啤酒酵母ECM25YJL201W基因敲除对啤酒风味稳定性的影响.doc

啤酒酵母ECM25/YJL201W基因敲除对啤酒风味稳定性的影响 张一心, 李崎, 沈微, 谢焱, 顾国贤 江南大学工业生物技术教育部重点实验室, 无锡 214122 摘 要: 以pUG6为模板, 设计含有与25基因两侧序列同源的长引物, 构建了带有基因(kan)破坏盒, 转化啤酒酵母G-03, 获得一株G-03/a转化菌, , 测序结果证实ECM25基因敲除是成功的。有氧条件下11oCoC培养时转化菌G-03/a的胞外GSH)分泌量比高21.4, 与原菌株相比, 转化菌G-03/a发酵液GSH含量分别提高32.1%和13.8%, 发酵液SI系数高7.7%5.3%, 成品啤酒RSV值高45.0%。, 与原菌株相比, 转化菌G-03/a发酵液中GSH含量提高34.0%。转化菌G-03/a与G-03所酿制成品啤酒的常规指标没有显著差别。表明G-03/a是一株具有抗老化能力的优良啤酒酵母, 能够提高啤酒的风味稳定性。: 啤酒酵母, 基因敲除, 25, 谷胱甘肽分泌啤酒风味稳定性Effects of Knockout ECM25/YJL201W Gene in Brewing Yeast on Beer Flavor Stability Yixin Zhang, Qi Li, Wei Shen, Yan Xie, and Guoxian Gu The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China Abstract: The ECM25 deletion mutant of industrial brewing yeast, G03/a, was constructed by replacing the ECM25 gene with the kanMX gene. The transformant was verified to be genetically stable. The PCR analysis showed that ECM25 gene in the G-03/a was deleted. Under aerobic conditions of 11oC and 28oC, compared with the host strain G-03, the excretive glutathione concentration of G-03/a increased by 21.4% and 14.7%, respectively. Strains G-03 and G-03/a were inoculated in flasks and cultivated continuously for 4 generations. Compared with the host strain G-03, the glutathione concentration in the main fermentation broth and final beer of strain G-03/a increased by 32.1% and 13.8%, the stability index (SI) increased by 7.7% and 5.3%, respectively, and the flavor resistance staling value (RSV value) in final beer increased by 45.0%. During EBC fermentation, the glutathione concentration in the main fermentation broth of strain G-03/a increased by 34.0%, compared with the host strain G-03. Furthermore, no significant difference in routine fermentation parameters was found. The strain G-03/a is proved to be an excellent anti-staling brewing yeast to improve beer flavor stability. Keywords: brewing yeast, gene knockout, ECM25, glutathi