title: Structural identification of novel oligosaccharides produced by Lactobacillus bulgaricus and Lactobacillus plantarum.
abstract: β-Galactosidases (β-Gal) of lactic acid bacteria produce oligosaccharides from lactose when suitable acceptor carbohydrates are present. This study aimed to elucidate the structure of oligosaccharides formed by galactosylation of N-acetylglucosamine (GlcNAc) and fucose. Crude cellular extract of  Lactobacillus bulgaricus  and LacLM of  Lactobacillus plantarum  were used as sources of β-Gal activity. Disaccharides obtained by galactosylation of GlcNAc were identified as Gal-β-(1→4)-GlcNAc or Gal-β-(1→6)-GlcNAc by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and comparison with external standards. Trisaccharides were identified as Gal-β-(1→6)-Gal-β-(1→[4 or 6])-GlcNAc by LC-MS, analysis of the MS/MS spectra of selected in-source fragment ions, and their relative retention times. LC-MS analysis revealed the presence of five galactosylated fucosides, but their linkage type could not be identified, partly due to the lack of reference compounds. β-Gal of lactic acid bacteria may serve as suitable tools for the chemoenzymatic synthesis of therapeutic oligosaccharides.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, 410 Agriculture/Forestry Centre, Edmonton, Alberta T6E 2P5, Canada.
authors.forename: Brenna A
authors.initials: BA
authors.lastname: Black
authors.forename: Vivian S Y
authors.initials: VS
authors.lastname: Lee
authors.forename: Yuan Yuan
authors.initials: YY
authors.lastname: Zhao
authors.forename: Ying
authors.initials: Y
authors.lastname: Hu
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Curtis
authors.forename: Michael G
authors.initials: MG
authors.lastname: Gänzle
mesh_terms: D002240:Carbohydrate Sequence; D007778:Lactobacillus / Q000737:chemistry / Q000378:metabolism*; D048191:Lactiplantibacillus plantarum / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D009844:Oligosaccharides