[beef234]

Analysis of gut microbiota composition by bacterial 16S rRNA gene sequencing in a subset of Alzheimer’s patients (Supplementary Fig. 1A–E) revealed no significant change in alpha and beta diversities between control subjects and Alzheimer’s patients (Supplementary Fig. 1B–D). However, at phylum level, Alzheimer’s patients had a higher abundance of Bacteroidetes (Fig. 1C) reported to comprise many pro-inflammatory species,53 and a lower abundance of the phyla Firmicutes and Verruocomicrobiota, reported to produce beneficial metabolites.54 At the genus level, Alzheimer’s patients had on average a significant reduction in the relative abundance of Clostridium sensu stricto 1 and the short chain fatty acid (SCFA) butyrate-producing genera Coprococcus, which is associated with healthy ageing in general55 (Fig. 1C). In addition, similar to a previous report using a transgenic mouse model of Alzheimer’s disease,56 the relative abundance of the pathobiont genera Desulfovibrio was significantly increased in Alzheimer’s patients compared to cognitively healthy control subjects