Production of Prebiotic Galacto-Oligosaccharides from Lactose Using β-Galactosidases from Lactobacillus reuteri

Abstract

The beta-galactosidases (beta-Gals) of Lactobacillus reuteri L103 and L461 proved to be suitable biocatalysts for the production of prebiotic galacto-oligosaccharides (GOS) from lactose. Maximum GOS yields were 38% when using an initial lactose concentration of 205 g/L and at approximately 80% lactose conversion. The product mixtures were analyzed by capillary electrophoresis (CE) and high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Disaccharides other than lactose and trisaccharides made up the vast majority of GOS formed. The main products were identified as beta-d-Galp-(1-->6)-d-Glc (allolactose), beta-d-Galp-(1-->6)-d-Gal, beta-d-Galp-(1-->3)-d-Gal, beta-d-Galp-(1-->6)-Lac, and beta-d-Galp-(1-->3)-Lac. There were no major products with beta1-->4 linkages formed. Both intermolecular and intramolecular transgalactosylation were observed. d-Galactose proved to be a very efficient galactosyl acceptor; thus, a relatively large amount of galactobioses was formed. Monosaccharides could be conveniently separated from the mixture by chromatography using a strong cation-exchange resin.

Causes of the Production of Multiple Forms of β-Galactosidase byBacillus circulans

“…GOS are important prebiotics that enhance the proliferation of intestinal bifidobacteria and lactobacilli in the colon, which in turn promote human health by protecting individuals against infection, reducing the accumulation of harmful bacteria/toxic compounds, and facilitating the normal function of the gut. [8][9][10][11] Because of this, a number of studies have reported attempts to isolate a -galactosidase with high transgalactosylation activity from various microorganisms, [4][5][6][7][8] including Bacillus circulans, 12,13) Bifidobacterium adolescentis, 14) Lactobacillus reuteri, 15,16) and others. [17][18][19][20] Furthermore, the genes that encode -galactosidases from bacteria, including B. circulans, 21) Bifidobacterium bifidum [22][23][24][25] / Bifidobacterium infantis, 22,[26][27][28] L. reuteri, 29) L. plantarum, 30) and others, 20,31) have been cloned and sequenced, and the enzymes have been overexpressed in heterologous cells.…”

Evolved β-Galactosidases from Geobacillus stearothermophilus with Improved Transgalactosylation Yield for Galacto-Oligosaccharide Production

“…GOS are usually produced by the transglycosylation reaction during enzymatic hydrolysis of lactose. The proportion of transglycosylation to hydrolysis varies, depending on the different sources of enzymes (20,22,30,31). In most cases yields of oligosaccharides are rather low; presumably the products are substrates for the enzyme and undergo hydrolysis.…”

Kinetics and Metabolism of Bifidobacterium adolescentis MB 239 Growing on Glucose, Galactose, Lactose, and Galactooligosaccharides

“…In standardized large-scale production, trisaccharides to hexasaccharides are the main products; hence, commercial GOS occur as mixtures of various degrees of polymerization (DP) and glycosidic linkages and contain large amounts of glucose and unreacted lactose. The linkage between galactose moieties (mainly ␤1-4, ␤1-6, and ␤1-3), the efficiency of transgalactosylation, and the components in the final product depend upon the enzymes and the reaction conditions (3,7,25,30,34,39,41).As demonstrated in several in vitro and in vivo studies (5, 40), GOS resist hydrolysis by human digestive enzymes and are not absorbed on transit through the small intestine; therefore, they are available for fermentation by the colon-resident microflora. The utilization of GOS by the major intestinal bacteria has been investigated (25,34,46).…”

“…In standardized large-scale production, trisaccharides to hexasaccharides are the main products; hence, commercial GOS occur as mixtures of various degrees of polymerization (DP) and glycosidic linkages and contain large amounts of glucose and unreacted lactose. The linkage between galactose moieties (mainly ␤1-4, ␤1-6, and ␤1-3), the efficiency of transgalactosylation, and the components in the final product depend upon the enzymes and the reaction conditions (3,7,25,30,34,39,41).…”