Multi-omics insights into microbial community and functional expression in medium-temperature Daqu following mung bean substitution

Daqu is a key saccharifying and fermenting starter in Baijiu production. Mung bean Daqu (MBQ) is produced by replacing pea with mung bean in traditional medium-temperature Daqu, yet its functional characteristics remain unclear. This study integrated multi-omics approaches to investigate the effects of mung bean substitution on microbial community and functional expression in medium-temperature Daqu. MBQ retained dominant microbial genera, while Saccharopolyspora, Thermoactinomyces, Paecilomyces, and Aspergillus were identified as biomarkers. Following mung bean substitution, the predominant downregulation of α-amylase and significant upregulation of glucoamylase and β-fructofuranosidase reshaped starch degradation and promoted fermentable sugar release, while pyruvate conversion favored ethanol formation over lactate and acetyl-CoA formation. These changes were consistent with 25.38% and 117.78% increases in saccharifying and fermenting powers, respectively, along with lower liquefying in MBQ. These findings provide new insight into raw material optimization for Daqu production.