Haruji Sawada

Structure of a galactan from cell walls of Bifidobacterium catenulatum YIT4016

A structural study was carried out on a galactose-rich polysaccharide fraction isolated from cell walls of Bifidobacterium catenulatum YIT4016 after N-acetylmuramidase digestion. The polysaccharide contained galactose and glucosamine in a molar ratio of 16.9:1.0. Data obtained by 13C NMR spectroscopy showed that the backbone chain of this polysaccharide is composed of galactofuranose residues, while the branches consist of galactopyranosyl residues. Furthermore, the data obtained from NaIO4 oxidation, partial methanolysis and methylation analysis indicated that this polysaccharide consists of a trisaccharide repeating unit having the following structure: [sequence: see text]

Structural studies on a cell wall polysaccharide from Bifidobacterium longum YIT4028

The major fraction of rhamnogalactan was isolated from the cell wall of Bifidobacterium longum YIT4028 by treatment with N-acetylmuramidase. This polysaccharide was composed of rhamnose and galactose in a molar ratio of about 2:3. The 13C NMR spectrum indicated that it contained a pentasaccharides repeating unit. This observation, and the results of Smith degradation, partial acid hydrolysis and methylation analysis led to the conclusion that its structure is [formula: see text]

Effects of the Cell Wall of Kluyveromyces marxianus YIT 8292 on the Plasma Cholesterol and Fecal Sterol Excretion in Rats Fed on a High-Cholesterol Diet

The cellular components involved in the hypocholesterolemic activity of Kluyveromyces marxianus YIT 8292 were examined in rats fed on a high-cholesterol diet. Whole cells (KM) were heated at 115 °C for 10 minutes and fractionated into water-soluble extract 1 and the insoluble residue (KM-CW). After mechanical disruption by glass beads, KM-CW was separated into the cell wall (KM-W) and water-soluble extract 2. Plasma total cholesterol was decreased by feeding KM-CW or KM-W, but was not changed by feeding extract 1 or extract 2. Feeding KM-CW and KM-W increased the fecal sterol excretion and concentration of short-chain fatty acids (SCFA) in the cecum. The hypocholesterolemic activity of KM-CW was completely abolished by the enzymatic degradation of α-mannan and β-glucan. These results suggest that α-mannan and β-glucan were the major active components of KM, and that its hypocholesterolemic activity may be attributable to the increasing fecal sterol excretion and/or production of SCFA.

Potent Hypocholesterolemic Activity of the Yeast Kluyveromyces marxianus YIT 8292 in Rats Fed a High Cholesterol Diet

The hypocholesterolemic activities of 81 yeast strains were examined in rats fed a high cholesterol diet (HCD). Male Wistar rats were fed an HCD or an HCD supplemented with 10% yeast for 7 d. It was found that the hypocholesterolemic activities of the yeasts varied remarkably between strains. Kluyveromyces marxianus YIT 8292 exhibited the most potent hypocholesterolemic activity among the yeasts that were tested. K. marxianus YIT 8292 significantly decreased not only plasma total cholesterol but also liver total cholesterol when administered as a dietary admixture at a concentration of 3%. In contrast, brewer’s yeast and baker’s yeast, which have been predominantly used for food, did not exhibit hypocholesterolemic activity even when administered at a concentration of 10%. These results suggest that K. marxianus YIT 8292 may be utilized as a novel food material with the ability to contribute to the prevention of hypercholesterolemia.