World Journal of Microbiology and Biotechnology ( IF 4.1 ) Pub Date : 2021-06-26 , DOI: 10.1007/s11274-021-03082-7 Xin Xu 1, 2 , Chengtuo Niu 1, 2 , Chunfeng Liu 1, 2 , Jinjing Wang 1, 2 , Feiyun Zheng 1, 2 , Qi Li 1, 2
Ethyl-acetate is important for the flavor and aroma of the alcoholic beverages, therefore, there have been extensive efforts toward increasing its production by engineering yeast strains. In this study, we reported a new approach to breed non-genetic modified producing yeast strain with higher ethyl-acetate production for beer brewing. First, we demonstrated the positive effect of higher acetic acid concentration on inducing the expression of acetyl-CoA synthetase (ACS). Then, we applied adaptive laboratory evolution method to evolve strain with higher expression level of ACS. As a result, we obtained several evolved strains with increased ACS expression level as well as ethyl-acetate production. In 3 L scale fermentation, the optimal strain EA60 synthesized more ethyl-acetate than M14 at the same time point. At the end of fermentation, the ethyl-acetate production in EA60 was 21.4% higher than M14, while the other flavor components except for acetic acid were changed in a moderate degree, indicating this strain had a bright prospect in industrial application. Moreover, this study also indicated that ACS1 played a more important role in increasing the acetic acid tolerance of yeast, while ACS2 contributed to the synthesis of cytosol acetyl-CoA, thereby facilitating the production of ethyl-acetate during fermentation.
中文翻译:
在高浓度醋酸条件下通过适应性实验室进化筛选具有较高乙酸乙酯产量的啤酒酵母
乙酸乙酯对酒精饮料的风味和香气很重要,因此,人们一直在努力通过工程酵母菌株来提高其产量。在这项研究中,我们报道了一种新的方法来培育用于啤酒酿造的具有更高乙酸乙酯产量的非转基因生产酵母菌株。首先,我们证明了较高浓度的乙酸对诱导乙酰辅酶 A 合成酶 ( ACS )表达的积极影响。然后,我们应用适应性实验室进化方法来进化具有更高ACS表达水平的菌株。结果,我们获得了几个ACS增加的进化菌株表达水平以及乙酸乙酯的产生。在3 L规模发酵中,最佳菌株EA60在同一时间点合成的乙酸乙酯比M14多。发酵结束时,EA60的乙酸乙酯产量比M14高21.4%,而除乙酸外的其他风味成分均发生适度变化,表明该菌株具有良好的工业应用前景。此外,本研究还表明,ACS1在提高酵母的乙酸耐受性方面发挥了更重要的作用,而ACS2有助于细胞质乙酰辅酶A的合成,从而促进发酵过程中乙酸乙酯的产生。