Microbial succession is linked to phenylpropanoid remodeling, aroma softening, and quality improvement in naturally aged Artemisia argyi leaves.

Artemisia argyi is an edible, medicinal, and aromatic plant widely used in East Asia, whose leaves are traditionally aged after harvest to improve quality. However, the chemical and microbial basis of this practice remains unclear. Here, we investigated metabolic remodeling, microbial succession, quality formation, and microbial transformation potential during three years of natural postharvest aging using GC-MS, targeted metabolomics, microbial amplicon sequencing, bioactivity assays, and strain-based fermentation validation. Aging progressively reshaped volatile and nonvolatile metabolites and enhanced bioactivities, increasing ABTS scavenging activity to 67.41% and lowering the MIC against Staphylococcus aureus from 25 to 6.25 mg/mL. Pungent nitrogen-, sulfur-, and terpene-related volatiles declined continuously, as reflected by the decrease in the rOAV contribution of 1-nonen-3-one from 8.69% to 0.58%, whereas 21 of the 22 upregulated C15 volatiles were oxygenated derivatives, contributing to aroma softening. The phenylpropanoid network showed a stage-dependent transition characterized by chlorogenic acid depletion, transient caffeic acid accumulation, and enrichment of downstream derivatives, including ferulic acid, coniferin, and sinapoyl-related conjugates. These chemical changes closely paralleled microbial succession, with Pseudomonas, Sphingomonas, Pantoea, and Aeromicrobium preferentially associated with caffeic acid-related metabolites. Strain-based validation further showed that selected culturable isolates could degrade chlorogenic acid, and P-A1-3 promoted caffeic acid accumulation. Together, these findings indicate that AAL aging is an active maturation process involving microbial succession, phenylpropanoid remodeling, aroma softening, and functional enhancement.