紫外消毒对污水中耐药细菌与基因的去除机制及耐药特征影响

Wastewater reclamation is the strategic solution to water scarcity in China. Disinfection is the necessary process to ensure the microbial safety of water reuse. However, antibiotic-resistant bacteria/genes, considered as "emerging contaminants", have been detected widely in wastewater, which turns to be a challenge to the existing wastewater disinfection technologies. The antibiotic resistance could be transmitted to pathogens during wastewater discharge or reuse. Thus, its health risk needs to be paid attention. In this study, the six kinds of most detected antibiotics (sulfadiazine、erythromycin、 cefazolin、vancomycin、gentamicin and tetracycline) were selected as the target antibiotics, relative antibiotic-resistant bacteria/genes were chosen as the tested antibiotic pollution. Based on the investigation of the prevalence and characteristics of selected antibiotic-resistant bacteria/genes in wastewater, the effects of UV disinfection technologies on antibiotic-resistant pollution will be studied. The project aims to investigate the inactivation and reactivation of antibiotic-resistant bacteria after UV irradiation. The elimination of antibiotic-resistant genes is to be studied by the means of Q-PCR. Furthermore, the effect of plasmid concentration and wastewater qualities such as UV-absorbed matters and particles on the removal of antibiotic pollution will be investigated. The selectivity and antibiotic resistance of bacteria and transformability of genes during the UV treatment process are to be explored. Base on this project, it is expected to provide a solution to antibiotic pollution control and microbial safety of disinfection.

近年来污水中"新型污染物"抗生素耐药细菌及耐药基因（抗性污染物）的不断检出，对现有污水消毒技术提出挑战。本课题拟以污水中检出较多的抗生素（磺胺嘧啶、红霉素、先锋霉素、万古霉素、庆大霉素及四环素）耐药病原指示菌（异养菌、粪大肠菌、肠球菌）及典型耐药基因（ereA、 tetA、sulI、AmpC、AacC1）为研究对象，在调研污水中耐药细菌/基因的污染特性基础上，研究紫外消毒技术对污水中抗性污染物的影响。考察紫外消毒对耐药细菌的灭活效能及其复活潜能，分析紫外对耐药细菌的选择性，研究耐药细菌抗生素抗性指数等特性变化；探索DNA损伤与耐药性的关系。通过Q-PCR定量检测技术，研究消毒对耐药基因的去除和破坏特征；考察质粒DNA浓度及种类和污水水质（吸光物质、颗粒物）对紫外辐照去除耐药基因的影响；探索消毒前后质粒介导的耐药基因的水平转移速率及其性能变化。该研究旨在为控制抗性污染物提供新思路和理论支撑。

耐药细菌及其基因作为新型污染物被提出，受到环境领域的关注。消毒作为控制水体微生物安全性的主要手段，对耐药细菌及其基因的研究尚在起步阶段。本项目选择广谱且环境友好的紫外线消毒技术，研究其对典型耐药细菌及其主要耐药基因的去除特性。分析了紫外线辐照对耐药细菌选择性的影响。在建立并优化接合转移模型基础上，探索了耐药基因在消毒过程中的接合转移和转化转移特征。研究发现，紫外线消毒可有效抑制耐药细菌的浓度水平，但会对耐药细菌具有一定的选择性。在研究的九种耐药细菌中，经紫外线照射后五种耐药细菌浓度水平上升，另外四种耐药细菌比例下降。选择性的机理可能与细菌种类有关。.紫外线消毒可以有效破坏耐药基因。尽管耐药细菌比例会在紫外线消毒后有所变化，提示选择性存在的可能性，但研究发现紫外线辐照对耐药基因显示明确的去除作用，这与紫外线直接破坏基因的机理有一定关系。.紫外线消毒对耐药基因转移的影响随着紫外剂量的变化而变化。低紫外线剂量下，由于耐药细菌浓度保持在转移阈值之上，故耐药基因接合转移水平保持不变；随着紫外剂量的增大，紫外线辐照明显抑制耐药基因接合转移。而对转化转移来说，紫外线辐照显示明显的抑制作用。以上研究表明，紫外线消毒技术可在一定程度上控制耐药性污染风险。