Analysis and application of microbiota in fermentation pit muds used for Chinese strong-flavor liquor production.

Chinese strong-flavor liquor (CSFL), the primary type of Chinese liquor in terms of both production and sales, is produced through complex fermentation in pits covered with fermentation pit mud (FPM). FPM, which contains complex microbiota, is crucial for the quality of CSFL. Therefore, monitoring the quality of FPM and acquiring high-quality FPM are important for CSFL manufacturers. However, this requires further study because the relationship between the microbiota and FPM quality remains largely unclear. In this study, high- and low-quality FPM samples were selected based on two-year production data, and the microbiota were sequenced with the HiSeq2500 PE250 platform. Compared with low-quality FPMs, high-quality FPMs exhibited more similar microbiota, and a higher abundance of Euryarchaeota and Firmicutes. Furthermore, the relative abundance of five abundant genera including Methanobacterium, Methanosaeta, Clostridium, Syntrophomonas and Aminobacterium, were positively correlated with the quality of FPM and could construct a synergistic network helpful for inhabiting FPM and improving the quality of CSFL. At the species level, the abundance of Clostridium kluyveri and the new biomarker Syntrophomonas wolfei increased in high-quality FPMs and could be rapidly detected using polymerase chain reaction (PCR). By applying functional microbes and knowledge of the microbial ecosystem, artificial FPM was successfully incubated within 50 days, and the yield of high-quality CSFL had an increase of 43.72% compared to that produced with mature FPM. This study provides new insights into further understanding of the microbial ecosystem of FPM and will be useful for producing artificial FPM, as well as for monitoring and improving the quality of FPM used for CSFL production.