Characterization of the infant GUT bifidobacterial population by 16S amplicon pool pyrosequencing

One of the most complex microbial ecosystems is represented by the microbiota of the human gastrointestinal tract (GIT). Although this microbial consortium has been recognized to have a crucial impact on human health, its precise composition is still subject to intense investigation. Among the GIT bacteria, bifidobacteria represent an important commensal group, being one of the first microbial colonizers of the human gut. However, the prevalence and diversity of Bifidobacterium members, as part of the overall infant intestinal microbiota, has not yet been fully characterized, while some controversy exists about the abundance of this genus. In this work, we assessed the complexity of the infant intestinal bifidobacterial population by pyrosequencing of two hypervariable regions of the 16S rRNA gene. Eleven faecal samples were collected from healthy infants of different geographical origins (Italy, Spain or Ireland), feeding type (breast-fed or bottle fed) and mode of delivery (vaginal or caesarean delivery); faecal samples from four of the mothers were also analyzed. In contrast to several previously published metagenomic studies our analysis revealed a predominance of bifidobacteria in the infant gut as well as a profile of co-occurrence of bifidobacterial species in the infant’s intestine.