[Host-Bifidobacterium interactions in the axenic mouse: partial characterization of bifidogenic factors in the...

Growth factors for Bifidobacterium bifidum were detected in faeces of axenic mice strain C3H. Most of these factors were found in the nondialyzable fraction obtained after aqueous extraction and dialysis. SDS-PAGE and filtration chromatography on Sepharose 4B revealed that many glycosylated components harbored a bifidigenic activity. Intestinal colinization of mice by B. bifidum involved the utilization and eventually the disappearance of the intestinal bifidigenic factors. There was no change in the protein concentration in fecal extracts, but the total hexose concentration was lower. Comparison of electrophoretic PAGE profiles after periodic acid Schiff coloration showed that bacteria used up the glycosylated fractions of many glycopeptides, particularly those of mucins and four glycoproteins. There was no correlation between the hexose concentration detected in every active fraction and the degree of in vivo degradation of bifidigenic factors. The attack on active glycopeptides having a molecular mass greater than 670 kDa thus revealed hexose sites that were not detectable previously by the phenol - sulfuric acid method. However, the amount of bifidigenic factors detected in vitro allowed us to measure the importance of the degradation of a component by B. bifidum in vivo.