Distinct succession of abundant and rare fungi in fermented grains during Chinese strong-flavor liquor fermentation

The traditional spontaneous solid-state fermentation of Chinese strong-flavor liquor is a complex and unique ecosystem with few abundant and many rare taxa. However, the rare and keystone taxa of fermented grains (FGs) during liquor fermentation are still not completely clear. In this study, we used Illumina MiSeq sequencing to investigate the succession of abundant and rare fungi during Chinese strong-flavor liquor fermentation. The results showed that the changes in alpha and beta diversity of abundant and rare taxa were significantly different during liquor fermentation. There were 9 abundant fungal genera and 176 rare fungal genera during liquor fermentation, and the dominant fungal genera changed from Thermoascus within 0 day’ FG to Torulaspora and Saccharomyces within others. Co-occurrence network analysis identified 14 keystone taxa during liquor fermentation, and displayed that positive correlations (95.82%) was dominate in fungal network. Moreover, environmental fungi (Daqu, pit mud and air fungi) and FG characteristics (mainly reducing sugar) together drove the succession of the abundant and rare fungi during Chinese strong-flavor liquor fermentation. Our study provides new insights for understanding the dynamic succession of fungal communities during liquor fermentation and improving the quality and controllability in liquor production.