在白酒的酿造生产过程中，酸度是一项重要的酿造指标。酸胁迫对白酒生产有着重要的影响，主要体现在随着发酵的进行对曲药中的微生物群落结构进行重塑等方面。该研究在实验室构建白酒固态发酵模型，分别设置低、中、高三种酸度条件，探究白酒酿造过程中的酸胁迫对糟醅微生物群落结构的影响。结果表明：在酸度的影响下，产酸细菌和耐酸性强的芽孢杆菌相对丰度增加，耐酸性差的细菌相对丰度降低；真菌门中子囊菌门占绝对优势，窖内溶氧的降低和发酵起始酸度的增加使得真菌属都呈先增后降的趋势。通过分析不同糟醅中各类微生物的数量发现细菌和乳酸菌随酸度的增加而下降；己酸菌在酸度为15 mmol/100 g时数目最多；酵母数量随酸度增加而下降。对糟醅进行理化性质分析，结果显示随着酸度的增加，糟醅中淀粉含量越多；在高酸度下，糟醅中乙醇含量低。该研究分析了酸度对糟醅微生物群落结构的重塑过程，分析了酿造有益菌在不同酸度下的生长情况，能保证有益微生物在良好的条件下生长繁殖，为白酒酿造提供了科学理论指导。

Acidity is an important parameter in the brewing of Daqu baijiu. Acid stress plays a key role in the production of baijiu, as it reshapes the microbial community structure of the fermentation starter during the brewing process. To study the impact of acid stress on microbial community structure in fermenting grains during baijiu brewing, a solid-state model of baijiu brewing was constructed with three different acidity levels (low, medium, and high). The results showed that increasing acidity increased the relative abundance of acidogenic bacteria and acid-tolerant Bacillus bacteria, and decreased the relative abundance of acid-intolerant microbes. The dominant microbes were members of the Ascomycota fungal phylum, and their numbers initially increased with decreases in dissolved oxygen and increases in acidity in the mash before decreasing. According to the microbe numbers in the fermenting grains, increasing acidity decreased the number of aerobic bacteria and lactic acid bacteria. Caproic acid-producing bacteria were the most abundant when the acidity level was 15 mmol/100 g. Furthermore, the yeast population decreased with increasing acidity. The physicochemical analysis of fermenting grains showed that increasing acidity increased starch content in the grains and that high acidity resulted in low ethanol content. Overall, by analyzing how acidity reshapes the microbial bacterial structure of fermenting grains and the growth of desirable microbes under different levels of acidity, this study has identified the optimal conditions for the proliferation of desirable microbes and thereby provides scientific guidelines for the brewing of baijiu.

四川江口醇隆鼎酒业有限公司院士（专家）工作站项目（HX2022065）；四川轻化工大学研究生创新基金项目（y2021045）