潮汐-复合流人工湿地系统优化及对抗生素抗性基因的去除效果

抗生素抗性基因随废水排放传播扩散,对环境生物和民众健康构成严重威胁.针对废水中抗性基因的深度去除值得重点关注.在前期研究中发现潮汐流人工湿地能有效去除废水中多种氮素.本研究通过增加隔板和种植植物等方式进一步优化潮汐流人工湿地系统,并考察了工艺优化对抗性基因去除和脱氮功能微生物的影响机制.结果表明,同时增加隔板和种植植物后的潮汐-复合流人工湿地系统能有效提高抗性基因的去除效率,在增加隔板和种植植物组对7类21种抗性基因去除率最高达到83.82%~100.0%,显著高于单一增加隔板或种植植物组.从湿地基质和植物中的抗性基因绝对丰度对比可以看出,增加隔板能促进湿地基质中抗性基因量积累,而植物对抗性基因吸附也是其去除途径之一.同时,结合氮循环功能基因测序结果显示,湿地系统优化能提高基质中硝化和反硝化功能微生物物种多样性和丰富度,这与优化系统对废水中硝化量、反硝化量和总氮的去除率相对更高结果一致.     

斑鳢等鱼贝类去毒相关基因的克隆

采用RT-PCR和RACE法,克隆得到斑鳢、鲢鱼CYPlA与斑鳢HSP70基因cDNA的核心序列,序列长度分别为908 bp、902 bp、684 bp,分别编码302、300、228个氨基酸;还克隆得到斑鳢、近江牡蛎GPX基因cDNA的部分序列,长度分别为720 bp、727 bp,分别编码119、232个氨基酸.多个重要养殖水生动物的去毒相关基因的成功克隆,为水产养殖动物去毒相关基因结构、功能、表达调控研究以及今后定向筛选高食用安全保障的水产品奠定基础.     

牛粪堆肥系统环境因子对抗性基因的影响

本研究利用实时定量PCR技术检测牛粪60 d好氧堆肥过程中典型四环素类抗性基因(tet Q、tet W、tet M、tet G、tet A和tet X)和大环内酯类抗性基因(erm35、erm36、erm B、erm F、erm T和erm X)的数量变化规律,系统研究了温度、含水率、挥发性有机质(VS)含量、碳氮比(C/N)、pH值、氧化还原电位(ORP)等堆肥系统环境因子和细菌数量(TCB)对这两类典型抗生素抗性基因的影响.结果表明,堆肥升温阶段牛粪中tet Q、tet W、tet G和tet X数量分别增加1. 7、0. 3、84. 8和4. 5倍,而tet M丰度降低了83. 1%;堆肥腐熟阶段牛粪中tet G和tet X数量分别增加23. 8和11. 5倍,而tet W、tet Q和tet M数量均降低90%.整个牛粪堆肥过程中erm35、erm36、erm B、erm F、erm T和erm X丰度分别增加2. 1、430. 4、0. 6、11. 5、2. 1和49. 1倍. RDA分析表明,牛粪堆肥过程中对四环素与大环内酯类抗性基因数量影响较大的3个环境因子分别为:ORP(54. 8%)、温度(34%)和VS(11. 3%),其中ORP与erm X和erm B、温度与tet Q和erm F以及VS与tet W数量均呈明显地正相关.     

磺胺嘧啶对鱼菜共生系统氮元素转化的影响

本文研究了典型抗生素磺胺嘧啶对实验室规模鲤鱼-小白菜共生系统生产性能和氮元素转化的影响.结果表明,磺胺嘧啶使系统鲤鱼体重增量提高17%,但小白菜生产性能大幅下降,使得系统氮素利用率由43.66%降至21.20%,N₂O转化率由1.02%上升至1.98%.磺胺嘧啶在投加初期对系统的硝化过程表现出短期抑制效应,经过32d的适应期后,实验组氨氮浓度下降至和对照组相近水平,系统运行后期实验组氨氧化细菌丰度相较对照组提高51.43%.鱼体内残余的磺胺嘧啶为35.23μg/kg,符合国家标准,但水体中磺胺类药物抗性基因sul1、sul2及intI1的拷贝数分别提升至7.23倍、2.74倍和4.12倍.从生产性能及环境友好性考虑,鱼菜共生系统在设计及运行中应减少或避免抗生素的使用,并采取合理的替代措施规避其风险.     

氯和紫外消毒过程中胞外抗性基因的产生特征

考察了城市污水氯和紫外消毒过程中不同物理形态的胞外抗性基因的产生行为与及微生物群落的关联特征.结果表明,氯消毒尽管使胞内抗性基因丰度下降,但使结合型胞外抗性基因丰度明显上升（0.7±0.1）log,而游离型胞外抗性基因丰度下降（0.2±0.1）log.紫外消毒也使胞内抗性基因下降,但使游离型胞外抗性基因显著上升（0.4±0.2）log,而结合型胞外抗性基因丰度下降（0.3±0.1）log.氯消毒后,结合型胞外DNA（a-eDNA）中变形菌门丰度下降而其他菌门的丰度上升,细菌多样性指数由4.2上升到4.7;而游离型胞外DNA（f-eDNA）中变形菌门上升了6.6%,多样性指数则从3.5降低到2.8.紫外消毒后,a-eDNA中变形菌门丰度下降了36.6%,多样性则上升到4.8,而f-eDNA中细菌丰度变化较小.分子生态网络分析揭示了抗性基因与细菌间广泛的寄存关系,tetA、tetX、sulI和sulII分别与17、15、15和5种菌属间存在共现性,表明抗性基因潜在宿主的变化是导致消毒后胞外抗性基因产生的关键原因.本研究表明氯和紫外消毒不能消除抗性基因风险,反而通过导致不同胞外抗性基因的大量产生,使风险的形式发生变化.     

水产养殖环境中抗生素抗性基因的研究进展

为摸清我国水产养殖环境抗生素抗性基因（Antibiotic resistance genes,ARGs）污染状况,统计了当前水产养殖环境水、沉积物和养殖对象中七大类抗性基因的赋存状况,进一步分析了影响其赋存的因素,对未来我国水产养殖ARGs污染研究进行了展望.水产养殖环境中ARGs主要以iDNA形式存在;磺胺类和四环素类抗性基因的丰度和检出率较高,被认为是水产养殖环境主要的ARGs,已受到当前研究的广泛关注;而喹诺酮类、氯霉素类、β-内酰胺类、大环内酯类和氨基糖苷类抗性基因报道的丰度和检出率相对较低.养殖过程中,养殖用药、饲料及养殖模式是影响水产养殖环境ARGs赋存的主要因素,但环境理化因子调节养殖环境ARGs的作用也不容忽视.     

Removal of antibiotic-resistant genes during drinking water treatment: A review

Once contaminate the drinking water source, antibiotic resistance genes (ARGs) will propagate in drinking water systems and pose a serious risk to human health. Therefore, the drinking water treatment processes (DWTPs) are critical to manage the risks posed by ARGs. This study summarizes the prevalence of ARGs in raw water sources and treated drinking water worldwide. In addition, the removal efficiency of ARGs and related mechanisms by different DWTPs are reviewed. Abiotic and biotic factors that affect ARGs elimination are also discussed. The data on presence of ARGs in drinking water help come to the conclusion that ARGs pollution is prevalent and deserves a high priority. Generally, DWTPs indeed achieve ARGs removal, but some biological treatment processes such as biological activated carbon filtration may promote antibiotic resistance due to the enrichment of ARGs in the biofilm. The finding that disinfection and membrane filtration are superior to other DWTPs adds weight to the advice that DWTPs should adopt multiple disinfection barriers, as well as keep sufficient chlorine residuals to inhibit re-growth of ARGs during subsequent distribution. Mechanistically, DWTPs obtain direct and inderect ARGs reduction through DNA damage and interception of host bacterias of ARGs. Thus, escaping of intracellular ARGs to extracellular environment, induced by DWTPs, should be advoided. This review provides the theoretical support for developping efficient reduction technologies of ARGs. Future study should focus on ARGs controlling in terms of transmissibility or persistence through DWTPs due to their biological related nature and ubiquitous presence of biofilm in the treatment unit.     

稻田土壤氧化亚氮产生潜势、反硝化功能基因丰度和群落结构的垂向分布

土壤中氧化亚氮（N₂O）的释放量占全球N₂O释放总量的60%.其中，稻田土壤是N₂O最主要的释放源.反硝化过程是稻田土壤N₂O生成的主要微生物过程之一.本研究选取广东韶关稻田垂向土壤（0~100 cm）为研究对象，通过乙炔抑制剂法测定了N₂O产生潜势和反硝化潜势，并利用针对特异性功能基因的实时荧光定量和高通量测序技术分别分析反硝化功能基因丰度和反硝化微生物群落结构.结果显示：0~10 cm深度的土壤样品N₂O产生潜势最高，可达（0.020±0.0035）μg·g^-1·h^-1.反硝化功能基因中，nirK基因的丰度峰值（（1.51±0.0015）×10⁸ copies·g^-1）出现在0~10 cm深度，而nosZ和nirS基因的丰度峰值（（4.29±0.0015）×10⁷ copies·g^-1和（8.86±0.0010）×10⁷ copies·g^-1）均出现在10~20 cm深度.稻田垂向土壤中N₂O产生潜势和相关的反硝化功能基因（nosZ、nirK和nirS）丰度均随土壤深度的增加而逐渐降低.其中在所有深度的土壤样品中nirK基因的丰度均高于nirS.基于nirK基因的高通量测序结果发现慢生根瘤菌（Bradyrhizobium）的相对丰度最高（44.06%±6.14%，n=6）.相关性分析表明，稻田土壤中N₂O产生潜势与环境因子（TN、TC和含水率）、反硝化功能基因丰度以及慢生根瘤菌（Bradyrhizobium），罗河杆菌属（Rhodanobacter）和亚硝化螺菌属（Nitrosospira）的相对丰度呈正相关.上述结果表明稻田土壤中环境因子和反硝化功能基因丰度影响了N₂O产生潜势的垂向分布.     

Antibiotic resistance genes in manure-amended paddy soils across eastern China: Occurrence and influencing factors

• Manure fertilization resulted in antibiotic residues and increased metal contents. • The tet and sul genes were significantly enhanced with manure fertilization. • Soil physicochemical properties contributed to 12% of the variations in ARGs. • Soil metals and antibiotics co-select for ARGs. Pig manure, rich in antibiotics and metals, is widely applied in paddy fields as a soil conditioner, triggering the proliferation of antibiotic resistance genes (ARGs) in soil. However, comprehensive studies on the effects of manure fertilization on the abundance of ARGs and their influencing factors are still insufficient. Here, pig manure and manure-amended and inorganic-amended soils were collected from 11 rice-cropping regions in eastern China, and the accumulation of antibiotics, metals, and ARGs was assessed simultaneously. The results showed that manure fertilization led to antibiotic residues and increased the metal content (i.e., Zn, Cu, Ni, and Cr). Tetracycline and sulfonamide resistance genes (tetM, tetO, sul1, and sul2) were also significantly enhanced with manure fertilization. According to variance partitioning analysis, the most important factors that individually influenced ARGs were soil physicochemical properties, accounting for 12% of the variation. Significant correlations between soil nutrients and ARGs indicated that manure application enhanced the growth of resistant microorganisms by supplying more nutrients. Metals and antibiotics contributed 9% and 5% to the variations in ARGs, respectively. Their co-occurrence also increased the enrichment of ARGs, as their interactions accounted for 2% of the variation in ARGs. Interestingly, Cu was significantly related to most ARGs in the soil (r = 0.26–0.52, p<0.05). Sulfapyridine was significantly related to sul2, and tetracycline resistance genes were positively related to doxycycline. This study highlighted the risks of antibiotic and ARG accumulation with manure fertilization and shed light on the essential influencing factors of ARGs in paddy soils.     

The Harm Principle and Genetically Modified Food

It is suggested that the Harm Principle can be viewedas the moral basis on which genetically modified (GM) food iscurrently regulated. It is then argued (a) that the concept ofharm cannot be specified in such a manner as to render the HarmPrinciple a plausible political principle, so this principlecannot be used to justify existing regulation; and (b) that evenif the Harm Principle were a plausible political principle, itcould not be used alone in the regulation of GM food, since itdoes not express a concern for the expected benefits of suchfood.