High-throughput Sequencing Analysis of Diversity and Spatial Heterogeneity of Fungal Community in Pit Muds of Different Ages for Baijiu Production

The fungal community structure, the relationship between fungal flora and physicochemical factors, and the prediction of fungal function in pit muds from different spatial positions of 10- and 50-year-old cellars at Jinhui liquor Co. Ltd. were studied by using Illumina NovaSeq high-throughput sequencing, redundancy analysis and Fungi Functional Guild (FUNGuild). The results showed that the fungal diversity and richness of the 10-year-old pit mud decreased with increasing depth; the fungal diversity of the 50-year-old pit mud showed an overall increasing trend, while the fungal richness initially decrease and then increased. Moreover, for the 10-year-old pit, the fungal diversity and richness of the upper layer of the pit wall were significantly higher than those of the other positions (P < 0.05), while for the 50-year-old cellar, the fungal diversity and richness of the bottom layer were significantly higher than those of the other locations (P < 0.05). The fungal diversity and richness were significantly higher in the wall of the 10-year-old cellar than the 50-year-old cellar (P < 0.05), but were significantly higher in the bottom of the 50-year-old cellar than the 10-year-old cellar (P < 0.05). A total of 21 fungal phyla and 520 genera were detected in all pit mud samples, the relative abundance of four dominant phyla (Ascomycota, Basidiomycota, Mortierellomycota and Rozellomycota) and most dominant genera such as Aspergillus and Kazachstania showed significant changes among pit ages and spatial locations (P < 0.05). Fusarium, Aspergillus, Saccharomyces and Monascus were positively correlated with the contents of water, humus, K+ and Ca2+, while Cladosporium and Vishniacozyma were positively correlated with pH. Seven nutritional modes of fungi were observed, mainly including saprophytic and pathological-saprophytic-symbiotic nutritional modes, and four single and seven mixed functional groups were determined. This study provides a theoretical basis for clarifying the structure and spatial distribution of fungal community in Jinhui Baijiu pit mud.