乳酸乳球菌镉抗性质粒的鉴定及镉抗性功能片段的获取

Identification of Lactococcus Lactis Cadmium Resistance Plasmid and Acquisition of the Cadmium Resistance Functional Fragment

为获得乳酸菌食品级筛选标记基因,通过质粒消除、PCR方法和电转化方法鉴定一个镉抗性质粒pCD077。酶切分析结果显示该质粒是一个50kb以上的大质粒。结合PCR及热不对称嵌套PCR的方法获得镉抗性功能片段,为以镉抗性为筛选标记构建乳酸菌食品级载体奠定了基础。

In order to obtain food-grade selection marker gene,the plasmid pCD077 which encodes resistance to cadmium was identified through plasmid curing,PCR and electrotransformation in this study.The size of pCD077 was estimated to be 50 kb by restriction analysis.It was difficult to analyze the sequence of the whole cadmium resistance plasmid for its large size.Therefore,the PCR and the thermal asymmetric interlaced PCR （TAIL-PCR） were adopted to acquire cadmium resistance functional fragment.The results were beneficial for constructing lactic acid bacteria food-grade vector based on cadmium resistance selectable marker.