中文摘要：

以一株分离自牛乳中乳酸乳球菌染色体DNA为模板，采用PCR技术扩增出乳链菌肽生物合成的双组分调控元件（nisRK基因）。试剂盒回收纯化nisRK基因后将其克隆入以氨苄青霉素为选择压力的pGEM—T克隆载体中，再转化E．coliDH5a感受态细胞，筛选阳性克隆，提取重组体，进行酶切鉴定和PCR鉴定，并对nisRK基因进行序列测定，与已知序列进行同源性比较。结果表明成功地克隆出nisRK基因，全长为2035bp，与国外报道的nisRK基因同源性高达99．9％。

英文摘要：

Using chromosome DNA of Lactococcus lactis isolated from milk as template, nisRK gene was amplified by PCR with Pfu DNA polymerase. After purification, the PCR product was cloned into pGEM- T vector containing ampicillin resistance gene to generate recombinant plasmid pGEM-T： ： nisRK. Then pGEM-T： ： nisRK was transformed into E. coli DH5α competent cells. Identification by restriction en- donuclease digestion and PCR technique showed that the whole nisRK gene was cloned successfully. Sequence analysis indicated that nisRK gene, 2 035 bp, displayed 99.9 % nucleotide homology with the published abroad.