GIS1基因对酿酒酵母耐受性的研究

该研究主要通过过表达GIS1基因来提高酿酒酵母的耐受性。在GIS1基因的N端加入强启动子PGK1p来实现GIS1基因的过表达，然后通过稀释点板实验来对比其对热激、乙醇、渗透压以及乙酸的耐受性，同时通过高温生长曲线和高温浓醪发酵测定其高温耐受性。结果表明，在相同的稀释倍数下，55 ℃热击4 min之后菌株AY12a-gis1的生长能力明显优于出发菌株，在含有5%（V/V）乙酸的平板上改造菌和出发菌耐受性相差不大，同时通过38 ℃浓醪发酵实验发现菌株AY12a-gis1的酒精度提高了3.79%，残糖略有下降，且发酵时间与亲本菌株相一致。因此通过过表达GIS1基因得到菌株AY12a-gis1，是对工业乙醇发酵有一定应用价值的优良耐逆性菌株。

Investigation on tolerance of gene GIS1 to Saccharomyces cerevisiae

Gene GIS1 was over-expressed to enhance the tolerance of Saccharomyces cerevisiae, by adding the strong promoter PGK1p to the N-terminus of GIS1, and then the tolerance to heat shock, ethanol, osmotic pressure, and acetic acid was compared through a dilution spot plate experiment. The high-temperature tolerance was determined by high-temperature growth curve and high temperature thick mash fermentation. Results showed that at the same dilution ratio, the growth ability of strain AY12a-gis1 after heat shock at 55 ℃ for 4 min was significantly higher than that of the original strain, and the tolerance of the transforming strain and original strain on the plate containing 5% acetic acid was similar. The results of high gravity fermentation at 38 ℃ showed that the ethanol content of strain AY12a-gis1 increased by 3.79%, and the residual sugar content decreased slightly. The fermentation time was consistent with that of the parent strain. Therefore, by overexpression of gene GIS1, a strain named AY12a-gis1 with excellent resistance to ethanol in industrial fermentation was obtained.