B型链球菌数量感应通路测定及LuxS缺失突变株的构建

目的 对GBS中可能存在的AI-2数量感应通路进行测定,构建数量感应相关分子LuxS缺失突变株并对其基因型进行确认。方法 培养GBS至不同D(λ)值,利用V.harveyi BB170作为报告菌株,对GBS诱导生物发光的能力进行测定,然后寻找GBS中LuxS同源基因,通过同源重组法在GBS中构建LuxS缺失突变株,Southern杂交分析确证。结果 GBS中的某种分泌成份可在报告菌株中诱导生物发光活性,提示GBS中存在AI-2数量感应通路,在GBS中发现了LuxS同源基因并成功地构建了LuxS缺失突变株。结论 本研究为探索LuxS在GBS中AI-2数量感应通路中的重要性及GBS毒力研究建立了细菌模型。

Detection of quorum-sensing pathway and construction of LuxS gene deletion mutants of group B Streptococcus

Objective To detect the possible presence of AI-2 quorum-sensing pathway and construct group B Streptococcus (GBS) mutants with deletion of LuxS gene related to quorum-sensing pathway. Method V. harveyi BB170 was employed as the reporter strain to detect AI-2 pathway in GBS, and identification of LuxS homologous gene in GBS type V strain 2603 was performed by software-based analysis. LuxS gene deletion mutant ΔLusX was then constructed in GBS by means of allelic exchange and verified by Southern hybridization analysis. Results A component in the secretions of GBS could induce bioluminescence activity in the reporter strain, suggesting the presence of AI-2 quorum-sensing pathway in GBS. luxS homologous gene was detected in GBS and LuxS gene deletion mutants was successfully constructed in GBS Ia 515 and V 2603 strains. Conclusion This study establishes a bacterial model for studying the role of LuxS molecule in AI-2 quorum-sensing pathway in GBS and provides new insights into virulence regulation mechanism of GBS.