Identification of the main environmental factors impacting the gut microbiota composition in 167 healthy Danish children

Numerous studies have been performed in the past years on human gutmicrobiota, but few focused on factors influencing the composition in earlyyouth. To gain more insights on this topic, 16S rRNA high-throughputamplicon sequencing was performed on two datasets of healthy danishchildren.Samples were obtained from a cohort of children aged between 1 and 7years, attending different daycares. Two datasets were investigated: onewas sequenced in this study and included 167 children; the other derivedfrom a previous longitudinal study performed on 32 timeseries (6 sampleseach). Some individuals were in common between the datasets, and acomparison gave consistent results, but some differences were found inrare taxa. Age was the main factor influencing microbial diversity. Alphadiversity was higher in children 3-7 years old and beta diversity clearlyseparated children 1-2 and 3-7 y.o.. Children aged 1-2 showed higher levelsof Escherichia-Shigella. Samples harbouring Blastocystis hominis wereclustered according to beta diversity and revealed an interesting associationamong B. hominis, Prevotella and Eubacterium ruminantium.Preschool microbiota analysis was improved clustering children by age.Inclusion of data from previous studies reinforced the outcomes andprovided new insights on gut microbiome in early youth.