design: For each donor, fecal-derived bulk DNA was extracted using the QIAamp DNA Stool Mini Kit (QIAgen, Nederland). Fecal samples were also examined for calprotectin levels. Deep metagenomic sequencing (30-50 million sequences per donor) was carried out using Illumina 150 b.p. (base pair) paired-end sequencing on the Novaseq6000 platform.