摘要
为了获得低产双乙酰的菌株,从保藏的啤酒工业酵母菌种中分离甲磺隆(SM)抗性自发突变株,经低温发酵测定发酵液的发酵度和双乙酰等啤酒风味物质的含量,结果得到ZT21-9-2等5株优良的SM抗性株.其中SM抗性株ZT21-9-2用500 L发酵罐发酵8 d,发酵液的发酵度为68.4%,发酵液的双乙酰、总高级醇和乙酸的含量分别为0.036 3、79.53和74.90 mg/L,该菌株具有很好的应用前景.为了探讨致使乙酰乳酸合成酶(ALS)编码基因ILV2突变而使ALS结构改变的关键碱基,为构建低产双乙酰的啤酒酵母工程菌提供依据,作者比较了SM抗性株ZT21-9-2及其亲株EY2-1的ILV2基因的DNA序列,结果发现SM抗性株ZT21-9-2共有6个碱基发生了转换,1个碱基发生了颠换.
In order to gain brewer＇s yeast strains of low diacetyl yield,sulfometuron methyl （SM）-resistant spontaneous mutants were isolated from brewer＇s yeast strains kept in our laboratory. After low temperature fermentation,five SM-resistant strains with good fermentation characteristics were screened out by the determination of fermentation degree and the flavor elements contents such as diacetyl,total high alcohols and acetate in the fermented liquid. ZT21-9-2 is one of the strains with good application prospects. Following 8 days＇ fermentation in the 500 L fermentor at 12℃ ,the fermentation degree of mutant ZT21-9-2 was 68.4 %,the contents of diacetyl,total high alcohols and acetate in the fermented liquid were respectively 0. 036 3,79.53 and 74.90 mg/L. To find out the key mutation zone of the ILV2 gene which could lead to the disfunction of acetolactate synthase （ALS）, and to provide the mechanism for the construction of low diacetyl brewer＇s yeast,the DNA sequences of the ILV2 gene encoding ALS of SM-resistant mutant ZT21-9-2 and its parent strain EY2-1 were compared,and six bases transition and one base transversion in the ILV2 gene of strain ZT21-9-2 were found.
出处
《厦门大学学报（自然科学版）》
CAS
CSCD
北大核心
2008年第5期718-722,共5页
Journal of Xiamen University：Natural Science
基金
英博雪津啤酒有限公司资助
