Analysis of fungal community succession during high-temperature Daqu fermentation process based on Illumina MiSeq high-throughput sequencing technology

In this study, the succession rule of fungal community during high-temperature Daqu fermentation was studied by Illumina MiSeq sequencing technology. The α-diversity analysis showed that the richness and diversity of the fungal community increased first and then decreased during high- temperature Daqu fermentation, and the species number (369.16) and Simpson index (0.75) reached the highest at the time of the second Fanqu, and were highly significantly higher than that at the time of Chaiqu (P<0.01). The dominant fungal genera during Daqu fermentation included Thermoascus, Thermomyces, Aspergillus, Rasamsonia, and Byssochlamys. The β diversity analysis confirmed highly significant changes in fungal community structure during fermentation. Linear discriminant analysis effect size (LEfSe) analysis showed that different fermentation stages presented characteristic dominant bacteria, and Phialosimplex, Thermoascus and Thermomyces could be biomarkers of the first Fanqu, second Fanqu and Chaiqu stages, respectively. Correlation analysis showed that changes in fungal community structure might be closely related to inter-species interactions. These findings laid foundation for future optimization of the Daqu fermentation process and improvement of product quality.