糖化酵母在干啤酒生产中应用的研究（Ⅰ）──具有糖化酶活性和去除POF1基因的糖化酵母的选育

比较了多株单、双倍体糖化酵母，选出糖化酶活性及发酵度较高的糖化酵母单倍体──Ｓｏｃ．ｄｉａｓｔａｔｉｃｕｓ２６０６７－４４。同时发现糖化酵母单倍体菌株的酶活性高于二倍体菌株。含有ＰＯＦ１基因的糖化酵母（ｐｏｆ＋表型）可脱羧肉桂酸形成苯乙烯，ｐｏｆ－菌株无此能力。通过气相色谱检测肉桂酸－酒花麦汁发酵液中的苯乙烯含量，可以鉴别出去除ＰＯＦｌ基因的菌株。本文利用酵母菌的群体杂交法，通过Ｓ．ｄｉａｓｔａｔｉｃｕｓ２６０６７－４４与酿酒酵母单倍体杂交，获得１株糖化酶活性及发酵度较高，并且去除了ＰＯＦ１基因的单倍体菌株Ｈ－３（２）－２（ａ，ＳＴＡ，ｐｏｆ－）·

Study on the Application of S. Diastaticu s in Dry Beer( 1 )──Selection of Dextrin Fermentative Sac. Diastaticus Strainswith Eliminated POF1 Gene

he activity of extracellular glucoamylase excreted by Sac.diastaticus 26067-44 and its rate of fermentation is higher than those of other strains. We find that gulcoamylase secretion of S. diastaticus is 0controlled by the mating type locus MAT; haploid yeast cells secrete higher levels of the enzyme than dipolid cells.The yeast containing POF1 gene (pof penotype)can decarboxylate cinnamic acid to styrene.In contrast ,brewing yeast of pof- phenotype does not have the decarboxylase activity.Those strains whichwere eliminated POF1 gene can be identified by detected the content of styrene in their cinnamic acidhopped wort using gas chromotography.S.diastaticus 26067-44 (pof ) was mated with haploid brewing strain Y-4 (pof- ).The selectedhaploid segregant H-3 ( 2 )-2 (a,STA,pof- )can ferment the wort efficiently and is capable of degradingdextrin ,and unable to decarboxylate cinnamic acid.