Molecular characterization of intestinal microbiota in infants fed with soymilk

Intestinal bacteria play an important role in the postnatal development of the immune system. The composition of gut microbiota is profoundly influenced by the infant's diet, but there is little information about the effects of soymilk on the composition of intestinal biota. The present study was designed to investigate the intestinal ecosystem of the newborn in relation to the consumption of soymilk. Twelve infants had their bovine milk-based formula replaced with soymilk. The intestinal microbial composition of the infants was investigated before and after the change by means of polymerase chain reaction-denaturing gradient gel electrophoresis. In addition, species-specific amplification of 10 Bifidobacterium species, 3 Ruminococcus species, and the Bacteroides group was performed. Denaturing gradient gel electrophoresis analysis revealed bacterial profiles characterized by numerous bands typical for each subject. No variations were detected by species-specific polymerase chain reaction. The data demonstrate that soymilk feeding does not alter the intestinal flora of infants and decrease the intestinal bifidobacterial population.