title: Evaluation of oligosaccharide synthesis from lactose and lactulose using β-galactosidases from Kluyveromyces isolated from artisanal cheeses.
abstract: The β-galactosidase activity of 15  Kluyveromyces  strains isolated from cheese belonging to  Kluyveromyces lactis  and  Kluyveromyces marxianus  species was tested for the production of oligosaccharides derived from lactose (GOS) and lactulose (OsLu). All  Kluyveromyces  crude cell extracts (CEEs) produced GOS, such as 6-galactobiose and 3'-, 4'-, and 6'-galactosyl-lactose. At 4 h of reaction, the main trisaccharide formed was 6'-galactosyl-lactose (20 g/100 g of total carbohydrates). The formation of OsLu was also observed by all CEEs tested, with 6-galactobiose, 6'-galactosyl-lactulose, and 1-galactosyl-lactulose being found in all of the reaction mixtures. The synthesis of trisaccharides predominated over other oligosaccharides.  K. marxianus  strain O3 produced the highest yields of GOS and OsLu after 4 h of reaction, reaching 42 g/100 g of total carbohydrates (corresponding to 80% lactose hydrolysis) and 45 g/100 g of total carbohydrates (corresponding to 87% lactulose hydrolysis), respectively. Therefore, the present study contributes to a better insight into dairy  Kluyveromyces  β-galactosidases and shows the feasibility of these enzymes to transglycosylate lactose and lactulose, producing high yields of prebiotic oligosaccharides.
authors.affiliation: Departamento de Biotecnología de Alimentos, Instituto de Agroquímica y Tecnología de Alimentos,  Consejo Superior de Investigaciones Científicas (CSIC) , Avenida Agustín Escardino 7, 46980 Paterna, Valencia, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Padilla
authors.forename: Ana I
authors.initials: AI
authors.lastname: Ruiz-Matute
authors.forename: Carmela
authors.initials: C
authors.lastname: Belloch
authors.forename: Alejandra
authors.initials: A
authors.lastname: Cardelle-Cobas
authors.forename: Nieves
authors.initials: N
authors.lastname: Corzo
authors.forename: Paloma
authors.initials: P
authors.lastname: Manzanares
mesh_terms: D002611:Cheese / Q000382:microbiology*; D007716:Kluyveromyces / Q000201:enzymology* / Q000302:isolation & purification; D007785:Lactose / Q000378:metabolism*; D007792:Lactulose / Q000378:metabolism*; D009844:Oligosaccharides / Q000096:biosynthesis*; D056692:Prebiotics; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D009844:Oligosaccharides; D056692:Prebiotics; D007792:Lactulose; D001616:beta-Galactosidase; D007785:Lactose