title: Detailed analysis of galactooligosaccharides synthesis with β-galactosidase from Aspergillus oryzae.
abstract: The synthesis of galactooligosaccharides (GOS) catalyzed by β-galactosidase from Aspergillus oryzae (Enzeco) was studied. Using 400 g/L of lactose and 15 U/mL, maximum GOS yield, measured by HPAEC-PAD, was 26.8% w/w of total carbohydrates, obtained at approximately 70% lactose conversion. No less than 17 carbohydrates were identified; the major transgalactosylation product was 6'-O-β-galactosyl-lactose, representing nearly one-third (in weight) of total GOS. In contrast with previous reports, the presence of at least five disaccharides was detected, which accounted for 40% of the total GOS at the point of maximum GOS concentration (allolactose and 6-galactobiose were the major products). A. oryzae β-galactosidase showed a preference to form β(1→6) bonds, followed by β(1→3) and β(1→4) linkages. Results were compared with those obtained with β-galactosidases from Kluyveromyces lactis and Bacillus circulans. The highest GOS yield and specific productivity were achieved with B. circulans β-galactosidase. The specificity of the linkages formed and distribution of di-, tri-, and higher GOS varied significantly among the three β-galactosidases.
authors: Instituto de Catálisis y Petroleoquímica, CSIC, 28049 Madrid, Spain.
authors: Paulina
authors: P
authors: Urrutia
authors: Bárbara
authors: B
authors: Rodriguez-Colinas
authors: Lucía
authors: L
authors: Fernandez-Arrojo
authors: Antonio O
authors: AO
authors: Ballesteros
authors: Lorena
authors: L
authors: Wilson
authors: Andrés
authors: A
authors: Illanes
authors: Francisco J
authors: FJ
authors: Plou
mesh_terms: D001236:Aspergillus oryzae / Q000201:enzymology*; D001407:Bacillus / Q000201:enzymology; D004187:Disaccharides / Q000096:biosynthesis; D006863:Hydrogen-Ion Concentration; D007716:Kluyveromyces / Q000201:enzymology; D007785:Lactose / Q000096:biosynthesis; D009682:Magnetic Resonance Spectroscopy; D013696:Temperature; D014312:Trisaccharides / Q000096:biosynthesis*; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D004187:Disaccharides; D014312:Trisaccharides; C056853:6-O-galactopyranosylgalactose; C001970:allolactose; D001616:beta-Galactosidase; D007785:Lactose