Abstract
The establishment of the gut microbiota poses implications for short and long-term health. Bifidobacterium is an important taxon in early life, being one of the most abundant genera in the infant intestinal microbiota and carrying out key functions for maintaining host-homeostasis. Recent metagenomic studies have shown that different factors, such as gestational age, delivery mode, or feeding habits, affect the gut microbiota establishment at high phylogenetic levels. However, their impact on the specific bifidobacterial populations is not yet well understood. Here we studied the impact of these factors on the different Bifidobacterium species and subspecies at both the quantitative and qualitative levels. Fecal samples were taken from 85 neonates at 2, 10, 30, 90 days of life, and the relative proportions of the different bifidobacterial populations were assessed by 16S rRNA–23S rRNA internal transcribed spacer (ITS) region sequencing. Absolute levels of the main species were determined by q-PCR. Our results showed that the bifidobacterial population establishment is affected by gestational age, delivery mode, and infant feeding, as it is evidenced by qualitative and quantitative changes. These data underline the need for understanding the impact of perinatal factors on the gut microbiota also at low taxonomic levels, especially in the case of relevant microbial populations such as Bifidobacterium. The data obtained provide indications for the selection of the species best suited for the development of bifidobacteria-based products for different groups of neonates and will help to develop rational strategies for favoring a healthy early microbiota development when this process is challenged.
Highlights
The gastrointestinal tract is home to the intestinal microbiota that constitutes a very rich and complex microbial ecosystem
During early life, the microbiota is mainly constituted by Actinobacteria and Proteobacteria, becoming more diverse later on with the rise of Firmicutes and Bacteroidetes
The levels of the genus Bifidobacterium have been one of the microbiota characteristics more deeply affected by prematurity in different previous studies [25,38,40]. Our results extend these observations to the levels of specific Bifidobacterium species and to the global bifidobacterial community
Summary
The gastrointestinal tract is home to the intestinal microbiota that constitutes a very rich and complex microbial ecosystem. As with regard to the results obtained for the full-term vaginally delivered babies, no differences in the number of detected Bifidobacterium species were observed betwee6noef x12clusively breast-fed and formula/mix-fed groups (ranging between 12 and 14, depending on the sampling time) In this group, exclusive breast-feeding was found to promote higher relative proportions of B. longum subsp. In accordance with our results, other authors have demonstrated higher absolute levels of B. longum in full-term than in preterm babies during the first months of life, as is the case for one-month-old Brazilian infants [48] Delivery mode is another of the perinatal factors known to affect the general profile of the microbiota [49,50], and in this regard, our data indicate that the bifidobacterial community is not an exception, and it is affected by this factor. This study underlines the process of development of the bifidobacterial microbiota in the newborn during the first months of life and the factors driving it
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