大曲中产阿魏酸酯酶菌株的筛选及其特性分析

Screening of ferulic acid esterase-producing strains in Daqu and analysis of their characteristics

中文关键词:  大曲  阿魏酸酯酶  屎球肠菌  安全性评价  耐受性

英文关键词:Daqu  ferulic acid esterase  Enterococcus faecium  safety evaluation  tolerance

中文摘要:

      目的 从浓香型白酒大曲中分离筛选出一株产阿魏酸酯酶的菌株。方法 将大曲样品中筛选出的11株菌进行划线纯化培养, 进一步挑选出产阿魏酸酯酶酶活较强的菌株并鉴定, 分析其安全性及生物学特性, 最后对发酵产酶条件进行优化。结果 得到一株产阿魏酸酯酶酶活较强的菌株为L-7, 经鉴定为屎肠球菌(Enterococcus faecium)。经毒力基因检测、有害代谢产物实验结果均为阴性; 生物学特性研究实验结果为: 在16 h时生物量达到最大, 耐最低pH为4, 最高为11, NaCl质量分数为8%的条件下仍能生长, 耐受最高的乙醇体积分数为13%; 具有较好的安全性且有耐乙醇、耐盐、广泛的pH耐受性等优良性能。通过发酵产酶条件优化, 该菌株产阿魏酸酯酶最佳发酵条件为: 接种量为6%体积分数、培养温度32℃、转速160 r/min、培养时间96 h; 此时该菌株产阿魏酸酯酶的酶活为(44.68±0.05) U/L, 较优化前提高了57.05%。结论 本研究结果可为产阿魏酸酯酶的菌株筛选提供参考, 且筛选所得屎肠球菌在提高浓香型白酒及其他发酵食品中阿魏酸含量及风味具有应用潜力。

英文摘要:

      Objective To isolate and screen a strain producing ferulic acid esterase from Luzhou-flavor liquor Daqu. Methods The 11 strains screened from Daqu samples were subjected to streaking purification culture, and the strains with strong ferulic acid esterase activity were further selected and identified, and their safety and biological characteristics were analyzed. Finally, the fermentation conditions were optimized. Results A strain with strong ferulic acid esterase activity was obtained as L-7, which was identified as Enterococcus faecium. The results of virulence gene detection and harmful metabolites test were negative. The experimental results of biological characteristics showed that the biomass reached the maximum at 16 h, the lowest pH tolerance was 4 and the highest pH tolerance was 11, and it could still grow under the condition of NaCl mass fraction of 8%, and the highest ethanol volume fraction was 13%. It had good safety and excellent properties such as ethanol resistance, salt resistance and wide pH tolerance. Through the optimization of fermentation conditions, the optimum fermentation conditions for the production of ferulic acid esterase by the strain were as follows: The inoculation amount was 6%, the culture temperature was 32℃, the rotation speed was 160 r/min, and the culture time was 96 h. At this time, the enzyme activity of ferulic acid esterase produced by the strain was (44.68±0.05) U/L, which was 57.05% higher than that before optimization. Conclusion The results of this study can provide a reference for the screening of strains producing ferulic acid esterase, and the screened Enterococcus faecium has application potential in improving the content and flavor of ferulic acid in Luzhou-flavor liquor and other fermented foods.