Characteristics and longitudinal stability of Gut Microbiota in healthy individuals across different age groups

Fecal microbiota transplantation (FMT) efficacy relies on donor microbiome composition and temporal stability, yet the influence of donor age remains inadequately investigated. This longitudinal analysis addressed this gap by examining 81 healthy individuals (3-30 years), stratified into four age groups, who provided monthly fecal samples over 12 months (<i>n</i> = 972 samples). Gut microbiota composition (16S rDNA sequencing) and temporal stability were assessed using Bray-Curtis dissimilarity, intraclass correlation coefficient (ICC), and genus-level co-occurrence network analysis. Results demonstrated a strong age-dependency in microbiota stability. The teenage cohort (13-17 years) exhibited the highest stability, characterized by minimal fluctuations in α- and β-diversity and significantly stronger network centrality. Furthermore, specific genera, notably <i>Faecalibacterium</i> and <i>Bifidobacterium</i>, displayed exceptionally high ICC values (>0.90), identifying them as core taxa associated with temporal consistency. These findings underscore the critical role of donor age in microbial stability and highlight teenagers as possessing optimal microbiota characteristics for FMT. They strongly support the development of an ICC-based screening framework to enhance donor selection protocols.