Diversity and temporal stability of fecal bacterial populations in elderly subjects consuming galacto-oligosaccharide containing probiotic yoghurt

Denaturing gradient gel electrophoresis was applied to study the effect of 3-week consumption of probiotic yoghurt containing galacto-oligosaccharides (GOS) on intra-individual diversity and temporal stability of predominant bacterial, bifidobacterial, Lactobacillus-group, and Erec-group Eubacterium rectale–Clostridium coccoides fecal populations of elderly subjects. Diversity and temporal stability of the selected bacterial groups of elderly subjects were compared with those obtained from younger adults in our previous studies. In the present study, GOS-yoghurt consumption did not significantly affect diversity or temporal stability of the selected bacterial groups. On average, the Erec-group and the predominant bacterial and bifidobacterial populations remained almost stable, and the Lactobacillus-group was unstable in elderly subjects. No differences were found between elderly and younger adults in temporal stability of studied bacterial populations. However, the difference in diversity of predominant bacterial population and Erec-group bacteria was significantly higher in elderly subjects of this study as compared with younger adults from our previous studies.