The older infants in our study received a more diverse diet. Significant higher
numbers of Bifidobacterium were observed in infants versus adults and seniors. We conclude, therefore, that the high level of Bifidobacterium observed in our panel was not strictly correlated to breast feeding and could be considered as a broad signature of the infant microbiota during the first year of life. This observation confirms previous reports indicating that the gastrointestinal FK228 tract is first colonized by facultative anaerobes, such as E. coli [23]. Strict anaerobes, such as Clostridium, colonize at later stages, as can be seen by the relatively low levels of C. leptum and C. coccoides in infants [23]. Our results are in agreement with these previous reports. We hypothesize that diet change must be considered among the primary causes for such a shift of microbiota between infants and adults. In the case of elderly subjects, our qPCR results indicated a significant increase in the counts of E. coli when compared to adults. This data is consistent with other publications indicating that elderly subjects harbor https://www.selleckchem.com/products/sn-38.html a different E. coli microbiota profile compared to younger adults [26–28]. Concerning the microbiota of the elderly, a number of authors reported a reduction in the numbers and diversity of many protective commensal anaerobes, such as Bacteroides
and Bifidobacteria. These reports also suggest a shift in the dominant bacterial species
[17, 19]. The Firmicutes to Bacteroidetes ratio was already shown to be of significant relevance in signaling human gut microbiota status [7]. This previous work focused on lean individuals and used 16S ribosomal RNA gene sequencing. Our measurements of the Firmicutes/Bacteroidetes ratio in adults obtained by our species-specific qPCR are in agreement with those obtained by Ley et al. [7]. Compared with young adults, the elderly have a different digestive Sapitinib datasheet physiology, characterized at a physiological level by a reduction in transit and of digestive secretions. These changes could explain the observed changes in the fecal microbiota associated with advancing age. Conclusion Our results illustrate a measurable progression of bacterial species colonizing Cepharanthine the human intestinal tract during different stages of life. This progression is easily observed and quantified using qPCR to evaluate numbers of bacteria belonging to major dominant and subdominant groups of the human fecal microbiota. The Firmicutes/Bacteroidetes ratio undergoes an increase from birth to adulthood and is further altered with advanced age. This ratio appears applicable in highlighting variations between infants, adults and the elderly. It can be linked to overall changes in bacterial profiles at different stages of life.