characterization of structure and cellular immunity bioactivity of milk-derived galactooligosacchrides prepared by lactobacillus delbrueckii subsp. bulgaricus fermentation

In this study, the milk-derived galactooligosaccharides (gos) were produced by lactobacillus delbrueckii subsp. bulgaricus and refined by an ultrafiltration-nanofiltration continuous membrane. by further investigation, we found that the gos product purified by gel permeation chromatography mainly contained low molecular weight disaccharide and trisaccharide, that is, 4-β-galactobiose and tri-galacto-oligosaccharides. the cellular immune activity of the purified gos was evaluated by using intestinal epithelial cells (iecs). results showed that gos could significantly (p< 0.05) promote iecs proliferation in a dose and time dependent manner, and the relative proliferation rate after 24 hours culture was high up to 158% at the concentration of 100 μg ml-1, which was three time the value after 4 hours culture without gos. moreover, the production of il-6 was observably increased and up to 133.54 ng l-1 with addition of 100 μg ml-1 gos. these data implied that the purified gos might have a role in promoting the immune adjustment, which could be utilized as a novel and natural immunoregulatory agent in the field of medicine and functional food. this work also revealed that the employment of transgalactosylation activity of β-galactosidase derived from the fermentation of probiotics such as lactobacillus delbrueckii subsp. bulgaricus would enhance the value of the milk product due to the form of gos.