纳米零价铁胁迫下功能型生物膜形成的群体感应机制研究

A great many nanoscale zero valent iron (nZVI) could easily get into wastewater treatment system owing to its widespread application in the field of contaminated environment remediation. The biofilm formation and maintenance of pollutant-degrading bacterium was crucial for pollutant removal and stability in wastewater treatment system. Recent researches have showed that ENPs had remarkable effect on biofilm formation. However, comparatively little is known about the influence mechanism about biofilm formation for pollutant-degrading bacterium under NP exposure. Therefore, based on the quorum sensing theory, we focused on the impact of nZVI on degrading bacterium which has been widely studied before. Firstly, the biofilm formation rate, physicochemical properties and pollutant-degrading ability were conducted to investigate the influence of exposed nZVI on biofilm formation and performance of the degrading bacterium. Furthermore, amount of extracellular signaling molecules (auto-inducers), public good, toxin, ROS and c-di-GMP generated from the degrading bacterium were determined in order.to dissect the physiological and ecological mechanism towards the impact of biofilm formation exerted by nZVI. Finally, the molecular mechanism about the effect of nZVI on biofilm formation was revealed via comparing the difference of transcriptional regulatory factor and regulatory networks controlled by quorum-sensing. The achievement of this study is not only helpful to enrich correlation theories regarding to the impact of ENPs on microorganism in wastewater treatment system at the microbial community level, but also lay a foundation to understand the effect of quorum-sensing by exogenous substances in nanoscale.

随着纳米零价铁(nZVI)在环境修复领域的广泛应用大量进入废水处理系统。降解菌生物膜的形成对污染物去除及系统稳定性至关重要。已有研究显示nZVI对微生物个体及群体活性不尽相同，nZVI对微生物个体影响并不能作为对生物膜影响的判断依据。nZVI对污染物降解菌生物膜形成及影响机制仍存在较多理论空白。本项目拟以群体感应为切入点，选择nZVI为研究材料，以研究较透彻的高效降解菌为研究对象，通过生物膜理化结构及对污染物降解的分析，明确 nZVI对生物膜形成及功能的影响;通过信号分子、公共物质及毒素释放，氧自由基及c-di-GMP产生的分析，剖析nZVI对生物膜形成影响的生理生态机理;通过群体感应转录因子及其调控多级基因差异的对比，解析nZVI对生物膜形成影响的分子机制。预期成果不仅从微生物群体层面丰富nZVI对废水处理系统中微生物影响的相关理论，也可从纳米尺度理解外源物质对群体感应的影响奠定基础。

随着纳米零价铁(nZVI)在环境修复领域的广泛应用大量进入废水处理系统。降解菌生物膜的形成对污染物去除及系统稳定性至关重要。nZVI对污染物降解菌生物膜形成及影响机制仍存在较多理论空白。本项目拟以群体感应为切入点，选取四种不同的零价铁颗粒（ZVI）：未修饰纳米零价铁，磷酸修饰纳米零价铁，草酸修饰纳米零价铁，微米级零价铁为研究材料，以前期项目组研究较透彻的铜绿假单胞菌为研究对象，系统研究ZVI对细菌的生理生态，生物膜形成及对污染物降解的影响；从ZVI对菌株群体感应信号分子、公共物质、调控基因的变化规律等方面揭示ZVI介导下微生物的生物膜形成的群体感应调控机制；在ZVI长期暴露下，从细胞膜通透性、基因靶位点确定、蛋白模型拟合等不同层面深入揭示了进化菌株的抗生素敏感性增加的分子机制。预期成果不仅从微生物群体层面丰富nZVI对微生物生态安全影响的相关理论，也可从全新的角度提出消减微生物抗生素抗性基因传播的绿色方法，为纳米颗粒等新兴材料的健康发展提供技术支持。