Assembly mechanisms and function features of prokaryotic communities in artificial pit mud related to soil type and inoculum

Abstract

The prokaryotic community of artificial pit mud (APM), which is manufactured using fresh soil as the raw material, pit mud (PM) as the inoculum, and yellow water (YW) as the nutrient source, significantly affect the quality of strong-flavor Baijiu. Here, the APM assembly mechanisms and function features under the different treatments were explored by microcosmic experiments. The results revealed that the soil type could directly influence the APM physicochemical properties, and the inoculum mainly affected the typical organic acids. Microbial analyses revealed that the influence of soil type (22.69 %) and inoculum (20.60 %) on the APM prokaryotic community was greater than that of YW nutrient (7.50 %). Among them, black soil was more conducive to the stability, compactness, and modularization tendency of the co-occurrence network, compared to loess soil. Assembly model showed that most APMs predominantly relied on the stochastic process (|βNTI| ≤ 2), and black soil might facilitate the balance of the stochastic and deterministic processes. Metabolism annotation unveiled that new PM inoculum stimulated lipopolysaccharide biosynthesis, sphingolipid metabolism and lysosome, affecting the stability of APM individual microorganism compared to old PM inoculum. The environmental adaptation revealed that old PM inoculum, black soil, and YW nutrient contributed to the broader environmental thresholds, enhancing the APM adaptability to diverse feedstock environments. These findings could provide valuable insights into standardizing APM in the future.