This project aims to determine the bacterial microbiome in children and if probiotics may affect the bacterial composition. Fecal samples from children will be used. All bacteria carry 16s rRNA and a gene encoding it. Some parts are conserved and others variable between species. Conserved areas at the ends of the gene can be targeted by PCR and thus the whole gene can be amplified. By using a Nanopore-based 16s analysis the whole 16s gene can be sequenced and the true composition of bacteria can therefore be determined, as compared to sequencing shorter parts of the gene where this is not always achieved. 16s is simpler and require less expensive sequencing compared to metagenomic sequencing of fecal samples, as only bacterial DNA is sequenced. In this study, no human genetic analyses will be performed.