猪链球菌噬菌体SMP裂解酶在乳酸乳球菌中的表达及活性研究

Expression of the Phage Lysin LySMP in Lactococcus lactis and Studies on its Antibiotic Bioactivities

猪链球菌（Streptococcus suis,SS）烈性噬菌体SMP的宿主谱窄,制约了其临床应用潜力。研究发现,由噬菌体编码的裂解酶（LySMP）可有效拓宽其裂解谱。本研究以SMP基因组DNA为模板,扩增获得SMP裂解酶基因,将其克隆至质粒pNZ8148中,电转化乳酸乳球菌NZ9000,获得重组乳酸乳球菌NZ9000（pNZ8148-LySMP）,经Nisin诱导可表达LySMP。浊度递减实验结果显示,所表达的LySMP对7株猪链球菌2型菌株和猪链球菌9型菌株有较高的裂解活性,浊度下降可达30%~77%。表明利用NICE表达系统及pNZ8148表达载体在乳酸乳球菌中可实现猪链球菌噬菌体裂解酶的活性表达,为开展LySMP的应用研究提供了可能。

Streptococcus suis phage（SMP） shows narrow spectrum in its host range,which limited its potential application in clinic.Previous studies indicated that the bacteriophage lysine synthesized by LySMP could effectively broaden its lytic spectrum.In this study,the LySMP gene was obtained from the PCR amplification using SMP gene as the template and then was inserted into an expression plasmid of pNZ8148.The recombinant plasmid pNZ8148-LySMP was established by the electro-transformation of the pNZ8148 into Lactococcus lactis NZ9000 and the expression of LySMP was induced by Nisin.The degraded bacterial turbidity test showed that 7 strains of Streptococcus suis-2 and Streptococcus suis-9 possessed high sensitivity to SMP lysine and the turbidity could be decreased by 30%~77% in 30 min.It was concluded that SMP lysin has been successfully expressed in Lactococcus lactis using NICE expression system,providing the potential application of the LySMP in clinic.