啤酒酵母FLO8基因敲除对酵母发酵性能的改良

Improvement of knockout flo8 gene in brewing yeast on yeast fermentation performance

利用PCR介导基因中断技术,以pUG6为模板,设计含有与flo8基因两侧序列同源的长引物,构建带有卡那抗性基因(KanMX)中断盒,转化啤酒酵母G-03,获得一株转化菌G-03/f8。对转化菌G-03/f8和原菌G-03进行生理生化性能和摇瓶发酵性能比较。该菌株在实验室常规发酵中,生理性能、发酵性能基本上与出发菌株保持一致。当用酵母提前絮凝(PYF,premature yeast flocculation)值高的麦芽糖化后的麦汁接种发酵时,G-03/f8的絮凝性能与常规发酵下的絮凝性能基本一致,此时明显优于出发菌株G-03。G-03/f8的酒精度、发酵度等低温发酵指标与常规发酵相比有小幅度的下降,但明显高于此时G-03的各项发酵指标。相对于出发菌而言,G-03/f8对高PYF值的麦汁不敏感,能够保持较好的发酵性能,因此在高PYF值麦芽的利用上有良好的应用前景。

To knockout of flo8 gene in industrial brewing yeast by PCR-mediated gene disruption.We obtained a deficient transformant G-03/f8 based on homologous recombination with KanMX gene,and the transformant was verified to be genetically stable.The PCR analysis showed that flo8 gene in the G-03/f8 was deleted.The properties of the transformant were investigated during flask fermentation on its fermentation routine parameters.Compared with the host strain G-03,G-03/f8 could reach the same level in growth and fermentation routine parameters.When using high PYF（premature yeast flocculation）value malt in brewing,the ethanol and fermentation degree of G-03/f8 decreased insignificantly,which was better than G-03 in the fermentation routine parameters.The G-03/f8 was insensitive to high PYF value wort,which insured the applying on it.