前期,从新疆哈萨克族奶酪中分离到127株酵母菌,选取其中生长状况良好18株菌进行潜在益生酵母菌筛选试验。在不同胆盐质量浓度、不同pH值、模拟人体胃液及温度的条件下进行培养,并以大肠杆菌、金黄色葡萄球菌为指示菌,观察其抑制有害菌的能力,同时对菌株的表面疏水性及自动聚集能力也进行测定,系统的分析了菌株的益生特性。最终,在18株酵母菌中得到4株菌(Y1、H1、Y36-6、L4)在以上条件下有较好的存活率,为潜在益生酵母菌。并对这4株酵母菌进行生理生化试验及26S rDNA序列测定,将结果同NCBI数据库中提供的酵母菌序列进行比对,以DNA Star软件进行相似性分析,得到H1菌株属于马克斯克鲁维酵母菌属(Kluyveromyces)相似度为99%,Y1菌株属于酿酒酵母属(Saccharomycete)相似度为99%,Y36-6和L4属于毕赤酵母属(Pichia kudriavzevii)相似度99%。
18 strains of yeasts with good growth status were selected from 127 strains isolated from Xinjiang Kazakh cheese in the early stage for potential probiotic yeast screening. These strains were cultured in different bile salts concentration, pH value, simulated human gastric juice and temperature. Escherichia coli and Staphylococcus aureus were used as indicator bacteria to observe its ability to inhibit harmful bacteria. Meanwhile, the strain surface hydrophobicity and automatic aggregation ability were also measured, as well as the probiotic characteristics of the strains. Finally, 4 strains (Y1, H1, Y36-6 and L4) obtained from 18 yeasts with better survival rates under the above conditions were chosen as potential probiotic yeasts. The physiological and biochemical tests and 26S rDNA sequencing of these 4 yeasts were carried out. The results were compared with those provided by NCBI database, and similarity analysis was carried out by using DNA Star software. The results showed that H1 strain belonged to Kluyveromyces marxianus with similarity of 99%, the similarity of Y1 strain to Saccharomycete was 99%, and the similarity of Y36-6 and L4 to Pichia kudriavzevii was 99%.