Exploration of the microbial assembly process of Sauce-flavored Baijiu and the core microorganisms responsible for ester production

Ester compounds present in Sauce-flavored Baijiu (SFB) were capable of mitigating the inherent richness of the liquor while improving the clarity of its aromatic profile. Their fermentation process directly determined the quality of the Baijiu and was also a key flavor component. However, the key environmental factors driving microbial succession and the formation of related metabolic products remained unclear. This study found that the core ester-producing microorganisms included three types of bacteria ( Kroppenstedtia, Bacillus , lactic acid bacteria) and three types of fungi ( Fusarium, Saccharomyces cerevisiae, Basidiomyces deformis ). Interestingly, in terms of community construction, bacteria are driven by deterministic processes such as homogeneous selection (βNTI ≥ 2), while fungi are mainly driven by random processes (βNTI < 2), indicating that bacteria are more sensitive to environmental factors. Redundancy analysis indicated that pH value, reducing sugar and alcohol content were the main driving factors of the community structure. In addition, we screened out a strain of Limosilactobacillus fermentum , whose ester composition (e.g., ethyl palmitate, ethyl acetate, ethyl lactate, diethyl succinate) was similar to the distribution of esters in the late stage of cellar fermentation. Such discoveries offer theoretical foundations and technical direction for ensuring stable quality in SFB production. • Seven esters including ethyl acetate account for 95% of total pit esters. • Seven core microorganisms associated with ester production were identified. • It reveals the random and deterministic processes of microbial distribution. • The pH, reducing sugar and alcohol content are the main influencing factors. • Screen the strains whose products highly overlap with the esters in the cellar.