用原生质体融合法优化啤酒酵母的凝絮性和发酵性能

Study on Optimization of Flocculence and Fermentation Characteristics of Brewer's Yeast by Protoplast Fusion

以发酵度较高、凝絮性较差的啤酒酵母菌株H38的原生质体为受体,以凝絮性较强、发酵度较低的啤酒酵母菌株N1热灭活的原生质体为供体进行融合.用正交试验法分别优化两亲株的原生质体制备和再生的条件以及原生质体融合的条件.用制霉菌素抗性为遗传标记选择融合子.融合子初筛时以凝絮性为指标,复筛时以发酵度和发酵液中的主要风味物质的含量为指标.对得到的融合子进行了异核体和遗传稳定性的检验,结果得到两株凝絮性以及发酵特性较好的菌株HN31和HN40.

The objective of this work was to optimize the flocculence and fermentation characters of brewer＇s yeast by protoplast fusion technology. Saccharomyces cerevisiae H38 and N1 were used as the parent strains for protoplast fusion. The strain H38 was a non-flocculence strain with a relatively high fermentation degree and the strain N1 was a strain with a relatively low fermentation degree and the relatively strong flocculence. The formational and regenerative conditions of strain H38 and N1 protoplast were optimized with the orthogonal test method. The protoplast fusants were constructed with H38 protoplasts as receptors and heat-inactivated strain N1 protoplasts as donors. The fusion conditions between strain H38 and N1 protoplast were optimized with the orthogonal test method. Anti-mycostatin character were used as genetic mark to select the fusion strains. Fusants were selected with flocculation ability, fermentation degree and content of diacetyl,acetaldehyde, total higher alcohols in the fermented liquid as screening criteria. As a result, two fine fusants with the relatively strong floccutence, high fermentation degree and low content of dicetyl, acetaldehyde and total alcohole in the fermented liquid were obtained.