Closed solid-state vinegar brewing system: Multi-omics decoding of microbial succession and flavor metabolic network dynamics

The closed solid-state vinegar brewing system has revolutionized traditional vinegar production by introducing standardized fermentation protocols, resulting in consistent and high-quality flavor profiles. However, the intricate mechanisms governing microbial succession during the acetic acid fermentation phase within this system remain elusive. Similarly, the complex interplay between flavor components and key microbial communities is not fully understood. In this study, advanced metabolomic analysis was employed, leading to the identification and characterization of a comprehensive array of 9 organic acids, 16 free amino acids, and 64 volatile flavor substances. Metatranscriptome analysis further elucidated the dynamic shifts in microbial communities across distinct fermentation stages. Specifically, Lactobacillus acetotolerans, Acetobacter pasteurianus, Agrobacterium larrymoorei, Stenotrophomonas maltophilia, Xanthomonas sacchari, Saccharomyces unclassified, and Alternaria unclassified were identified as the predominant microorganisms during the acetic acid fermentation phase. Further investigation revealed that pH, moisture content, vinegar pei temperature, and non-volatile acids were the primary drivers of microbial succession. Additionally, a detailed metabolic network of flavor compounds in closed solid-state vinegar was successfully constructed. This research not only deepens our comprehension of the complex interplay between microbial communities and flavor quality but also provides essential insights for refining fermentation processes and improving flavor profiles in industrial-scale closed solid-state vinegar production systems.