Gut microbiome-driven longevity mechanisms in giant pandas: age-associated gut microbial shifts, functional pathways, and probiotic insights.

Microbiome-mediated longevity mechanisms in conservation wildlife remain largely uncharacterized, particularly in species with specialized diets where host-microbe coevolution plays essential compensatory roles. We conducted cross-sectional metagenomic profiling of gut microbiota in 82 captive giant pandas (Ailuropoda melanoleuca) spanning juvenile, adult, and geriatric cohorts. The cohort included 14 long-lived individuals (≥25 years). Our approach integrated enterotype analysis, functional pathway characterization, and lactic acid bacteria (LAB) isolation. Age-specific compositional shifts occurred throughout the lifespan, characterized by reciprocal dominance between Bacillota (declining from 84.77% to 10.26%) and Pseudomonadota (increasing from 12.74% to 81.86%). Streptococcus dominated adolescent microbiomes, followed by a transition to cellulose-degrading taxa in young adults. Enterotype analysis revealed 4 distinct community types with age-dependent succession patterns. Long-lived pandas exhibited elevated abundance of Akkermansia muciniphila, Bifidobacterium longum, Lactobacillus intestinalis, and Ruminococcus gnavus. Functional profiling revealed age-dependent shifts from nucleotide and amino acid biosynthesis in young animals to lipid metabolism and amino acid degradation in aged individuals. Carbohydrate-active enzyme analysis demonstrated enrichment of cellulolytic enzymes (such as GH3, GH5, and GH9) in long-lived adults. Biosynthetic gene cluster profiling revealed progressive age-associated accumulation of genes encoding NRPS, RiPP-like, arylpolyene, and terpene biosynthetic pathways. Culture-based isolation from fecal samples of long-lived giant pandas yielded 98 LAB strains representing 8 species (Lactobacillus johnsonii, Limosilactobacillus reuteri, L. intestinalis, among others), including 89 non-hemolytic strains that were sensitive to 6 common antibiotics. These findings suggest potential cross-species conservation of microbiome-longevity mechanisms, with implications for understanding physiological adaptations in specialist herbivores and applications in conservation medicine.