Exploring the differential characteristics of Nongxiangxing Baijiu pit mud from multiple perspectives: A case study of fermentation pits in workshops with varied alcohol yields

The quality of pit mud (PM) and its rich microbial community are closely related to the quality of Chinese Nongxiangxing Baijiu. This study selected PM samples from two workshops exhibiting differing alcohol yields as the research object and conducted systematic experimental investigations. The PM from Workshop 4, which has a higher alcohol yield, is richer in available potassium (AK) and metal elements. Between them, AK exhibits a positive correlation with Aspergillus and Monascus . PM from Workshop 4 exhibited a greater number of unique OTUs compared to Workshop 2. The dominant bacterial genera showed minimal differences between the two workshops, whereas distinct compositional variations were observed among fungal genera. For instance, notable differences in relative abundance were observed for the fungal genera Aspergillus , Monascus , Candida , Saccharomycopsis , and Wickerhamomyces were obviously different between the PM from the two workshops. Additionally, differential biomarkers identified between the PM samples from the two workshops were predominantly composed of fungal microorganisms. Finally, non-targeted metabolomics showed that Sphingolipid metabolism, Starch and sucrose metabolism, Streptomycin biosynthesis, Retinol metabolism, Glycerophospholipid metabolism, Isoflavonoid biosynthesis, and Citrate cycle (TCA cycle) were the key metabolic pathways for the differential metabolites between the two groups of PM. • PM differences were analyzed in workshops with different alcohol yields • Fungal communities in PM of the two workshops differed significantly • The physicochemical indices affecting the dominant microbial genera were identified • Differential biomarkers and metabolites were identified