Wang Jin-jing, Xu Wei-na, Li Xin'er, Li Jia, Li Qi
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.
World J Microbiol Biotechnol. 2014 Jun;30(6):1901-8. doi: 10.1007/s11274-014-1617-0. Epub 2014 Feb 1.
The flavor stability during storage is very important to the freshness and shelf life of beer. However, beer fermented with a yeast strain which is prone to autolyze will significantly affect the flavor of product. In this study, the gene encoding β-1,3-glucan synthetase catalytic subunit (fks1) of the lager yeast was destroyed via self-clone strategy. β-1,3-glucan is the principle cell wall component, so fks1 disruption caused a decrease in β-1,3-glucan level and increase in chitin level in cell wall, resulting in the increased cell wall thickness. Comparing with wild-type strain, the mutant strain had 39.9 and 63.41 % less leakage of octanoic acid and decanoic acid which would significantly affect the flavor of beer during storage. Moreover, the results of European Brewery Convention tube fermentation test showed that the genetic manipulation to the industrial brewing yeast helped with the anti-staling ability, rather than affecting the fermentation ability. The thiobarbituric acid value reduced by 65.59 %, and the resistant staling value increased by 26.56 %. Moreover, the anti-staling index of the beer fermented with mutant strain increased by 2.64-fold than that from wild-type strain respectively. China has the most production and consumption of beer around the world, so the quality of beer has a significant impact on Chinese beer industry. The result of this study could help with the improvement of the quality of beer in China as well as around the world.
储存期间的风味稳定性对啤酒的新鲜度和保质期非常重要。然而，用易于自溶的酵母菌株发酵的啤酒会显著影响产品风味。在本研究中，通过自克隆策略破坏了贮藏酵母中编码β-1,3-葡聚糖合成酶催化亚基（fks1）的基因。β-1,3-葡聚糖是主要的细胞壁成分，因此fks1的破坏导致细胞壁中β-1,3-葡聚糖水平降低，几丁质水平升高，从而使细胞壁厚度增加。与野生型菌株相比，突变菌株中辛酸和癸酸的泄漏量分别减少了39.9%和63.41%，这两种酸在储存期间会显著影响啤酒的风味。此外，欧洲酿造协会试管发酵试验结果表明，对工业酿造酵母进行基因操作有助于提高抗老化能力，而不会影响发酵能力。硫代巴比妥酸值降低了65.59%，抗老化值提高了26.56%。此外，用突变菌株发酵的啤酒的抗老化指数分别比野生型菌株提高了2.64倍。中国是世界上啤酒产量和消费量最大的国家，因此啤酒质量对中国啤酒行业有着重大影响。本研究结果有助于提高中国乃至全球啤酒的质量。
