Elsevier

Research in Microbiology

Volume 157, Issue 9, November 2006, Pages 857-866
Research in Microbiology

Lactobacillus paracasei A survives gastrointestinal passage and affects the fecal microbiota of healthy infants

https://doi.org/10.1016/j.resmic.2006.06.007Get rights and content
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Abstract

This study focuses on the potentiality of a putative probiotic strain, Lactobacillus paracasei A, to survive gastrointestinal (GI) passage and modulate the resident microbiota of healthy infants. In a placebo-controlled study, 26 children aged 12–24 months received 100 g/day of either fermented milk containing strain A or pasteurized yogurt for four weeks. Fecal samples were analyzed before starting the administration, after 1, 3 and 4 weeks of consumption and after washout. The fate of strain A was followed by means of a newly developed PCR targeting a strain-specific genomic marker. The composition and dynamics of fecal microbial communities during the study were analyzed by culturing on selective media and by the PCR-denaturing gradient gel electrophoresis (DGGE) technique using universal and group-specific (Lactobacillus and Bifidobacterium) primers. The variation in enzymatic activities in infant feces during probiotic consumption was also analyzed. Strain A survived in fecal samples in most (92%) of the infants examined after 1 week of consumption, and temporarily dominated the intestinal Lactobacillus community. The administration of L. paracasei A led to a significant increment in the Lactobacillus population, while a moderate effect upon the main bacterial groups in the GI ecosystem was observed. Strain A also affected the diversity of the Lactobacillus and Bifidobacterium populations. The fecal bacterial structure of 1–2-year-old infants seems to combine neonate and adult-like features. The microbiota of these subjects promptly responded to probiotic consumption, later restoring the endogenous equilibrium.

Keywords

Lactobacillus
Probiotic strains
Fermented milk
Infants
Gastrointestinal content
PCR-DGGE

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