Fungal community diversity profiles in pit mud samples from Chinese Strong-flavour liquor pit

Abstract Pit mud is a specialized type of fermented soil that is essential for the distillation of Chinese strong-flavour liquor. In this analysis, differences in fungal community structures and physicochemical properties in pit mud samples from different spatial positions within fermentation cellars were analyzed, revealing unique characteristic multidimensional pit mud fungal community profiles. Penicillium fuscoglaucum, Penicillium glandicola, Aotearoamyces nothofagi, Malassezia restricta, Penicillium lanosocoeruleum, Penicillium crustosum, and Aspergillus tonophilus were detected only in pit mud samples from the upper cellar wall, while Alternaria alstroemeriae, Trichosporon insectorum, Fusarium equiseti, Calonectria pseudoreteaudii, Penicillium clavigerum, Penicillium compactum, Ascochyta phacae, Metarhizium frigidum, Alternaria burnsii, Fusarium nurragi, and Didymella keratinophila were present only in the middle cellar wall layer. Additionally, Alternaria zantedeschiae and Ilyonectria cyclaminicola were only present in pit mud samples from the lower cellar wall, while Leptobacillium leptobactrum, Calonectria queenslandica, Aspergillus appendiculatus, and Candida pseudolambica were only detected in samples of pit mud from the cellar bottom. Moisture, pH, PO43-, acetic acid, humus, K+, Mg2+, Ca2+, acetic acid, butyric acid, and caproic acid levels in these different pit mud positions exhibited a rising incremental pattern from the upper wall layer to the bottom layer, whereas lactic acid levels were significantly lower in the bottom pit mud layer relative to these other layers. Moisture, pH, and NH4+-N were identified as the three most significant factors associated with fungal community composition through a redundancy analysis. Overall, these findings may offer a theoretical foundation for future efforts to improve or standardize artificial pit mud.