All donors collected feces independently using a collection kit. Samples were collected in a 1litre plastic container, sealed in a plastic bag containing GENbag anaer and stored for a maximum of 2 h. Fresh feces were homogenized in a stomacher bag (Laboratory Blender, Stomacher ® 400 Circulator, EU) with sodium phosphate buffer for 30 s and the resulting 24% fecal slurry was filtered through a nylon mesh.