Promoting microbial community succession and improving the content of esters and aromatic compounds in strong-flavor Daqu via bioaugmentation inoculation

Abstract

Daqu, an indispensable starter, significantly affects the quality and yield of Chinese baijiu. The microbial community, physicochemical properties, and volatile components of traditional Daqu (TD) and fortified Daqu (FD) were analyzed and compared. The bioturbation effect of inoculation with Bacillus subtilis, Staphylococcus epidermidis, and Millerozyma farinosa on strong-flavor Daqu was discussed. The results indicated a significant decrease in Bacillus and an increase in five bacterial genera (e.g., Weissella and Staphylococcus) and four fungal genera (e.g., Saccharomycopsis and Millerozyma) after bioaugmentation inoculation. The volatile compound content, including esters and aromatic compounds, increased dramatically after bioaugmentation inoculation. The correlation analysis showed that the Weissella, Pediococcus, and Staphylococcus in FD were positively associated with esterification activity. Moreover, PICRUSt2 predicted many enzymes involved in aroma production and ethanol fermentation. Bioaugmentation inoculation promoted microbial community succession and regulated microbial metabolic activity to enhance the flavor characteristics of Daqu.