Mining the factors driving the succession of microbial community in pit mud used for the production of Nongxiangxing baijiu

The pit mud (PM) provides a unique anaerobic environment for the fermentation of Nongxiangxing baijiu. Previous research has indicated a close relationship between PM quality and cellar age. However, the molecular basis of microbial dynamics and associated functions of microbial community remain unclear. Here, we explored the microbial communities of PM samples from three different locations with various temporal gradients. Based on the maturity time of PM, all samples were divided into two stages, P1 (cellar age<20) and P2 (cellar age≥20), and 30 microbial genera were identified as biomarkers. Mantel test demonstrated a significant correlation between acetic acid and biomarkers in P1 stage, whereas in P2 stage, hexanoic acid and lactic acid were significantly correlated with the bacterial community. Furthermore, random forest analysis suggested that the main driving factors of the bacterial community succession were NH4+–N, available phosphorus, and moisture, while the fungal community succession were available phosphorus and acetic acid. PICRUSt2 analysis demonstrated that the bacteria in aged PM had a higher potential to synthesize butyric acid compared with the new pit mud. Results presented in this study may provide a basis for the future artificial adjustment of PM quality.