Selectivity and efficiency of utilization of galactosyl-oligosaccharides by bifidobacteria.

Abstract

Neogalactobiose (.alpha.-D-galactopyranosyl .beta.-D-galactopyranoside), .beta.-D-galactopyranosyl .beta.-D-glucopyranoside, .beta.-D-galactopyranosyl .alpha.-D-glucopyranoside, .alpha.-D-galactopyranosyl .beta.-D-glucopyranoside (GII) and .alpha.-D-galactopyranosyl .beta.-D-fructofuranosyl-(2 .fwdarw. 6)-.beta.-D-fructofuranoside (Gf) were synthesized as sugar sources which might selectively and efficiently enhance the growth of bifidobacteria in the human intestines. Gf was synthesized by using levansucrase and the others by means of the Koenigs-Knorr reaction. The structures of these sugars were confirmed by enzymic hydrolysis. All of these sugars were utilized by almost all strains of Bifidobacterium tested. Among them, GII, Gf and stachyose were not utilized by Lactobacillus acidophilus or Streptococcus faecalis, and were utilized by only a few strains of Enterobacteriaceae (comparable to lactosucrose). As regards both the growth activity of bifidobacterial cells and the generation time of the cells, the 3 sugars were virtually as effective as lactose or lactosucrose.