Prebiotic Oligosaccharides: Comparative Evaluation UsingIn VitroCultures of Infants' Fecal Microbiomes

Abstract

ABSTRACTThe objective of this study was to systematically assess the bifidogenic effect of three commonly used prebiotic products usingin vitrocultures of infant fecal samples. Fresh stool samples collected from six term infants, each exclusively fed human milk (n= 3) or infant formula (n= 3), at 28 days of age were used as inocula. The following prebiotic products were added at concentrations applicable to infant formula: Vivinal GOS 15 (containing 28.5% galacto-oligosaccharide [GOS]) at 7.2 g/liter, Beneo HP (99.5% long-chain inulin [IN]) at 0.8 g/liter, Beneo Synergy 1 (enriched oligofructose and inulin [OF-IN]) at 4 g/liter, and a combination of Vivinal GOS 15 (7.2 g/liter) and Beneo HP (0.8 g/liter) (GOS-IN). The growth of total bacteria,Bifidobacterium,Bacteroides,Bifidobacterium longum, andEscherichia coliwas quantified using specific quantitative PCR (qPCR).Bifidobacteriumwas also enumerated on selective Beerens agar plates, with representative colonies identified by sequencing of their 16S rRNA genes. Volatile fatty acids (VFA) and pH in the cultures were also determined. Irrespective of the feeding methods, the GOS product, either alone or in combination with Beneo HP, resulted in substantially higher growth of total bifidobacteria, and much of this growth was attributed to growth ofB. longum. Beneo Synergy 1 also increased the abundance of total bifidobacteria andB. longum. Corresponding to the increases in these two bacterial groups, acetic acid concentrations were higher, while there was a trend of lowerE. colilevels and pH. The lower pH and higher acetic acid concentration might be directly responsible for the lowerE. colipopulation. At the concentrations studied, the GOS product was more bifidogenic and potent in inhibitingE. colithan the other products tested. These results suggest that supplementation of infant formula with GOS may increase intestinal bifidobacteria and benefit infant health.