There is ample evidence suggesting that modulations in gut microbiota play an important role in inflammation and immunity. In particular, the microbiota of children is highly susceptible to environment influences, such as infections. Consequently, probiotics and their ability to promote and support a healthy microbiome have been increasingly studied. This study aimed at investigating the effects of a probiotic supplement (Bacillus subtilis DE111) on the microbiome composition of preschool aged children attending day care. Healthy children aged 2-6 years old were randomised to receive either probiotic or placebo once a day for 8 weeks. No significant changes of the overall microbiome equilibrium were seen in between the two groups or from baseline to week 8. However, alpha diversity was increased in the probiotic group from baseline to week 8 (P<0.05), with no change in the placebo group. A decrease in the Firmicutes/Bacteroidetes ratio following probiotic supplementation (P<0.05) was also observed. Differential abundance analysis revealed an increase in Alistepes (P<0.01), Bacteroides (P<0.05), Parabacteroides (P<0.01), Odoribacter (P<0.001) and Rikenellaceae (P<0.001) in the probiotic group, most of which are involved in inflammation reduction. In addition, a decrease in Eisenbergiella (P<0.001), Lactobacillales (P<0.01) and Streptococcaceae (P<0.01), which is considered pro-inflammatory, were also observed in the probiotic group. Together with a reduction of the F/B ratio observed in the probiotic group, these results suggest probiotic supplementation with Bacillus subtilis DE111 introduce subtle but positive changes in the microbiome of children aged 2-6 years old.
Keywords: Bacillus subtilis DE111; gut microbiome; paediatric population.