嗜热链球菌CRISPR-Cas系统的检测

Detection of CRSPR-Cas system in Streptococcus thermophilus

摘要:

[目的] CRISPR-Cas系统为嗜热链球菌抵抗噬菌体等外源基因元件提供获得性免疫,分析NCBI中已公开发表全基因组序列的9株嗜热链球菌所含CRISPR-Cas系统的数目和类型,对实验室相应菌株的CRISPR-Cas系统进行检测。[方法] 利用生物信息学方法对NCBI中9株已测序嗜热链球菌所含CRISPR-Cas系统进行分析,根据其Cas基因序列设计引物,对实验室嗜热链球菌菌株的Cas基因进行扩增、测序,分析实验室6株嗜热链球菌的CRISPR-Cas系统情况。[结果] 9株标准菌株均含不同数目的CRISPR-Cas系统,其类型主要为Ⅱ-A型、Ⅲ-A型和Ⅰ-E型,各类型的标志Cas基因高度保守。6株供试菌中,S4仅含Cas9基因,其它5株均含有Cas9基因、Cas10基因和Cas9^*基因,79和KLDS3.0207还含有Cas3基因。[结论] 可根据标准菌株高度保守的Cas基因设计引物,预测未知嗜热链球菌所含CRISPR-Cas系统的数目和类型。S4仅含1个Ⅱ-A型CRISPR-Cas系统,其它5株均含有2个Ⅱ-A型CRISPR-Cas系统和1个Ⅲ-A型CRISPR-Cas系统,此外,79和KLDS3.0207均含有1个Ⅰ-E型CRISPR-Cas系统。

Abstract:

[Objective] We aimed to detect the CRSPR-Cas system of six Streptococcus thermophilus. [Methods] Bioinformatics method was used to predict CRSPR-Cas system of nine S. thermophilus that published in National Center for Biotechnology Information. Four primers were designed according to the flanking sequences of standard strains and the CRISPR-Cas system of six S. thermophilus have been detected by PCR method. [Results] S. thermophilus S4 had a Cas9 gene, others all had Cas9 gene, Cas10 gene and Cas9^* gene. In addition, 79 and KLDS3.0207 still had Cas3 gene. [Conclusion] Signature genes amplification of CRSPR-Cas system could predict the type of CRSPR-Cas system in unsequenced strains, these findings will help establish the foundation for the study of CRSPR-Cas system in lactic acid bacteria.