In order to provide valuable information on the current status of research and the hot topics in the field of Baijiu pit mud, a comprehensive bibliometric visual analysis was carried out on 522 pieces of Chinese literature and 112 pieces of English literature in the Web of Science Core Collection (WOSCC) and China National Knowledge Infrastructure (CNKI) databases published from 1980 to 2021. Knowledge graph analysis from the perspectives of annual publication volume, authors and their institutions, highly cited articles and keywords was conducted to summarize recent progress and to predict future trends in this field. Research on Baijiu pit mud is of great significance for the high-quality development of the Baijiu industry and Baijiu quality improvement. The amount of research literature in the field of Baijiu pit mud has shown a trend of fluctuating growth over the past one decade, but it has not yet reached a mature stage, which still has broad development prospects. Chinese scholars are the main force in the field of Baijiu pit mud research. The literature published by the major contributors to this field such as Zhang Wenxue, Tang Yuming, Zhou Rongqing, Wu Chongde, and Xu Yan has a great influence and high academic value. The major institutions that have researched Baijiu pit mud include Sichuan University, Sichuan University of Science Engineering, and Jiangnan University. The research hotspots mainly focus on microbial communities, artificial pit mud, organic acids, butyric acid bacteria, functional bacteria, and so on. The information presented in this paper can help researchers in understanding the current trends and future directions in Baijiu pit mud research and in conducting scientific research and academic exchanges.

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.