[Effects of knockout ECM25/YJL201W gene in brewing yeast on beer flavor stability].
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 ll degrees C and 28 degrees C, 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.
Zhang
Yixin
Y
The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China.
Li
Qi
Q
Shen
Wei
W
Xie
Yan
Y
Gu
Guoxian
G
D001515:Beer / Q000382:microbiology*; D005285:Fermentation; D055786:Gene Knockout Techniques; D005978:Glutathione / Q000378:metabolism*; D011995:Recombination, Genetic; D012440:Saccharomyces / Q000235:genetics*
D005978:Glutathione