中文摘要：

目的：通过构建pCAT3启动子陷阱载体筛选甲型副伤寒沙门菌噬菌体LSPA1启动子。方法：PCR无义突变去除pCAT2载体骨架上CalⅠ酶切位点，并在CAT片段的5’端引入CalⅠ的酶切位点，构建启动子陷阱载体pCAT3。 TaqⅠ酶切噬菌体LSPA1基因组，插入pCAT3载体中，转化至大肠杆菌DH5α，通过氯霉素抗性平板筛选获得噬菌体LSPA1基因文库菌；随机挑取1株提取质粒，测序及比对分析插入序列；根据分析结果设计引物，扩增可能的启动子序列，并插入验证载体p-3lysm-egfp，转化DH5α，荧光显微镜观察。结果：成功构建pCAT3启动子陷阱载体，获得约100启动子文库菌，其中1株文库菌质粒中随机插入片段可能对应噬菌体LSPA1的 ORF4启动子；插入待验证DNA片段的p-3lysm-egfp载体重组菌在荧光显微镜下能见到明显绿色荧光。结论：该启动子文库可有效筛选噬菌体LSPA1启动子，为进一步深入研究噬菌体LSPA1提供帮助。

英文摘要：

Aim：To screen promoter of Salmonella paratyphi A phage LSPA1 through promoter trap vector pCAT 3. Methods：CalⅠrestriction site on plasmid pCAT 2 backbone was deleted by PCR nonsense mutation , and then the CAT gene with new CalⅠon the 5′end was inserted into pCAT2 to get promoter trap vector pCAT3.The digested fragment of LSPA1 phage genome was inserted to pCAT 3 and then transformed into E.coli DH5α.The bacteria phage LSPA1 promotor library was screened using plates containing chloramphenicol .After plasmid was extracted from a randomly picked bacteri-al, the information of inserted sequences was gained by sequencing .According to the results , primers were designed to am-plify the possible promoter sequence and inserted to plasmid p-3lysm-egfp.After this plasmid was transformed into DH 5α, the recombinant bacteria were observed under fluorescence microscopy .Results：Promoter trap vector pCAT3 was success-fully constructed .About 100 bacteria containing promoter were gained , one of which was presumed to be ORF 4 promoter of phage LSPA1.Recombinant bacteria DH5α/p-3lysm-egfp carried the insert DNA fragments was obviously observed green fluorescence under fluorescence microscope .Conclusion： This library can effectively screen phage LSPA 1 promoter, which would be helpful for further research of phage LSPA 1.