Combined PCR-DGGE fingerprinting and quantitative-PCR indicates shifts in fecal population sizes and diversity of Bacteroides, bifidobacteria and Clostridium cluster IV in institutionalized elderly

Aims: This study aimed at determining ageing-related shifts in diversity and composition of key members of the fecal microbiota by comparing institutionalized elderly (n = 17, 78-94 years) and young volunteers (n = 17, 18-31 years). Methods and results: A combination of molecular methods was used to characterize the diversity and relative abundance of total gastro-intestinal flora, along with relevant subsets within the genera Bacteroides, bifidobacteria and Clostridium cluster IV. The institutionalized elderly harbored significantly higher numbers of Bacteroides cells than control (28.5 +/- 8.6%; 21.4 +/- 7.7%; p = 0.016) but contained less bifidobacteria (1.3 +/- 0.9, 2.7 +/- 3.2%, p = 0.026) and Clostridium cluster IV (26.9 +/- 11.7%, 36.36 +/- 11.26%, p = 0.036). The elderly also displayed less total Bacteria diversity and less diversity with the Clostridium cluster IV (p < 0.016) and Bacteroides. Conclusion: Despite high individual variations, our analyses indicate the composition of microbiota in the elderly comprises a less diverse subset of young healthy microbiota. Significance and impact of the study: A better understanding of the individual composition of the human microbiota and the effects of ageing might result in the development of specifically targeted supplementation for elderly citizens in order to support healthy ageing. (C) 2009 Elsevier Inc. All rights reserved.