Abstract: In this study, metagenomics and metabolomics were combined to systematically analyze the effect of seasonal variation on microbial community succession and volatile compounds during the fermentation of Shanxi aged vinegar Daqu. The results indicated that spring Daqu exhibited the highest liquefying, saccharifying, and esterifying power, and protease activity, while pyrazines were more abundant in summer and autumn Daqu than in spring Daqu. In different seasons, the composition of the dominant microflora varied across various fermentation and storage stages from the first day of fermentation to Daqu stored for 3 months. Correlation analysis revealed that Saccharopolyspora, Klebsiella, Leuconostoc, Thermoactinomyces, Rhizopus, Lichtheimia, Syncephalastrum, Apophysomyces, Aspergillus and Mucor were closely related to the liquefying, saccharifying, fermenting and esterifying power and protease activity of Daqu; Bacillus and Lichtheimia showed significant positive correlations with pyrazine compounds. This study lays a theoretical foundation for enhancing the quality of vinegar Daqu.

Key words: Daqu, production season, metagenomics, microorganism, physicochemical properties, volatile compound, correlation analysis