Active Levilactobacillus namurensis promotes the formation of characteristic aroma in Xiangxi radish paocai, through amino acid metabolism: Based on metatranscriptomics and metabolomics analysis

Authors:
  • YZYingjun Zhou
    Yingjun Zhou
  • SLShimei Liu
    Shimei Liu
  • TCTao Chen
    Tao Chen
  • XLXiaochun Li
    Xiaochun Li
  • LYLi Yan
    Li Yan
  • ZZZuohua Zhu
    Zuohua Zhu
  • YPYuande Peng
    Yuande Peng
  • XSXiaojun Su
    Xiaojun Su
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Abstract
Xiangxi radish paocai is a regionally distinctive fermented vegetable whose characteristic aroma depends on microbial succession during brine fermentation, but the active microbial and metabolic basis of this flavor remains unclear. Here, metatranscriptomics, metabolomics, and HS-SPME-GC-Q-TOF-MS were integrated to characterize flavor formation during Xiangxi radish paocai fermentation. Organic acid accumulation, especially lactic and acetic acid, together with free sugar depletion, represented the main environmental pressure associated with microbial succession (R2 > 0.79). This shift favored acid-tolerant bacteria, with active Levilactobacillus namurensis becoming dominant and increasing from 41.01% to 47.18%. HS-SPME-GC-Q-TOF-MS identified 24 key aroma-active compounds, including the novel meat flavour compound 2-pentylpyridine, which showed a relative odour activity value as high as 2700.02. Correlation analysis further showed that L. namurensis abundance was strongly correlated with 16 characteristic aroma compounds, likely linked to precursor metabolism involving serine, alanine, glycine and histidine. These findings provide a mechanistic basis for understanding flavor development in Xiangxi radish paocai and support for optimization of the fermentation process.

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