College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510640, China.
Appl Microbiol Biotechnol. 2013 Oct;97(20):8913-21. doi: 10.1007/s00253-013-5137-x. Epub 2013 Aug 6.
Significant positive correlations between wort fermentability and the assimilation of Lys and His under normal-gravity and high-gravity conditions indicated that Lys and His were the key amino acids for lager yeast during beer brewing. In order to obtain insight into the roles of Lys and His in nitrogen regulation, the influences of Lys, His and their mixture supplementations on the fermentation performance and nitrogen metabolism in lager yeast during high-gravity fermentation were further investigated in the present study. Results showed that Lys and His supplementations improved yeast growth, wort fermentability, ethanol yield and the formation of flavor volatiles. Lys supplementation up-regulated Ssy1p-Ptr3p-Ssy5p (SPS)-regulated genes (LYP1, HIP1, BAP2 and AGP1) dramatically compared to nitrogen catabolite repression (NCR)-sensitive genes (GAP1 and MEP2), whereas His supplementation activated SPS-regulated genes slightly in exponential phase, and repressed NCR-sensitive genes significantly throughout the fermentation. Lys and His supplementations increased the consumption of Glu and Phe, and decreased the consumption of Ser, Trp and Arg. Moreover, Lys and His supplementations exhibited similar effects on the fermentation performance, and were more effective than their mixture supplementation when the same dose was kept. These results demonstrate that both Lys and His are important amino acids for yeast nitrogen metabolism and fermentation performance.
在正常重力和高重力条件下，麦汁可发酵性与赖氨酸和组氨酸同化之间存在显著的正相关关系，这表明赖氨酸和组氨酸是啤酒酿造过程中拉格酵母的关键氨基酸。为了深入了解赖氨酸和组氨酸在氮调控中的作用，本研究进一步研究了赖氨酸、组氨酸及其混合物补充对高浓度麦汁发酵过程中拉格酵母发酵性能和氮代谢的影响。结果表明，赖氨酸和组氨酸的补充提高了酵母生长、麦汁可发酵性、乙醇得率和风味挥发物的形成。与氮分解代谢抑制（NCR）敏感基因（GAP1 和 MEP2）相比，赖氨酸补充显著上调了 Ssy1p-Ptr3p-Ssy5p（SPS）调控基因（LYP1、HIP1、BAP2 和 AGP1）；而组氨酸补充在指数生长期轻微激活 SPS 调控基因，整个发酵过程中显著抑制 NCR 敏感基因。赖氨酸和组氨酸补充增加了 Glu 和 Phe 的消耗，减少了 Ser、Trp 和 Arg 的消耗。此外，赖氨酸和组氨酸补充对发酵性能具有相似的影响，且在保持相同剂量时，其效果优于混合物补充。这些结果表明，赖氨酸和组氨酸都是酵母氮代谢和发酵性能的重要氨基酸。
