18S rDNA介导的FKS1基因过表达对酵母自溶性能的影响

Overexpression of FKS1 to improve yeast autolysis-stress

酵母被誉为啤酒酿造的灵魂,然而随着啤酒高浓酿造技术的发展,酿造过程中渗透压增加、乙醇含量升高及营养平衡改变等会加快酵母的自溶,对啤酒的风味品质产生不利的影响。为提高酵母的抗自溶能力,本研究构建了以酿酒酵母18S r DNA序列为同源位点的FKS1过表达菌株。结果表明,过表达菌株细胞壁葡聚糖含量较原菌高62%;通过平板耐受性分析可知,FKS1过表达菌株在8%的乙醇浓度、0.4 mol/L Na Cl的渗透压冲击以及24 h饥饿培养的条件下,其胁迫耐受性均高于原始菌株;模拟自溶实验结果显示FKS1过表达菌株自溶速度缓慢,抗自溶能力明显优于原始菌株。该结果有助于探究酵母自溶的机理,同时也对提高啤酒风味品质和稳定性有着重要的意义。

With the development of high gravity brewing, yeast cells are exposed to multiple brewing-associated stresses, such as increased osmotic pressure, enhanced alcohol concentration and nutritional imbalance. These will speed up yeast autolysis, which seriously influence beer flavor and quality. To increase yeast anti-autolytic ability, FKS1 overexpression strain was constructed by 18S rDNA. The concentration of β-l,3-glucan of overexpression strain was 62% higher than that of wild type strain. Meantime, FKS1 overexpression strain increased anti-stress ability at 8% ethanol, 0.4 mol/L NaC1 and starvation stress. Under simulated autolysis, FKS1 showed good anti-autolytic ability by slower autolysis. These results confirms the potential of FKS1 overexpression to tackle yeast autolysis in high-gravity brewing.