title: Arabinoxylan oligosaccharide hydrolysis by family 43 and 51 glycosidases from Lactobacillus brevis DSM 20054.
abstract: Due to their potential prebiotic properties, arabinoxylan-derived oligosaccharides [(A)XOS] are of great interest as functional food and feed ingredients. While the (A)XOS metabolism of Bifidobacteriaceae has been extensively studied, information regarding lactic acid bacteria (LAB) is still limited in this context. The aim of the present study was to fill this important gap by characterizing candidate (A)XOS hydrolyzing glycoside hydrolases (GHs) identified in the genome of Lactobacillus brevis DSM 20054. Two putative GH family 43 xylosidases (XynB1 and XynB2) and a GH family 43 arabinofuranosidase (Abf3) were heterologously expressed and characterized. While the function of XynB1 remains unclear, XynB2 could efficiently hydrolyze xylooligosaccharides. Abf3 displayed high specific activity for arabinobiose but could not release arabinose from an (A)XOS preparation. However, two previously reported GH 51 arabinofuranosidases from Lb. brevis were able to specifically remove α-1,3-linked arabinofuranosyl residues from arabino-xylooligosaccharides (AXHm3 specificity). These results imply that Lb. brevis is at least genetically equipped with functional enzymes in order to hydrolyze the depolymerization products of (arabino)xylans and arabinans. The distribution of related genes in Lactobacillales genomes indicates that GH 43 and, especially, GH 51 glycosidase genes are rare among LAB and mainly occur in obligately heterofermentative Lactobacillus spp., Pediococcus spp., members of the Leuconostoc/Weissella branch, and Enterococcus spp. Apart from the prebiotic viewpoint, this information also adds new perspectives on the carbohydrate (i.e., pentose-oligomer) metabolism of LAB species involved in the fermentation of hemicellulose-containing substrates.
authors.affiliation: Department of Food Science and Technology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria.
authors.forename: Herbert
authors.initials: H
authors.lastname: Michlmayr
authors.forename: Johannes
authors.initials: J
authors.lastname: Hell
authors.forename: Cindy
authors.initials: C
authors.lastname: Lorenz
authors.forename: Stefan
authors.initials: S
authors.lastname: Böhmdorfer
authors.forename: Thomas
authors.initials: T
authors.lastname: Rosenau
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kneifel
mesh_terms: D001483:Base Sequence; D002849:Chromatography, Gas; D002852:Chromatography, Ion Exchange; D017931:DNA Primers / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D052196:Levilactobacillus brevis / Q000201:enzymology*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012394:Rosaniline Dyes; D017422:Sequence Analysis, DNA; D014990:Xylans / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D009844:Oligosaccharides; D012394:Rosaniline Dyes; D014990:Xylans; C048139:Coomassie blue; C085118:arabinoxylan; D006026:Glycoside Hydrolases