Fig. 1

Experimental Overview. A Mouse grouping and B microbiota transfer timeline overview. Young (3 m, blue), old (18 m, white), or aged (24 m, orange) SPF C57BL/6 males were randomly allocated to experimental cages by age group 2 weeks before the start of the experiment. Existing microbiota were depleted by a 3-day antibiotic cocktail (Abx; oral gavage and drinking water). Post-antibiotic washout, recipients were rehoused in donor cages containing soiled bedding and fecal pellets and were twice delivered donor microbiota by oral gavage of fecal slurry preparation from 3-, 18-, or 24-month-old donors. Antibiotic-only groups were returned to their home cage and received no FMT