Galacto-oligosaccharide synthesis from lactose solution or skim milk using the β-galactosidase from Bacillus circulans.
The synthesis of galacto-oligosaccharides (GOS) catalyzed by a novel commercial preparation of β-galactosidase from  Bacillus circulans  (Biolactase) was studied, and the products were characterized by MS and NMR. Using 400 g/L lactose and 1.5 enzyme units per milliliter, the maximum GOS yield, measured by HPAEC-PAD analysis, was 165 g/L (41% w/w of total carbohydrates in the mixture). The major transgalactosylation products were the trisaccharide Gal-β(1→4)-Gal-β(1→4)-Glc and the tetrasaccharide Gal-β(1→4)-Gal-β(1→4)-Gal-β(1→4)-Glc. The GOS yield increased to 198 g/L (49.4% w/w of total carbohydrates) using a higher enzyme concentration (15 U/mL), which minimized the enzyme inactivation under reaction conditions. Using skim milk (with a lactose concentration of 46 g/L), the enzyme also displayed transgalactosylation activity: maximum GOS yield accounted for 15.4% (7.1 g/L), which was obtained at 50% lactose conversion.
Instituto de Catálisis y Petroleoquímica,  CSIC , 28049 Madrid, Spain.
Barbara
B
Rodriguez-Colinas
Ana
A
Poveda
Jesus
J
Jimenez-Barbero
Antonio O
AO
Ballesteros
Francisco J
FJ
Plou
D000818:Animals; D001407:Bacillus / Q000201:enzymology*; D002240:Carbohydrate Sequence; D002417:Cattle; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry*; D007700:Kinetics; D007785:Lactose / Q000737:chemistry*; D008892:Milk / Q000737:chemistry*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D013696:Temperature; D001616:beta-Galactosidase / Q000737:chemistry*
D005656:Fungal Proteins; D009844:Oligosaccharides; D001616:beta-Galactosidase; D007785:Lactose