Abstract: To investigate the impact of altitude gradients on the composition and distribution patterns of fungal communities in the brewing environment of Jiangxiangxing Baijiu (encompassing air and various surfaces, including production utensils, workshop floors, and walls), this study examined the brewing environment and fermented grains from seven different altitude levels (Groups A–G) within the same production facility in the Chishui River basin. Using Illumina MiSeq amplicon high-throughput sequencing combined with multivariate statistical analysis, we analyzed the effects of altitude on the community composition, distribution, and assembly processes of fungal communities in the brewing environment. The results demonstrated significant differences among groups in the Chao1 and Shannon indices (P < 0.05) but not in the ACE or Simpson indices. Additionally, altitude had no consistent effect on the niche breadth of fungal species and was non- linearly associated with the operational taxonomic unit (OTU) richness and Shannon index. Ascomycota was the dominant phylum in the brewing environment, with Pichia, Zygosaccharomyces, and Monascus identified as the core dominant fungal genera. The relative abundance of Lodderomyces was negatively correlated with altitude (P < 0.05), suggesting its potential as a microbial biomarker for the influence of altitude gradients on the brewing environment. Neutral model analysis revealed that deterministic processes (environmental selection) dominated the assembly of fungal communities, with altitude as a key environmental factor driving β-diversity differentiation among communities. This study uncovers the association between geographical altitude and the microecology of Jiangxiangxing Baijiu brewing, thereby providing data support for the exploration of microbial strain resources and process optimization in Jiangxiangxing Baijiu production regions.

Key words: Jiangxiangxing Baijiu; brewing environment; altitude gradient; fungal diversity; niche distribution; community assembly