天然有机质介导的醌呼吸过程对纳米银环境行为的影响机制

Nanosilver is one of the most widely used nanomaterials due to its unique properties. The wide application of nanosilver-containing products has inevitably led to release vast quantities of nanosilver into the environment, which would posed threats to biosafety and ecological health. The ecological environmental risks of nanosilver have cause wide public concern. However, the recent researches about environmental risks of nanosilver mainly focus on the aerobic environments. The environmental risks under the anaerobic environment have not been systematically investigated. Therefore, the project would stress the environmental behaviors of nanosilver under the anaerobic environment. In the project, the anaerobic environmental behaviors of nanosilver would be investigated firstly and then the effects of natural organic matters would be taken into consideration. Then, the Shewanella sp. would be chosen as the research object to conduct the effects of anaerobic metabolism progresses on the environmental behaviors of nanosilver. Finally, on the basis of the above experiments the roles of quionoe respiration mediated by natural organic matters in the environmental behaviors of nanosilver would be explored and the relationships among nanosilver, microbe and humic substances would be illustrated. Furthermore, by combination with the test results of the microbial growth metabolism the effect mechanisms of quinone respiration mediated by natural organic matters on the environmental behaviors of nanosilver would be revealed. This project would be helpful to deepen the cognition about the problems of environmental behaviors of nanosilver.

纳米银因其独特的性质成为应用得最为广泛的一类纳米材料。纳米银的普遍应用必然导致大量未经处理的纳米银排到环境中，将对生物安全和生态健康构成威胁。纳米银的生态风险已引起人们关注。目前关于纳米银生态风险的研究主要集中在有氧环境，对厌氧环境下纳米银的生态风险尚缺乏系统的研究。因此，本项目将重点研究纳米银在厌氧条件下的环境行为。项目拟从纳米银在厌氧条件下的环境行为入手，在此基础上考虑天然有机质对纳米银环境行为的影响，进而以希瓦氏菌为研究对象，研究微生物厌氧代谢过程对纳米银环境行为的影响，最后在上述研究的基础上研究天然有机质参与下的醌呼吸过程对纳米银环境行为的影响，揭示纳米银-微生物-腐殖质三者之间的相互联系，同时结合微生物生长代谢的检测数据，阐明天然有机质参与下的醌呼吸过程对纳米银环境行为的影响机制。通过本项目的研究可以加深对纳米银环境行为的认知。

纳米银因其独特的性质成为应用得最为广泛的一类纳米材料，纳米银的普遍应用必然导致大量未经处理的纳米材料排入环境，将对生物安全和生态健康构成危胁。目前关于纳米银生态风险的研究主要集中在有氧环境，对缺氧环境下纳米银生态风险的研究相对较少。项目从纳米银在缺氧条件下环境行为入手，以希瓦氏菌为研究对象，探讨了天然有机质对纳米银稳定性、毒性效应和生物代谢过程的影响，在此基础上引入电子供体，研究缺氧条件下纳米银-天然有机质-电子供体三者之间的相互作用对希瓦氏菌醌呼吸过程的影响，最后结合纳米银环境行为检测结果，阐明天然有机质参与下的醌呼吸过程对纳米银毒性效应的影响机制。研究结果表明，缺氧条件下天然有机质增加纳米银的稳定性，暂时缓解了纳米银对希瓦氏菌的毒性效应，可能是因为天然有机质或其模式物（蒽醌-2,6-双磺酸钠，AQDS）分别作为电子供体和电子受体调节着希瓦氏菌呼吸链的电子传递过程。在琥珀酸-纳米银-AQDS体系中，低浓度AQDS与琥珀酸协同作用缓解纳米银短期毒性，却导致胞内抗氧化酶活性增加，而高浓度AQDS与琥珀酸协同作用增加了纳米银的毒性和胞内抗氧化酶活性，这是可能因为低浓度AQDS作为电子穿梭体，接受来自琥珀酸的电子，促进Ag+还原生成Ag0，从而缓解了纳米银短期毒性效应，然而细胞呼吸链的电子载体对AQDS和Ag+亲和力不同，高浓度AQDS与Ag+竞争电子，降低了Ag+还原效率，导致纳米银的毒性效应增加。该项研究结果加深了对纳米银环境行为的理解，对进一步准确评价纳米银的生态环境风险和环境归宿也具有一定的指导意义。