Diversity of Bifidobacteria within the Infant Gut Microbiota

Francesca Turroni,Elena Foroni,Colm Kerr,Douwe Van Sinderen,Fabio Fuligni,Julian R Marchesi,Jonathan Hourihane,Daniel A Pass,Paul W O’Toole,Gianluca De Bellis,Marco Severgnini,Deirdre Murray,Clelia Peano,Abelardo Margolles,Marcus J Claesson,Miguel Gueimonde,Marco Ventura,Josef Neu

doi:10.1371/journal.pone.0036957

Abstract

BackgroundThe human gastrointestinal tract (GIT) represents one of the most densely populated microbial ecosystems studied to date. 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 microbiota, bifidobacteria represent an important commensal group, being among the first microbial colonizers of the gut. However, the prevalence and diversity of members of the genus Bifidobacterium in the infant intestinal microbiota has not yet been fully characterized, while some inconsistencies exist in literature regarding the abundance of this genus.Methods/Principal FindingsIn the current report, we assessed the complexity of the infant intestinal bifidobacterial population by analysis of pyrosequencing data of PCR amplicons derived from two hypervariable regions of the 16 S rRNA gene. Eleven faecal samples were collected from healthy infants of different geographical origins (Italy, Spain or Ireland), feeding type (breast milk or formula) and mode of delivery (vaginal or caesarean delivery), while in four cases, faecal samples of corresponding mothers were also analyzed.ConclusionsIn contrast to several previously published culture-independent 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.

Highlights

The gastrointestinal microbiota plays a crucial role in health and disease of the host through its impact on nutrition, pathogenesis and immunology [1]
In contrast to several previously published culture-independent 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
The decrease in the rate of phylotype detection and the plateauing of all the diversity indices for each sample demonstrated that a large part of the diversity in these libraries had been detected (Fig. 1)

Summary

Introduction

The gastrointestinal microbiota plays a crucial role in health and disease of the host through its impact on nutrition, pathogenesis and immunology [1]. Studies employing murine models have highlighted the critical role played by the gut microbiota in the development of a properly functioning gastrointestinal tract [2,3]. Recent advances in culture-independent techniques for microbial community analysis have highlighted the diversity, individual variability and complexity of the human gut microbiota [12,13,14]. For a long time bifidobacteria were considered to represent the dominant component of the neonatal gut microbiota, based on both culture-based techniques and analysis using species-specific DNA probes [14,20,21,22,23,24]. The human gastrointestinal tract (GIT) represents one of the most densely populated microbial ecosystems studied to date This microbial consortium has been recognized to have a crucial impact on human health, its precise composition is still subject to intense investigation. The prevalence and diversity of members of the genus Bifidobacterium in the infant intestinal microbiota has not yet been fully characterized, while some inconsistencies exist in literature regarding the abundance of this genus

Methods

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Discussion

Conclusion