基于酶学特性筛选大曲来源芽孢杆菌用于强化酿酒

通过分析来源于清香型、浓香型和酱香型大曲的105 株芽孢杆菌的产淀粉酶和蛋白酶的能力，优选出1 株地衣芽孢杆菌（Bacillus licheniformis）B.L-1和1 株枯草芽孢杆菌（B. subtilis）B.S-1，将其分别应用于清香型白酒酿造中，探究强化接种微生物对发酵的影响。发酵结束后，在酒醅中共检测到挥发性代谢产物38 种，通过多元统计分析，在强化B.L-1组和B.S-1组中分别筛选出差异代谢物21 个和11 个（VIP＞1；P＜0.05），其中4-乙基-2-甲氧基苯酚、辛酸乙酯、3-甲基丁酸乙酯和四甲基吡嗪在2 组强化中均为差异代谢物，含量显著升高。结果表明，用酶学特性进行菌株筛选能够快速有效地获得特定功能菌株，由此获得的菌株进行强化发酵可显著提高酒醅中挥发性风味物质含量。该方法可以有效地为大曲微生物合成群落重塑提供菌种资源。

Screening of Bacillus from Daqu by Enzymatic Characteristics to Enhance the Fermentation of Chinese Baijiu

The α-amylase and protease activities of 105 Bacillus strains isolated from light-flavor, strong-flavor and sauce-flavor Daqu were evaluated. Out of them, B. licheniformis (B.L-1) and B. subtilis (B.S-1) were selected for application in enhanced fermentation of light-flavor Baijiu. The volatile compounds of fermented grains were determined after completion of the fermentation. A total of 38 volatile compounds were identified by headspace solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS). By multivariate statistical analysis, 21 and 11 significantly differential metabolites were identified in the samples fermented with B.L-1 and B.S-1, respectively (VIP > 1; P < 0.05). 4-Ethyl-2-methoxy-phenol, ethyl octoate, 3-methyl butanoic acid ethyl ester, and tetramethyl-pyrazine were the differential metabolites shared by both enhanced fermentation groups, and their contents significantly increased compared to the control group. The results indicated that enhanced fermentation with the selected Bacillus isolates could remarkably increase the contents of volatile flavor substances in the fermented grains. This study has provided a good way to select potential candidates for the construction of synthetic microbiota in Daqu.