Unraveling the mycobiota of Daqu at the species level using metabarcoding of full-length ITS sequences

Daqu, the starter used in Baijiu making process, is produced by spontaneous solid-state fermentation and contains numerous microbes and enzymes, significantly influencing the yield and flavour profile of Baijiu. In this study, we employed a full-length ITS metabarcoding approach using the PacBio sequencing technology to investigate the fungal diversity in 296 samples of low- (LTD), medium- (MTD) and high-temperature Daqu (HTD) collected from 10 provinces in China. In total, we identified 86 species or species groups in the fungal communities of Daqu. The fungal communities of the three types of Daqu were significantly different and the differences were also associated with their geographical origins. <i>Ascoideales</i> (relative abundance 21.04%), <i>Pichiales</i> (15.38%), <i>Mucorales</i> (39.54%) and <i>Eurotiales</i> (19.96%) totally accounted for 95.92% of the fungal community of the Daqu samples. The former two were significantly enriched in the LTD samples and the latter two in the MTD and HTD samples, respectively. We also identified the distinct fungal species that showed differential enrichment within each Daqu type as well as among samples of the same type originating from different regions. These findings offer a deeper insight into the fungal communities associated with various Daqu types and their geographical origins at the species level.