Microbiome-metabolome integration reveals fermentation-driven divergence in bioactive compound profiles of Cardamine violifolia leaf pickles

<i>Cardamine violifolia</i> is an emerging cruciferous vegetable rich in nutrients and bioactive components. This study investigated the microbial community and metabolite profiles in <i>C</i>. <i>violifolia</i> leaf pickles prepared using three fermentation methods: natural fermentation (NF), inoculation with <i>Lactiplantibacillus plantarum</i> (LP), and inoculation with <i>Leuconostoc mesenteroides</i> (LM). Results revealed that fermentation significantly altered the microbial composition, with Firmicutes becoming the dominant phylum. <i>Lactococcus</i> and <i>Weissella</i> were predominant in both the NF and LM groups, while <i>Lactiplantibacillus</i> dominated in the LP group. Metabolomic analysis identified 865 metabolites in total, with amino acids, lipids, and alkaloids representing the most abundant classes. Fermentation enhanced the production of <i>bioactive compounds (e.g., alkaloids, phenolic acid, flavonoids)</i>, particularly in the LP group. Correlation analysis indicated a strong relationship between specific microorganisms and active metabolites. These findings suggest that fermentation not only improved the edible and nutritional value of <i>C. violifolia</i> leaf pickles but also enhanced their potential health benefits.