Abstract: Based on the core endogenous functional strains of high-temperature Daqu, a synthetic microbial community was constructed for solid-state fermentation. Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was employed to analyze the impact of temperature stress on the metabolism of volatile compounds in the synthetic microbial community. Metatranscriptomics was employed to study the temperature response mechanisms of key metabolic genes in the microbial community under thermal stress and to elucidate the dynamic regulation patterns of flavor-related genes in response to temperature variations. The findings demonstrated that fermentation temperature significantly regulated pyrazines, phenols, alcohols, and other compounds in the synthetic community. Under high-temperature stress, the microbial community redistributed metabolic resources through preserving core functions while eliminating redundant consumption. During fermentation at 40 ℃, the synergistic interactions of genomes in the synthetic community were more pronounced, and the expression profiles of the core functional genes were significantly shifted. In addition, the metabolic capacity for flavor compounds was enhanced and the expressions of the gudB and sucC genes were notably upregulated. Under thermal stress at 50 ℃, the community activated heat-shock response mechanisms, thereby triggering its functional redirection and dramatic upregulation of the pgm and tpiA genes. Among the metabolic pathways regulating differential volatile compounds, the biosynthesis of flavor substances exhibited a significant correlation with amino acid metabolism pathways, particularly the branched-chain amino acid and aromatic amino acid metabolism pathways. This study provides theoretical support for optimizing the temperature-controlled Qu-making process, enhancing the controllability of solid-state fermentation, and developing artificial microbial agents.

Key words: synthetic microbial communities; metatranscriptomics; flavor compounds; temperature stress; metabolic mechanisms