构建高产谷胱甘肽啤酒酵母基因工程菌提高啤酒抗老化能力的研究

根据同源重组的原理,将来源于啤酒酵母工业菌株G03的γ-谷氨酰半胱氨酸合成酶基因(GSH1)和筛选标记Kan取代质粒pRJ-5中18S rDNA内部约340bp的DNA片段,构建重组质粒pRKG。以pRKG为模版,PCR得到以18S rDNA为整合位点包含GSH1和Kan的基因片段18S rDNA::(Kan-GSH1)。用此片段转化啤酒酵母工业菌株G03,通过G418抗性筛选得到啤酒酵母工程菌。实验室小试表明,工程菌的谷胱甘肽含量比受体菌株提高16.6%,啤酒的抗老化能力得到了显著提高,而常规指标没有发生显著变化。连续传代5次后胞内GSH含量基本不变遗传稳定性良好。由于表达γ-谷氨酰半胱氨酸合成酶的基因来源于受体菌株自身,是通过自克隆技术改造工业啤酒酵母的一次有益的尝试。

Improvement of Beer Anti-staling Capability by Genetically Modifying Industrial Brewing Yeast with High Glutathione Content

Based on homologous recombination, recombinant plasmid pRKG was constructed by replacing the internal fragment of 18S rDNA of pRJ-5 with a copy of gamma-glutamylcysteine synthetase gene (GSH1) from the industrial brewing yeast strain G03 and a copy of G418 resistance gene (Kan) used as the dominant selection marker respectively. The fragment 18s rDNA::( Kan-GSH1) obtained through the PCR reaction was integrated to the chromosomal DNA of G03 strain, and recombinants were screened by G418 resistance. It was shown that the GSH content of beer fermented with the recombinant strain SG1 was 16.6% higher than that of G03, and no significant difference in routine fermentation parameters was found. To test the genetic stability, strains SG1 was inoculated into flasks and transfered continuously 5 times. The intracellular glutathione content of strain kept constant basically. It is an instructive attempt of genetically modifing industrial brewing yeast, as GSH1 was obtained from the host itself.