Abstract
Herein, we report the abundance and prevalence of HMO-metabolizing genes, specifically those of Bifidobacterium infantis, in fecal samples from human infants. Forty dyads were enrolled, and each mother collected a fecal sample from her infant at six months of age. Genomic DNA was extracted, and quantitative real-time PCR was used to determine gene abundance. The mode of delivery was not associated with gene abundance. Several gene regions, Sia (a sialidase), B. inf (16S), and GH750 (a glycoside hydrolase), were more abundant in the feces of human milk-fed infants (p < 0.05). Others, Sia and HC bin (16S), tended to be less abundant when a larger percentage of an infant’s diet consisted of solids (p < 0.10). When accounting for solid food intake, human milk exposure was positively associated with Sia and B. inf (p < 0.05) and tended to be related to the abundance of the GH750 and HC bin (p < 0.10) gene regions. With further development and validation in additional populations of infants, these assays could be used to group samples by dietary exposure even where no record of dietary intake exists. Thus, these assays would provide a method by which infant human milk intake can be assessed quickly in any well-equipped molecular biology laboratory.
Highlights
Many components found in human milk such as human milk oligosaccharides (HMOs) are still missing from most modern infant formulas [3,4,5,6]
When we considered detection of the following five genes, Sia, GH492, Inf 2348, GH750, and HH, at a level that was “more positive” or “very positive,” we found that the stool of the human milk-fed infants harbored a more diverse set of HMO genes than that of the non-human milk-fed infants (p = 0.0148)
When accounting for solid food intake, human milk exposure continued to be associated with Sia (p = 0.0247) and B. inf (p = 0.0165) gene abundance
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. HMOs benefit infants consuming human milk due to their ability to block specific pathogens from attaching to the surface sugars of epithelial cells [7]. This can prevent disease in the gastrointestinal tract and even protect infants from respiratory and urinary tract infections [8]. Microorganisms 2021, 9, 1352 formula-fed have a more diverse Bifidobacterium population These diverse populations include B. longum, B. breve, and Bifidobacteria species more commonly seen in adults, such as B. adolescentis [9]. We hypothesized that infants who test positive for B. infantis HMO-metabolizing genes would have consumed a larger percentage of human milk in their diet.
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