Summary

The composition of faecal flora of NC mice was compared with that of CF#l mice. NC- and CF#J-germfree (GF) mice were cage-mated with NC- or CF#l-conventional (CV). mice in an isolator. The faecal flora of these ex·GF mice was dependent on the recipient mouse strain modifying colonization by the donor mouse bacteria. Although NC- and CF#I-pups removed by hysterectomy were fostered to different strains, almost all these mice at 8 weeks old had a strain characteristic pattern of faecal flora regardless of the foster strains. In GF mice mono-associated with a Lactobacillus strain or a Bifidobacterium strain isolated from faeces of CV mice, the numbers of these bacteria in the stomach and small intestine of NC mice were lower than thos