Bacterial Peptidoglycan Extends Lifespan by Activating Lysosomal Activity through V-ATPase Binding

Summary Lysosomal dysfunction is a hallmark of aging, yet whether microbial components actively regulate this organelle to influence longevity remains unknown. Here, we identify bacterial peptidoglycan (PGN), a major cell wall component degraded by host lysozyme, as an evolutionarily conserved activator of lysosomal function that extends lifespan in both C. elegans and mice. We show that aging leads to an intestinal decline in lysozyme expression, which impairs bacterial cell-wall digestion and results in systemic PGN deficiency. Late-life PGN supplementation (starting at 18 months of age) significantly prolongs mouse lifespan and improves healthspan. Mechanistically, PGN localizes to lysosomes and directly binds V-ATPase subunits, enhancing ATP hydrolysis activity and promoting lysosomal acidification. This effect is abolished by V-ATPase inhibition (bafilomycin A1) or genetic disruption of lysosomal components ( cup-5 and vha-12 mutants), confirming that functional V-ATPase is strictly required for lysosomal function and the longevity benefit. Importantly, PGN restores lysosomal acidification in aged cells, alleviates cellular senescence markers, and improves multiple hallmarks of aging including locomotion and muscle integrity. Collectively, these findings reveal an evolutionarily conserved mechanism whereby hosts exploit bacterial cell wall components to maintain cellular homeostasis, establishing a gut microbiome–lysosome–longevity axis with implications for microbiome-based anti-aging interventions. Highlights Aging reduces intestinal lysozyme activity, depleting systemic PGN bioavailability PGN binds V-ATPase subunits, enhancing ATP hydrolysis and lysosomal acidification Bacterial PGN supplementation extends lifespan and improves healthspan PGN maintains multi-tissue lysosomal homeostasis and reduces cellular senescence during aging