摘要：Recently, there has been great interest in the biological effects of equol, a metabolite of daidzein produced by intestinal flora. In this study, we used a newly isolated intestinal bacterium from healthy human faeces to investigate the effects of intestinal bacteria on the in vitro metabolism of daidzein by faecal flora in mice and a human male equol producer. The 16S rDNA partial sequence (1394 bp) of strain TM-20 that was isolated from infant faeces exhibited a 99% similarity to that of Bifidobacterium pseudocatenulatum . Therefore, this strain was identified as belonging to the genus Bifidobacterium. In faecal suspensions from mice, equol concentrations were significantly lower in the control faecal suspension than in the faecal suspension supplemented with the high concentration of strain TM-20. However, equol concentrations were significantly higher in the control faecal suspension than in the faecal suspension supplemented with the low concentration of strain TM- 20. In faecal suspensions from a human male equol producer, equol concentrations were lower in the control faecal suspension than in the faecal suspension supplemented with the high concentration of strain TM-20. However, equol concentrations were higher in the control faecal suspension than in the fecal suspension supplemented with the low concentration of strain TM-20. Metabolic activity of the faecal equol production in mice and humans may be changed by some types of bifidobacteria. To our knowledge, this is the first report of a Bifidbacterium sp. that is capable of changing the faecal equol production from daidzein in vitro.Key words: daidzein, equol, faecal flora, bifidobacteria
