Abstract:[Objective] This study was designed to elucidate the microbial community succession dynamics of rice straw and high-temperature Daqu at distinct stages of fermentation, investigate the associations between differential metabolites and dominant microorganisms, and preliminarily predict the sources and contribution of microorganisms in high-temperature Daqu. [Method] High-throughput sequencing combined with liquid chromatography-mass spectrometry (LC-MS) was used to analyze the variation patterns of microbial communities and metabolites during the fermentation of high-temperature Daqu. [Result] Pantoea and Pseudomonas were the dominant bacterial genera, while the dominant fungal genera were Mrakia and Nigrospora in new rice straw (XC). For mother rice straw (MC), Bacillus and Saccharopolyspora were identified as the dominant bacterial genera. At various fermentation stages, the dominant fungal genera were Thermomyces and Aspergillus, whereas the dominant bacterial genera were Saccharopolyspora, Acinetobacter, Bacillus, and Thermoactinomyces. LEfSe revealed no significant differences in the dominant bacterial taxa between high-temperature Daqu and rice straw. In contrast, a total of six differential fungal taxa were collectively identified through co-analysis. Among them, Alfaria and Myriococcum were recognized as the marker fungal specific to rice straw, while Pichia、Saccharomyces、Monascus, and Kodamaea were the representative marker fungal in high-temperature Daqu. Source Tracker-based source tracking analysis indicated that the bacterial contribution of rice straw to high-temperature Daqu was negligible across different stages, whereas the fungal contribution varied among stages. Notably, the second-turn rice straw (EFC) exerted the highest fungal contribution to the detached Daqu (CQQ). Metabolomic profiling revealed 197 differential metabolites between rice straw and high-temperature Daqu. The correlation network between these differential metabolites and dominant microorganisms underpinned the fundamental biological regulatory mechanisms governing the fermentation process. [Conclusion] This study establishes a foundation for subsequent investigations into the fermentation mechanism of high-temperature Daqu and for enhancing the controllability of traditional fermentation processes.
