Comparative toxicity of silver nanoparticles and silver ions to Escherichia coli

With the increase in silver(Ag)-based products in our lives, it is essential to test the potential toxicity of silver nanoparticles(Ag NPs) and silver ions(Ag ions) on living organisms under various conditions. Here, we investigated the toxicity of Ag NPs with Ag ions to Escherichia coli K-12 strain under various conditions. We observed that both Ag NPs and Ag ions display antibacterial activities, and that Ag ions had higher toxicity to E. coli K-12 strain than Ag NPs under the same concentrations. To understand the toxicity of Ag NPs at a cellular level, reactive oxygen species(ROS) enzymes were detected for use as antioxidant enzymatic biomarkers. We have also studied the toxicity of Ag NPs and Ag ions under various coexistence conditions including: fixed total concentration, with a varied the ratio of Ag NPs to Ag ions; fixed the Ag NPs concentration and then increased the Ag ions concentration; fixed Ag ions concentration and then increasing the Ag NPs concentration.Exposure to Ag NPs and Ag ions clearly had synergistic toxicity; however, decreased toxicity(for a fixed Ag NPs concentration of 5 mg/L, after increasing the Ag ions concentration) to E. coli K-12 strain. Ag NPs and Ag ions in the presence of L-cysteine accelerated the bacterial cell growth rate, thereby reducing the bioavailability of Ag ions released from Ag NPs under the single and coexistence conditions. Further works are needed to consider this potential for Ag NPs and Ag ions toxicity across a range of environmental conditions.Environmental Significance Statement: As silver nanoparticles(Ag NPs)-based products are being broadly used in commercial industries, an ecotoxicological understanding of the Ag NPs being released into the environment should be further considered. Here, we investigate the comparative toxicity of Ag NPs and silver ions(Ag ions) to Escherichia coli K-12 strain, a representative ecotoxicological bioreporter. This study showed that toxicities of Ag NPs and Ag ions to E. coli K-12 strain display different relationships when existing individually or when coexisting, and in the presence of L-cysteine materials. These findings suggest that the toxicology research of nanomaterials should consider conditions when NPs coexist with and without their bioavailable ions.     

基于大肠杆菌的CellSense生物传感器毒性分析性能研究

采用聚碳酸酯膜直接固定法制备并优化了大肠杆菌（E.coli Top10）CellSense生物传感器微生物电极,探讨了其在重金属和有机污染物生物急性毒性分析中的应用性能.结果表明,基于对数生长后期和稳定期E.coli微生物电极的CellSense生物传感器具有良好的毒性分析性能,基于衰减期E.coli菌株的CellSense生物传感器毒性分析的稳定性和灵敏性降低;CellSense生物传感器测试得Hg²⁺、Cu²⁺、Zn²⁺、邻氯苯酚和对硝基苯酚对E.coli的EC50分别为0.6、3.1、5.8、180和94 μg/mL,制备的E.coli微生物电极在冰箱中4℃保存2个月,仍能很好地满足毒性分析的需要.     

接合子细胞强化对生物反应器降解2，4-D效应研究

研究了接合性质粒pJP4在2株纯菌E．coliDH5α、Alcaligenes sp．及好氧颗粒污泥混合菌群中的水平转移情况,并以获得pJP4质粒的接合子Alcaligenes sp．：：pJP4为强化菌种,考察了接合子细胞强化对好氧颗粒反应器和生物膜反应器中难降解有机物2,4-二氯苯氧乙酸（2,4-D）的去除效应．结...     

高级氧化联合生物活性炭工艺深度净化污水中PPCPs研究进展

污水处理厂传统的二级生化处理对药品及个人护理用品(Pharmaceutical and Personal Care Products, PPCPs)等新兴污染物的去除率较低, PPCPs随出水排放会给生态环境带来较大的风险,并会经过生物富集最终危害到人体健康,因此需要通过进一步的深度净化以削减其风险.本文综述了常见PPCPs在污水处理系统的分布特征及生态风险,阐述了高级氧化工艺(Advanced oxidation processes, AOPs)、生物活性炭工艺(Biological activated carbon, BAC)以及高级氧化联合生物活性炭工艺(AOPs-BAC)深度净化PPCPs的净化原理,在此基础上,综述了AOPs-BAC工艺对污水中PPCPs的深度净化效果及主要影响因素,并探讨了AOPs-BAC工艺对污水中PPCPs的风险削减能力,为污水中PPCPs深度净化工艺的研发及PPCPs的生态风险控制提供了参考.     

基于CellSense生物传感器的垃圾渗滤液毒性分析

采用基于大肠杆菌(E.coli)的CellSense生物传感器,对上海某垃圾填埋场渗滤液处理系统垃圾渗滤液原液(1号)、兼性塘(2号)、曝气氧化塘(3号)、矿化垃圾生物床(4号)和FeC内电解(5号)各处理单元的水质毒性进行跟踪分析.结果表明,在该垃圾渗滤液的处理过程中,由于渗滤液的基质作用和难降解有机物生成的毒性中间产物等的影响,处理工艺中部分单元的水质毒性出现升高现象.CellSense生物传感器分析得上述1~5号单元的水质综合毒性分别为90%(EC10)、80%(EC30)、60%(EC50)、80%(EC50)和2%(EC50),毒性分析结果与对应的COD和氨氮等指标无明显相关性.     

胶质气体泡沫气浮分离含Cu(Ⅱ)废水的试验研究

用阴离子表面活性剂十二烷基硫酸钠(SDS)制备胶质气体泡沫并将之引入浮选柱,以胶质气体泡沫为浮选载体并通入常规浮选气泡对预先装入浮选柱的模拟含Cu(Ⅱ)废水进行浮选分离实验,考察了pH值、铜离子初始浓度、SDS用量和絮凝剂的添加对Cu(Ⅱ)去除率的影响。实验结果表明,采用胶质气体泡沫与常规柱浮选气泡相结合的方法处理含Cu(Ⅱ)废水,铜离子去除率可达99%以上。     

氯代苯胺对斑马鱼的急性毒性及3D-QSAR分析

研究了2-氯-4-硝基苯胺、4-氯-3-硝基苯胺、2-氯-5-硝基苯胺、2,4-二氯苯胺、3,4-二氯苯胺、2,5-二氯苯胺、2,3-二氯苯胺对斑马鱼(Brachydanio rerio)的96 h急性毒性,96 h LC50分别为6.99,2.58,8.63,7.79,6.08,5.23,0.49 mg/L.运用三维定量结构活性相关模型(3D-QSAR)对这些化合物的毒性效应和构效关系进行了分析和评价,估算毒性值与实际观测值相关性较好,相关系数R2＝0.907.      

污水中大肠杆菌的酶联免疫检测方法研究

以城市污水处理厂二沉池出水为检测目标,比较了夹心法和直接法2种酶联免疫反应方式,分析包被抗体和酶标抗体浓度、菌液预处理等因素对检测灵敏度的影响,确定了ELISA的最佳工作条件.结果表明,检测大肠杆菌的线性区间为10CFU/mL～6×10⁴CFU/mL,最低检测限达到10CFU/mL.与传统检测方法相比,该技术具有操作简单,节省时间和费用,反应灵敏度高等优点.     

混凝/微滤工艺用于青草沙水源水厂的生产废水回用研究

本文通过混凝/微滤工艺对青草沙水源水水厂的生产废水开展了回用处理研究,分析了常规污染物、微量有机物、金属离子的去除规律和消毒副产物生成趋势.结果表明,混凝预处理可以有效减缓膜污染;组合工艺对悬浮态物质如颗粒物、细菌、大肠杆菌等有较好的去除效果,去除率均达85%以上;对溶解性成分,尤其是Al和微量有机物去除效果不佳,去除率均低于20%.生产废水膜过滤后相同的消毒剂浓度时消毒副产物的生成趋势高于砂滤池和炭滤池出水.研究认为,青草沙水源水厂的生产废水净化后回用的最佳回用点是砂滤池前或活性炭生物滤池前.     

Construction of WCB-11: A novel phiYFP arsenic-resistant whole-cell biosensor

The prediction and assessment of environmental pollution by arsenic are important preconditions of advocating environmental protection and human health risk assessment.A yellow fluorescent protein-based whole-cell biosensor for the detection of arsenite and arsenate was constructed and tested.An arsenic-resistant promoter and the regulatory gene arsR were obtained by PCR from the genome of Escherichia coli DH5α,and phiYFP was introduced into E.coli DH5α as a reporter gene to construct an arsenic-resistant whole-cell biosensor(WCB-11) in which phiYFP was expressed well for the first time.Experimental results demonstrated that the biosensor has a good response to arsenic and the expression of phiYFP.When strain WCB-11 was exposed to As 3+ and As 5+,the expression of yellow fluorescence was time-dependent and dose-dependent.This engineered construct is expected to become established as an inexpensive and convenient method for the detection of arsenic in the field.     

Zebrafish embryo toxicity of 15 chlorinated, brominated, and iodinated disinfection by-products

Disinfection to protect human health occurs at drinking water and wastewater facilities through application of non-selective oxidants including chlorine. Oxidants also transform organic material and form disinfection by-products (DBPs), many of which are halogenated and cyto- and genotoxic. Only a handful of assays have been used to compare DBP toxicity, and researchers are unsure which DBP(s) drive the increased cancer risk associated with drinking chlorinated water. The most extensive data set employs an in vitro model cell, Chinese hamster ovary cells. Traditionally, most DBP research focuses on the threat to human health, but the effects on aquatic species exposed to DBPs in wastewater effluents remain ill defined. We present the developmental toxicity for 15 DBPs and a chlorinated wastewater to a model aquatic vertebrate, zebrafish. Mono-halogenated DBPs followed the in vivo toxicity rank order: acetamides > acetic acids > acetonitriles ~ nitrosamines, which agrees well with previously published mammalian in vitro data. Di- and tri-halogenated acetonitriles were more toxic than their mono-halogenated analogues, and bromine- and iodine-substituted DBPs tended to be more toxic than chlorinated analogues. No zebrafish development effects were observed after exposure to undiluted or non-concentrated, chlorinated wastewater. We find zebrafish development to be a viable in vivo alternative or confirmatory assay to mammalian in vitro cell assays.     

抗生素和纳米银对大肠杆菌耐药性的联合效应

以大肠杆菌（E.coli）为模式生物,研究了磺胺类抗生素（SAs）和纳米银（AgNPs）在单一或联合作用下对RP4质粒接合转移效应及E.coli突变效应的影响,并对联合作用方式进行了判别,基于分子对接技术和线性回归分析,探讨了两种效应的机制及其与毒性效应的关系.结果表明,在较低浓度范围内,所测12种SAs以及AgNPs在单一或联合暴露下对接合转移和突变均有促进作用,12组SAs-AgNPs混合物对接合转移频率促进率峰值的最大值和最小值分别为105.32%和46.96%,对突变体促进率峰值的最大值和最小值分别为1410.25%和238.38%.此外,SAs和AgNPs联合暴露对RP4质粒接合转移效应主要表现为协同作用,对E.coli突变效应主要表现为拮抗作用,且接合转移效应、突变效应与毒性效应之间具有良好的相关性.     

抗生素和纳米银对大肠杆菌耐药性的联合效应

以大肠杆菌（E.coli）为模式生物,研究了磺胺类抗生素（SAs）和纳米银（AgNPs）在单一或联合作用下对RP4质粒接合转移效应及E.coli突变效应的影响,并对联合作用方式进行了判别,基于分子对接技术和线性回归分析,探讨了两种效应的机制及其与毒性效应的关系.结果表明,在较低浓度范围内,所测12种SAs以及AgNPs在单一或联合暴露下对接合转移和突变均有促进作用,12组SAs-AgNPs混合物对接合转移频率促进率峰值的最大值和最小值分别为105.32%和46.96%,对突变体促进率峰值的最大值和最小值分别为1410.25%和238.38%.此外,SAs和AgNPs联合暴露对RP4质粒接合转移效应主要表现为协同作用,对E.coli突变效应主要表现为拮抗作用,且接合转移效应、突变效应与毒性效应之间具有良好的相关性.     

我国淡水环境中卤乙酸类消毒副产物的预测无效应浓度研究

新型冠状病毒肺炎（COVID-19,简称“新冠肺炎”）疫情期间,消毒剂超量使用,导致大量DBPs（disinfection by-products,消毒副产物）进入自然水体,可能对水生态环境产生不良影响.以5种HAAs（卤乙酸类）消毒副产物（一氯乙酸、二氯乙酸、三氯乙酸、一溴乙酸和二溴乙酸）为研究目标,基于筛选的本土水生生物的毒性数据,采用欧盟《风险评价技术指导文件》中的评估系数法和平衡分配法分别推导了5种HAAs在水体和沉积物两种介质中的PNEC（预测无效应浓度）值.结果表明:5种HAAs对水生生物的急、慢性毒性大小顺序均为一溴乙酸>一氯乙酸>二氯乙酸>三氯乙酸>二溴乙酸;5种HAAs（一氯乙酸、二氯乙酸、三氯乙酸、一溴乙酸和二溴乙酸）的PNEC_w（水体的预测无效应浓度）分别为0.025、0.030、0.060、0.016和1.956 mg/L,PNEC_s（沉积物的预测无效应浓度）分别为0.021、0.026、0.057、0.013和1.679 mg/kg（以湿质量计）.研究显示,污水处理厂出水中排放的DBPs对水生态环境可能造成潜在的风险和危害,应加强对污水处理厂出水中5种HAAs的监测和去除,从而减少排入到自然水体中的HAAs含量.      

基于枯草芽孢杆菌微生物传感器的毒性分析

采用枯草芽孢杆菌(Bacillus subtilis)为指示生物的微生物传感器毒性分析系统,对重金属(Hg2+、Cu2+、Zn2+、Cr6+、Cd2+、Pb2+和Co2+)、有机污染物[邻氯苯酚(2-CP)、2,4-二氯酚(2,4-DCP)、邻硝基酚(2-NP)、对硝基酚(4-NP)、四环素和十二烷基苯磺酸钠]及石油废水等的生物急性毒性进行分析.结果表明,对数生长后期和稳定期的Bacillussubtilis微生物传感器具有良好的毒性分析性能,Cd2+、Zn2+、Cr6+、Cu2+、Hg2+、Pb2+对Bacillus subtilis的EC50分别为47.3,10.9,14.0,2.6,0.8,100.1mg/L,Co2+的EC30为56.6mg/L,2-CP、2,4-DCP、2-NP、4-NP、四环素和十二烷基苯磺酸钠的EC50分别为559.6,450.8,588.5,487.0,121.3,558.9mg/L,该微生物传感器能真实反映石油废水的毒性情况.     

石化工业园区有毒废水来源识别研究

针对石化废水对综合污水处理厂的毒性冲击问题,采用耗氧速率抑制试验评价不同石化废水对活性污泥的毒性,评价对象包括石化工业园区内不同生产装置和装置内不同生产节点的废水.试验发现废水的有机质含量与毒性效应之间没有直接的相关性,并不能单从废水的有机质含量预测其毒性.同时,研究中针对活性污泥敏感性在不同批次试验之间的差异问题,将各废水对活性污泥的毒性数据转化为标准毒性物质3,5-二氯苯酚的浓度,提高了数据之间的可比性.在此基础上,根据废水流量和对应3,5-二氯苯酚浓度,计算废水对应标准毒性物质质量排放负荷,作为评价废水毒性排放贡献的指标.对不同装置和节点石化废水的毒性贡献进行排序,有效识别了该石化工业园区内有毒废水的产生来源,为从生产源头控制废水毒性提供有效指导.     

CEH3段漂白废水的毒性研究

采用发光细菌法对某造纸厂的漂白废水(CEH3段)进行了毒性研究,其中C段废水的毒性最大,其EC50为24.67属于强毒级别;E段、H段以及CEH混合废水的EC50分别为94.10%、98.39%、53.79%,分别属于微毒、微毒、毒性级别;C毒性排放负荷约占废水总毒性排放负荷的78%左右。实验结果表明,漂白废水的毒性排放负荷较大,纸浆废水的TEF(毒性排放因子)约为106.52TU·m3/t,相当于每吨纸浆含10.65gHgCl2的毒性,故对其治理不容忽视。     

Degradation of 2,6-di-tert-butylphenol by an isolated high-efficiency bacterium strain

An aerobic bacterium strain, F-3-4, capable of effectively degrading 2,6-di-tert-butylphenol(2,6-DTBP), was isolated and screened out from an acrylic fiber wastewater and the biofilm in the wastewater treatment facilities. This strain was identified as Alcaligenes sp. through morphological, physiological and biochemical examinations. After cultivation, the strain was enhanced by 26.3% in its degradation capacity for 2,6-DTBP. Results indicated that the strain was able to utilize 2,6-DTBP, lysine, lactamine, citrate, n-utenedioic acid and malic acid as the sole carbon and energy source, alkalinize acetamide, asparagine, L-histidine, acetate, citrate and propionate,but failed to utilize glucose, D-fructose, D-seminose, D-xylose, sedne and phenylalanine as the sole carbon and energy source. The optimal growth conditions were determined to be: temperature 37℃, pH 7.0, inoculum size 0.1% and shaker rotary speed 250 r/min. Under the optimal conditions, the degradation kinetics of 2,6-DTBP with an initial concentration of 100 mg/L was studied. Results indicated that 62.4% of 2,6-DTBP was removed after 11 d. The degradation kinetics could be expressed by Eckenfelder equation with a half life of 9.38 d. In addition, the initial concentration of 2,6-DTBP played an important role on the degradation ability of the strain. The maximum initial concentration of 2,6-DTBP was determined to be 200 mg/L. Above this level, the strain was overloaded and exhibited significant inhibition.     

Purified terephthalic acid wastewater biodegradation and toxicity

The biodegradation and toxicity of the purified terephthalic acid（PTA） processing wastewater was researched at NJYZ pilot with the fusant strain Fhhh in the carrier activated sludge process（ CASP）. Sludge loading rate（SLR） for Fhhh to COD of the wastewater was 1.09 d^-1 and to PTA in the wastewater was 0.29 d^-1. The results of bioassay at the pilot and calculation with software Ebis3 showed that the 48h-LC50 （median lethal concentration） to Daphnia magna for the PTA concentration in the wastewater was only 1/10 of that for the chemical PTA. There were .5 kinds of benzoate pollutants and their toxicities existing in the wastewater at least. The toxicity parameter value of the pure chemical PTA cannot be used to predicate the PTA wastewater toxicity. The toxicity of the NJYZ PTA wastewater will be discussed in detail in this paper.     

光合细菌和螺旋藻对啤酒废水的净化与利用研究

应用ＰＳＢ将啤酒废水中的有机质降解处理为无机质，用甲壳絮凝沉降除去ＰＳＢ后加入螺旋藻进行培养。小型动态模拟实验结果表明ＰＳＢ和螺旋藻不仅能高效地净化啤酒废水。