Molecular monitoring of fecal microbiota in healthy adults following probiotic yogurt intake

• The impact of probiotic yogurt intake on fecal bacterial community profile was evaluated.
• A strong presence of the probiotic strains was observed after consumption in fecal samples.
• B. animalis ssp. lactis BB-12 and L. acidophilus LA-5 did not perturb the bacterial indicators.

Probiotic consumption is known to influence the composition of intestinal microbiota by significantly increasing the counts of the target probiotic strains. However it is still unknown whether other bacterial indicators of the fecal microbiota are affected. In this study, two culture-independent molecular methods were used to profile the fecal microbiota of healthy human adult subjects: Terminal restriction fragment length polymorphism (T-RFLP) and quantitative PCR (qPCR). The impact of probiotic intake on bacterial community profile as well as effect on the variation of some indicator fecal microbiota species were assessed on fecal DNA samples obtained during the clinical trial of a commercial yogurt. T-RFLP of fecal samples showed no difference in profile variation between placebo or yogurt consumption (Bray–Curtis distance). Quantification by qPCR of some elements of fecal populations and endogenous Bifidobacterium species revealed that beyond the increase in probiotic species (Bifidobacterium animalis subsp. lactis and Lactobacillus acidophilus LA-5), the variations observed were largely due to inter-subject variation rather than treatment effect. The molecular profile of the fecal microbiota of healthy adults is not disturbed by commercial probiotic yogurt consumption despite a strong presence of the probiotic strains.