Metabolic Pathway of Human Milk Oligosaccharides in Bifidobacteria
Motomitsu Kitaoka, Takane Katayama, and Kenji Yamamoto
from: Lactic Acid Bacteria and Bifidobacteria: Current Progress in Advanced Research (Edited by: Kenji Sonomoto and Atsushi Yokota). Caister Academic Press, U.K. (2011)
It has long been considered that human milk oligosaccharides (HMOs) are the growth-promoting factors for bifidobacteria, which makes bifidobacteria the predominant intestinal microbiota in breast-fed infants. However, the mechanism responsible for the selective growth of bifidobacteria has not yet been identified because of the difficulty caused by the complicated content of HMOs, which includes more than 100 kinds of molecules. The lacto-N-biose I (LNB) hypothesis made it possible to investigate the bifidobacterial metabolism of HMOs systematically. As predicted by the LNB hypothesis, several extracellular enzymes that liberate LNB from HMOs have been identified from Bifidobacterium bifidum JCM1254. The intracellular metabolic pathway of bifidobacteria specific to galacto-N-biose and LNB, led by β-1,3-galactosyl-N-acetylhexosamine phosphorylase, has been fully characterized. Meanwhile, a practical method to produce LNB on a large scale has been established. The long-standing enigma of the bifidus factor present in human milk might be clarified in the near future read more ...