Illuminating the Patterns of Fungal Community Succession, Physicochemical Properties, Volatiles and Their Relationships in Fermented Grains for the Production of Chinese Strong-Flavor Baijiu

Fermented grains (FGs) for Chinese strong-flavor Baijiu (CSFB) serve as both microbial habitats and flavor sources, yet the correlations among fungal communities, physicochemical properties, and volatiles during long-term fermentation remain insufficiently understood. To address this gap, this study employed Illumina HiSeq high-throughput sequencing, physicochemical analysis, and GC-MS for systematic investigation. Fermentation was divided into early, middle, and late stages based on FGs' physicochemical dynamics and eukaryotic microbial diversity. A total of 9 fungal phyla and 195 genera were detected, with 12 dominant genera (e.g., <i>Thermoascus</i>, <i>Aspergillus</i>, <i>Kazachstania</i>). Forty-seven volatiles were identified, showing increasing diversity and richness. Redundancy Analysis revealed total acids exerted the most significant effect on dominant fungal succession, while network analysis screened 10 key genera (e.g., <i>Mortierella</i>, <i>Trichoderma</i>) pivotal for community structure. Additionally, <i>Trichoderma</i>, <i>Fusarium</i> and other genera correlated with important flavors like 1-butanol and 1-hexanol. This study clarifies the complex interactions in FGs, provides theoretical support for CSFB quality improvement via biofortification or environmental control, and offers a reference for revealing the ecological mechanisms underlying FG microbial community assembly.