Abstract: In order to uncover the influence of various physicochemical indicators on the microbial community structure in Chinese liquor fermentation pit muds, the difference in the physicochemical properties of pit muds of different ages and their correlation with the prokaryotic community structure were studied. The results showed that the contents of moisture, pH, ammonium nitrogen, available phosphorus and available potassium in 20-year-old pit bottom and wall muds were significantly higher than those in the 2-year-old pit muds, while the calcium content was significantly lower than that in the 2-year-old pit muds. However, there was no significant difference in any physicochemical indexes except moisture and humus contents between the 30-year-old pit bottom and wall muds and those aged two years. The correlation analysis indicated that moisture content, pH and ammonium nitrogen content had the most prominent effect on the microbial flora, which were significantly negatively correlated with Lactobacillus (P < 0.01), and significantly positively correlated with six bacterial genera including Aminobacterium, Syntrophomonas and Sedimentibacter (P < 0.05). The various microbial floras in the young pit muds interacted with each other during long-term repeated fermentation; some microorganisms gradually became dominant and the microflora structure finally reached a dynamic balance, resulting in the formation of high-quality pit mud. The results of this study will provide theoretical support for the quality maintenance of pit mud and the production of high-quality pit mud.

Key words: prokaryotic community; pit mud; physicochemical indexes; Pearson correlation; high-throughput sequencing