产膜表皮葡萄球菌LuxS/AI-2型密度感应系统AI-2的活性及苦参碱对其的影响

Study on AI-2 signaling molecules activity and the effect of matrine on AI-2 in Staphylococcus epidermidis LuxS/AI-2 quorum sensing

【目的】研究产膜表皮葡萄球菌生物被膜菌和液相浮游菌LuxS/AI-2型密度感应系统中AI-2信号分子的活性及苦参碱对其的影响。【方法】绘制产膜表皮葡萄球菌ATCC35984液相浮游菌及生物被膜菌的生长曲线;利用哈维氏弧菌BB170(Vibrio harveyi BB170)作为报告菌株检测表皮葡萄球菌AI-2信号分子的活性;用荧光定量PCR法检测luxS基因的转录水平;用苦参碱对产膜表皮葡萄球菌ATCC35984进行处理,检测其AI-2信号分子活性的变化情况。【结果】在产膜表皮葡萄球菌液相浮游菌生长过程中,AI-2信号分子与luxS基因的相对表达量都是在对数生长期达到最大值,而后逐渐降低,与液相浮游菌生长曲线基本一致。在产膜表皮葡萄球菌生物被膜菌生长过程中,AI-2信号分子活性曲线与其生物被膜生长曲线变化趋势一致,但luxS基因的相对表达量曲线与生物被膜生长曲线变化趋势相反。中药苦参碱对产膜表皮葡萄球菌液相浮游菌和生物被膜菌AI-2信号分子活性有抑制作用,并且对液相浮游菌AI-2信号分子活性的抑制作用强于生物被膜菌。【结论】AI-2信号分子活性和luxS基因的相对表达量与产膜表皮葡萄球菌生物被膜菌及其液相浮游菌的生长相关;苦参碱能够显著下调产膜表皮葡萄球菌生物被膜菌和液相浮游菌的AI-2信号分子活性。

[Objective] This study investigated the activity of AI-2 signaling molecules in Staphylococ- cus epidermidis planktonic bacteria and biofilm bacteria and the effect of matrine. [Method] The growth curve of Staphylococcus epidermidis planktonic bacteria and biofilm bacteria was drawn and AI-2 concen- tration was measured using the V. harveyi bioluminescence assay. The transcription level of luxS gene was analyzed using real-time PCR. The AI-2 signaling molecules of Staphylococcus epidermidis ATCC35984 were treated with matrine and the changes of AI-2 signaling molecules activity were determined. [Result] In Staphylococcus epidermidis planktonic bacteria growth process,AI-2 signaling molecule activity and the relative expression quantity of luxS gene reached the maximum in the logarithmic phase before decreasing gradually. Their change curves were similar with planktonic growth curve. However, in the growth processof Staphylococcus epidermidis biofilm bacteria, the activity trend was similar with the biofilm growth. The relative expression quantity of luxS gene had an opposite trend to biofilm growth. Matrine had inhibitory effect on AI-2 signaling molecule activity in planktonic and biofilm bacteria, and the inhibitory effect was stronger to planktonic bacteria. [Conclusionl AI-2 signaling molecule activity and relative expression quan- tity of luxS gene highly correlated with the growth of Staphylococcus epidermidis and its biofilm forma- tion. Matrine significantly reduced the AI-2 signaling molecule activity of Staphylococcus epidermidis.