APP and Alzheimer disease: The abundance of some bacteria exhibited substantial changes at the genus and family levels in fecal samples from the APP/PS1 mice, while the OMO treatment changed those variations; in particular, obvious increases in the abundance of Lactobacillus, Allobaculum, Lactobacillaceae, and Lachnospiraceae were observed, indicating that OMO had a prebiotic role in protecting against intestinal dysbacteriosis in the AD model animals.