title: Homodimeric β-galactosidase from Lactobacillus delbrueckii subsp. bulgaricus DSM 20081: expression in Lactobacillus plantarum and biochemical characterization.
abstract: The lacZ gene from Lactobacillus delbrueckii subsp. bulgaricus DSM 20081, encoding a β-galactosidase of the glycoside hydrolase family GH2, was cloned into different inducible lactobacillal expression vectors for overexpression in the host strain Lactobacillus plantarum WCFS1. High expression levels were obtained in laboratory cultivations with yields of approximately 53000 U of β-galactosidase activity per liter of medium, which corresponds to ~170 mg of recombinant protein per liter and β-galactosidase levels amounting to 63% of the total intracellular protein of the host organism. The wild-type (nontagged) and histidine-tagged recombinant enzymes were purified to electrophoretic homogeneity and further characterized. β-Galactosidase from L. bulgaricus was used for lactose conversion and showed very high transgalactosylation activity. The maximum yield of galacto-oligosaccharides (GalOS) was approximately 50% when using an initial concentration of 600 mM lactose, indicating that the enzyme can be of interest for the production of GalOS.
authors.affiliation: School of Biotechnology and Food Technology, Hanoi University of Science and Technology, Hanoi, Vietnam.
authors.forename: Tien-Thanh
authors.initials: TT
authors.lastname: Nguyen
authors.forename: Hoang Anh
authors.initials: HA
authors.lastname: Nguyen
authors.forename: Sheryl Lozel
authors.initials: SL
authors.lastname: Arreola
authors.forename: Georg
authors.initials: G
authors.lastname: Mlynek
authors.forename: Kristina
authors.initials: K
authors.lastname: Djinović-Carugo
authors.forename: Geir
authors.initials: G
authors.lastname: Mathiesen
authors.forename: Thu-Ha
authors.initials: TH
authors.lastname: Nguyen
authors.forename: Dietmar
authors.initials: D
authors.lastname: Haltrich
mesh_terms: D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D005690:Galactose / Q000378:metabolism; D015870:Gene Expression; D005822:Genetic Vectors; D048668:Lactobacillus delbrueckii / Q000201:enzymology* / Q000235:genetics; D048191:Lactiplantibacillus plantarum / Q000201:enzymology* / Q000235:genetics; D007785:Lactose / Q000378:metabolism; D055503:Protein Multimerization; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D011994:Recombinant Proteins; D001616:beta-Galactosidase; D007785:Lactose; D005690:Galactose