Effects of Prebiotics and a Synthetic Microbiome Consortium on the Composition and Metabolites of the Elderly Gut Microbiota In Vitro

A 24 h artificial colon fermentation was performed to assess the effects of a prebiotic MIX and synthetic consortium (S7) on gut microbiota composition and microbial metabolite production in clinically stratified older adults (healthy and frail). Treatments included supplementation of the donor microbiota with a synthetic microbial consortium (S7), a prebiotic mix (MIX), and a combination of MIX and S7 (MIX+S7). The S7 treatment decreased the alpha diversity of long-stay-dwelling donor (LS, “frail”) microbiota and increased the relative abundance of S7 taxa at 16 h. MIX alone caused the enrichment of reportedly beneficial genera such as Coprobacillus and Eubacterium in community-dwelling donor (CM, “healthy”) microbiota and Citrobacter and Faecalibacterium in LS microbiota. The MIX+S7 treatment sustained higher overall S7 species richness and consortium taxon abundance at 24 h. Both MIX and MIX+S7 treatments enhanced short-chain acid production compared to control. These findings highlight the differential responses of microbiota from distinct elderly health strata to prebiotic and microbial consortia supplementation.