清香型白酒发酵过程中酵母群落结构及其与尿素代谢的关系

Dynamic profile of yeast community associated with urea metabolism in Chinese light-aroma liquor fermentation

【目的】探索清香型白酒发酵过程中酵母群落结构及演变,分析潜在的关键尿素代谢酵母及其环境调控因素,为降低发酵过程中氨基甲酸乙酯的含量提供理论依据。【方法】通过相关性分析明确发酵过程中氨基甲酸乙酯主要前体物质及其代谢微生物类群,利用高通量测序技术解析酵母群落结构组成,并结合偏最小二乘回归分析寻找潜在的关键尿素代谢酵母。采用冗余分析评价发酵过程中环境因素对酵母群落结构的影响。【结果】尿素是清香型白酒发酵过程中氨基甲酸乙酯的主要前体物质,酵母是尿素代谢的主要微生物。高通量测序结果显示,在97%的相似度下进行操作分类单元聚类后,共鉴定出22个酵母种。其中,嗜高压有孢汉生酵母(Hanseniaspora osmophila)、发酵毕赤酵母(Pichia fermentans)和酿酒酵母(Saccharomyces cerevisiae)与尿素合成存在正相关性,库德毕赤酵母(Pichia kudriavzevii)与尿素降解存在正相关性。酒醅含水量、p H、乙醇和精氨酸是影响发酵过程中酵母群落演替的重要环境因素。【结论】环境因素影响潜在的关键尿素代谢酵母,为降低发酵过程中尿素与氨基甲酸乙酯含量提供理论依据。

[Objective] This study was to explore the structure and dynamic of yeast community, and to analyze the potential key yeast species associated with urea metabolism and its regulation by environmental factors. It could provide potential clues for reducing ethyl carbamate in Chinese light-aroma liquor fermentation process. [Methods] The main precursor and microbial groups were identified by correlation analysis, and yeast community was revealed by high-throughput sequencing. Besides, the potential key species related with the urea metabolism were predicted by partial least squares regression. In addition, the effect of environmental factors on yeast community was analyzed by redundancy analysis. [Results] Urea was identified as the main precursor, and was associated with yeast population in Chinese light-aroma liquor fermentation. A total of 22 yeast species was identified by high-throughput sequencing at 97% sequence similarity. Hanseniaspora osmophila, Pichia fermentans and Saccharomyces cerevisiae were positively associated with urea formation, while Pichia kudriavzevii was positively associated with urea degradation. In addition, moisture, p H, ethanol and arginine were important environmental factors which associated with yeast community during liquor fermentation process. [Conclusion] Environmental factors could influence the potential key yeast species, which could provide strategies to decrease urea and ethyl carbamate in Chinese light-aroma liquor fermentation.