肉鸭消化道酵母益生菌热胁迫耐受性及其机理研究

Study on tolerance and mechanism of probiotics yeast under heat stress in ducks digestive tract

从肉鸭消化道内分离筛选出的5株酿酒酵母益生菌中,筛选高耐热性的菌株,并探究酵母菌胞内热休克蛋白表达与环境温度的相关性。通过热应激处理比较不同菌株的耐热性,然后对酵母细胞破壁,释放胞内蛋白,再利用SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE电泳)技术,分析不同菌株的热应激蛋白表达特性。结果显示,5个酿酒酵母菌株中有4株在常态时即存在热休克蛋白70家族和90家族热激蛋白的少量表达。3号酵母菌株在45℃和48℃相对于其他菌株而言耐受性更佳,其热休克蛋白70家族和90家族表达水平也更高。本试验还显示,冻融、超声波、高压均质三种不同破壁方法相比较,高压均质法效果最好。最佳工艺条件为:均质压力140 MPa,循环3次,原菌液稀释102倍,此时胞壁破壁率可达94.54%。可见,肉鸭消化道酵母菌株的耐热性存在差异,不同菌株的耐热性与热休克蛋白70家族和90家族的表达密切相关。试验菌株中3号菌株的热应激耐受性最佳,可以作为后续肉鸭专用饲用酵母益生菌的备选菌株。

We screened high heat resistant strains from 5 Saccharomyces cerevisiaes which we separated from the digestive tract of the meat duck. And we explored the correlation between heat shock protein expression in yeast cell and the environment temperature. Compare the heat resistance of differentstrains through the heat stress treatment and analyse the expression features of heat stress protein indifferent strains by using SDSpolyacrylamide gel electrophoresis(SDSpage electrophoresis). The results showed that 4 Saccharomyces cerevisiaes expressed a little heat shock protein of 70 family and90 family. At 45 ℃ and 48 ℃ the heat resistance of No.3 strain is better than the other strains and it'sexpression level of heat shock protein 70 family and 90 family is higher. At the same time, the experiment also showed that the best method to break the cell wall has a high pressure homogeneous otherthan the freezing and thawing methods 140 MPa homogeneous pressure, cycling three times and theoriginal bacterium liquid dilution 102 times isoriginal bacterium liquid dilution 102 times isthe optimum technological condition. The brokenrate of cell wall reached 94.54%. In conclusionthere are different heat resistant for the digestivetract of probiotics. Different strains of heat resistance play an important role in expression ofheat shock protein 70 family and 90 family, theheat stress tolerance of test strains 3 is best, which could be used as a followup for every special probiotic candidate forage yeast for duck.