中文摘要：

目的：探讨伤寒沙门菌luxS基因在葡萄糖存在下对细菌对数生长中期基因表达调控的影响。方法：应用自杀质粒介导的同源重组方法制备伤寒沙门菌luxS基因缺陷变异株;比较野生株与缺陷株的生长情况及动力差异;用哈氏弧菌BB170作为报告菌株检测不同时期野生株与缺陷株的生物发光;利用伤寒沙门菌全基因组芯片技术,比较在葡萄糖存在下伤寒沙门菌野生株和luxS基因缺陷变异株的对数生长中期基因表达谱差异,并选择部分差异表达基因进行实时定量PCR验证。结果：经PCR及序列分析证实,伤寒沙门菌luxS基因缺陷变异株制备成功;在葡萄糖存在下野生株发光均比无葡萄糖时强,在对数生长中期时AI-2产生的荧光最强,而luxS缺陷株不发光;luxS不影响细菌生长但影响细菌的动力;基因表达谱比较分析结果表明,与野生株相比,luxS缺陷株有47个基因表达上调,27个基因表达下调;实时定量PCR结果与芯片分析一致。结论：伤寒沙门菌中luxS基因能参与信号分子AI-2的合成,且LuxS/AI-2在细菌对数生长中期的基因表达调控中发挥重要作用。

英文摘要：

Objective： To elucidate the influence of LuxS on gene expression regulation of Salmonella enterica serovar Typhi（S.Typhi） at mid-log phase in the presence of glucose.Methods： The luxS deleted mutant of S.Typhi was prepared by the homologous recombination mediated by suicide plasmid;the differences of growth and motility between wild-type（WT） and mutant were compared;luminescence assays were performed in WT and mutant at different growth phases in the presence and absence of glucose with reporter strain Vibrio harveyi BB170;the difference of gene expression profiles between the WT and the luxS mutant at mid-log phage in the presence of glucose was investigated by genomic microarray assay;qRT-PCR was performed to validate the results of microarray assay.Results： The luxS deleted mutant of S.Typhi was constructed successfully;luxS gene had effect on the bacterial motility but not on the bacterial growth;the luminescence of WT was higher at any growth phases in the presence of glucose than in its absence and reached the maximum at mid-log phase in the presence of glucose,while the mutant did not produce luminescence in both the presence and absence of glucose at any growth phases;gene expression profiles analysis revealed that expression of 47 and 27 genes were induced and decreased,respectively,in the luxS mutant at mid-log phases in the presence of glucose.The results of qRT-PCR are similar with that of genomic assay.Conclusion： The luxS gene of S.Typhi was involved in the synthesis of AI-2 and played a vital role in genes expression regulation at mid-log phase.