Performance of bifidobacteria in oat-based media.

Thirteen Bifidobacterium strains were isolated form the faeces of healthy elderly subjects. The ability of the isolated strains to acidify and survive in an oat-based medium was assessed and compared to a commercial starter Bifidobacterium strain. Since adhesion to the intestinal mucosa is one of the main selection criteria for potential probiotics, the influence of the oat medium on the ex vivo adhesion of the isolates to both human colonic tissue and to mucus from elderly subjects was assessed. Seven of the fourteen strains survived the 24-h fermentation, six of these acidified the medium to below pH 5. Supplementation of the medium with soy protein had a negative effect on survival and the acidification. The strains isolated from the elderly subjects were found to adhere in high levels to immobilised intestinal mucus from elderly. However, their adhesion to colonic tissue was significantly lower. Prior exposure to the oat-based medium increased the adhesion of two of the strains.