1. 毕业设计（论文）的内容和要求

抗生素的滥用极大加剧了细菌耐药性的产生和发展，严重威胁公共安全[1-2]. 抗性基因作为一种新型环境污染物被提出，受到国际社会的高度关注[3]. 地表水是城市径流和污水的受纳水体，为抗性基因的存活及传播提供了良好的环境，成为环境中抗性基因的重要污染源. 已在不同国家的河流、湖泊中检出多种抗生素和抗性基因[4-5]，主要来源于城市污水、养殖废水等的排放[1-2]. 近年来，我国学者也高度关注环境中抗性基因的污染. 以长江为例，已报道检出超过100种抗性基因[6]，相对丰度可达20%以上[7]；以长江为水源的南京某自来水厂出水中也检出包括抗四环素、红霉素和磺胺等在内的多种抗性基因[6]，表明长江特别是下游区域耐药性污染情况十分严峻. mcr-1和ndm-1是近年来发现的两种新型抗性基因. mcr-1于2015年首先在我国人和畜禽体内被检出[8]，随后陆续在亚洲[9-13]、欧洲[14-15]和北美很多国家[16-18]发现，其编码多粘菌素类抗生素耐药性，而后者被认为是抵御细菌耐药性的”最后一道防线”. ndm-1编码β-内酰胺类抗生素水解酶，但后来发现其具有多重耐药能力，对除多黏菌素外的所有抗生素具有耐药性[19]，ndm-1携带菌也已在很多国家患者或动物体内检出[20-24]，被称为”超级细菌”. 上述抗性基因均通过质粒介导，水平转移能力很强，健康风险远大于传统抗性基因. 但相比于临床卫生领域，对其在环境中的研究较为稀少. 部分研究者已在养殖场、污水、河流和海洋等各种环境中分离出携带上述抗性基因的细菌[25-33]，表明mcr-1和ndm-1在环境中也普遍存在. 然而考虑到环境中大部分细菌为不可培养[34]，如果仅通过分离宿主菌进行研究难以全面地反映基因的环境风险. yang等[35-36]通过定量pcr针对ndm-1在河流和污水厂中的分布特征进行考察，为该类基因环境行为的研究提供了很好的范例. 该研究拟针对mcr-1和ndm-1在南京地区典型自来水厂中的分布特征和耐药特征展开研究. 首先考察mcr-1和ndm-1的检出、丰度及其空间分布特征，进而考察携带菌耐受抗生素能力的变化。

论文的数据必须实事求是。

通过论文将自己的实验结果通过图表、文字分析等步骤，按照逻辑方式得出结论。

2. 参考文献

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3. 毕业设计（论文）进程安排

起讫日期 设计（论文）各阶段工作内容 备 注 查找收集文献资料、撰写开题报告 2周 准备实验器材和实验药品 2周 实验阶段 8周 处理数据、撰写论文 5周 答辩 1周