Geographic convergence of bacterial communities in pit mud: A shared assembly mechanism driven by pH-mediated core...

Pit mud, a typical substance used for Baijiu fermentation, lacks cross-regional studies, hindering the development of standardized regulatory strategies. This study integrated large-scale data from three major Baijiu-producing regions to elucidate the bacterial characteristics of pit mud. Significant differences in bacterial communities were observed, yet geographical impact was minimal (R² = 0.0475). Differences were primarily driven by richness differences (73.39 %) rather than species replacement, with ten key families dominating the structure across regions. Three regional bacterial networks showed high convergence, characterized by abundant positive correlations. Notably, Lactobacillaceae, the most abundant family, was independent in networks, while Oscillospiraceae, Clostridiaceae, and Dysgonomonadaceae drove succession through interfamilial interactions. Heterogeneous selection dominated bacterial assembly, with pH identified as the core factor. As pH rose from 5.0 to 7.0, Lactobacillaceae sharply declined, while Oscillospiraceae, Clostridiaceae, and Dysgonomonadaceae significantly proliferated, which was a cross-regional pattern. These findings advance microbial biogeography in the Baijiu industry.