kluveromyces lactis), is reported. Oligosaccharides of degree of polymerization (DP) up to 6 were detected and quantified by HPLC-ESI MS from a complex mixture produced by transgalactosylation reaction with A. oryzae (GOSLuAo), whereas only carbohydrates up to DP4 and DP5 were found for those obtained from the reaction with β-galactosidases from K. lactis (GOSLuKl) and A. aculeatus (GOSLuAa), respectively. Disaccharides (galactosyl-galactoses and galactosyl-fructoses) and trisaccharides were characterised in the three mixtures by GC-MS as their trimethylsilyl oximes. Galactosyl- and digalactosyl-glycerols were produced during the transgalactosylation reaction of lactulose with β-galactosidases from A. aculeatus and K. lactis, due to the presence of glycerol as enzyme stabiliser.
authors.affiliation: Instituto de Química Orgánica General (CSIC) C/Juan de la Cierva 3, 28006 Madrid, Spain.
authors.forename: Oswaldo
authors.initials: O
authors.lastname: Hernández-Hernández
authors.forename: Fernando
authors.initials: F
authors.lastname: Montañés
authors.forename: Alfonso
authors.initials: A
authors.lastname: Clemente
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Moreno
authors.forename: M Luz
authors.initials: ML
authors.lastname: Sanz
mesh_terms: D001230:Aspergillus / Q000201:enzymology; D002851:Chromatography, High Pressure Liquid; D004187:Disaccharides / Q000032:analysis / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D005690:Galactose / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D005990:Glycerol; D007716:Kluyveromyces / Q000201:enzymology; D007792:Lactulose / Q000737:chemistry* / Q000378:metabolism; D009844:Oligosaccharides / Q000032:analysis* / Q000737:chemistry; D056692:Prebiotics; D014312:Trisaccharides / Q000032:analysis / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D004187:Disaccharides; D005656:Fungal Proteins; D009844:Oligosaccharides; D056692:Prebiotics; D014312:Trisaccharides; D007792:Lactulose; D001616:beta-Galactosidase; D005990:Glycerol; D005690:Galactose