title: Lactobacillus paracasei A survives gastrointestinal passage and affects the fecal microbiota of healthy infants.
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.
authors.affiliation: Department of Science and Technology, University of Verona, Strada Le Grazie, 15, 37134 Verona, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Marzotto
authors.forename: Claudio
authors.initials: C
authors.lastname: Maffeis
authors.forename: Thomas
authors.initials: T
authors.lastname: Paternoster
authors.forename: Rossano
authors.initials: R
authors.lastname: Ferrario
authors.forename: Lucia
authors.initials: L
authors.lastname: Rizzotti
authors.forename: Maristella
authors.initials: M
authors.lastname: Pellegrino
authors.forename: Franco
authors.initials: F
authors.lastname: Dellaglio
authors.forename: Sandra
authors.initials: S
authors.lastname: Torriani
mesh_terms: D043302:Cultured Milk Products / Q000382:microbiology; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005243:Feces / Q000382:microbiology*; D041981:Gastrointestinal Tract / Q000382:microbiology*; D006801:Humans; D007223:Infant; D007778:Lactobacillus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D050296:Microbial Viability; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D019936:Probiotics / Q000008:administration & dosage*; D019105:Random Amplified Polymorphic DNA Technique; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial