市售酸乳中嗜热链球菌的分离及RAPD分析

Isolation and RAPD Analysis of Streptococcus thermophilus from Commercial Yoghurt

本研究采用选择性培养基,通过划线分离、显微观察及糖发酵实验,从市售酸乳中获得嗜热链球菌(Streptococcus thermophilus)8株。采用23个随机引物,分别对分离的8个嗜热链球菌菌株进行RAPD扩增,再运用NTSYSpc-2.10e软件,对所得扩增产物进行统计处理,得出8株嗜热链球菌之间的遗传相似系数矩阵和聚类分析图。结果表明,8个菌株相互间的遗传相似系数在0.4886～0.9313之间。当相似系数为0.6489时,S.t1、S.t3、S.t4、S.t5、S.t6、S.t7聚为一组,S.t2、S.t8聚为另一组;相似系数达到0.6947时,前者又聚为2个亚组,其中S.t1和S.t7为一亚组,而S.t3、S.t4、S.t5、S.t6为另一亚组。

Eight strains of Streptococcus thermophilus （St.） were obtained from eight brands of commercial yoghurt via streaking on the selective medium, microscopic observation and sugar fermentation assay, and then were subjected to RAPD amplification using 23 random primers, finally the genetic similarity coefficient matrix and clustering analysis plot among them were obtained according to the statistical analysis of RAPD fingerprint by using NTSYSpc-2.10e soft. The results revealed that the genetic similarity coefficients of the eight strains were between 0.4886 and 0.9313. When the similarity coefficient was 0.6489, S.t 1, S.t 3, S.t 4, S.t 5, S.t 6 and S.t 7 could be grouped in one group, S.t 2 and S.t 8 in another. When the similarity coefficient was 0.6947, the former group could be further grouped into two subgroups, S.t 1 and S.t 7 were in one subgroup and S.t 3, S.t 4, S.t 5 and S.t 6 were in another subgroup.