Colonization of the Murine Gut by Bifidobacterium bifidum and Clostridium perfringens during Ageing

The level in bifidobacteria colonizing the human gut is decreasing during ageing whereas clostridia proliferate. It was hypothezised that the poorly growing bifidobacteria became unable to exert colonization resistance against clostridia. In order to analyse the relationship between bifidobacteria and clostridia; we investigated in germfree mice the bifidobacterial colonization of the gut according to the diet and to the endogenous bifidus factors (BB) contained in the mucus. The slower colonization might be related to the lack of bifidogenic factors in the control food (SHF mice) whereas the low contamination level found later in SHF and CHF mice would be the result of the modification to the mucus composition induced by either diet. In a second step, C. perfringens was given to B. bifidum monoassociated mice fed the most efficient food and we studied the colonization by both strains during ageing. In conclusion, B. bifidum did not exert any colonization resistance against C. perfringens, neither did C. perfringens against B. bifidum. As the intestinal bifidobacterial growth seemed to depend on the intestinal glycoprotein concentration, the relative decrease observed in dixenic mice might be the result of a change in the mucus secretion induced by C. perfringens colonization.