Fate of antibiotics and antibiotic resistance genes in a full-scale restaurant food waste treatment plant: Implications of the roles beyond heavy metals and mobile genetic elements

Is our food safe and free of the crisis of antibiotics and antibiotic resistance(AR)?And will the derived food waste(FW) impose AR risk to the environment after biological treatment? This study used restaurant FW leachates flowing through a 200 tons-waste/day biological treatment plant as a window to investigate the fate of antibiotics and antibiotic-resistance genes(ARGs) during the acceptance and treatment of FW. Sulfonamides(sulfamethazine, sulfamethoxazole) and quinolones(ciprofloxacin, enrofloxacin, ofloxacin) were detected during FW treatment, while tetracyclines, macrolides and chloramphenicols were not observable. ARGs encoding resistance to sulfonamides, tetracyclines and macrolides emerged in FW leachates.Material flow analysis illustrated that the total amount of antibiotics(except sulfamethazine) and ARGs were constant during FW treatment processes. Both the concentration and total amount of most antibiotics and ARGs fluctuated during treatment, physical processes(screening, centrifugation, solid–liquid and oil–water separation) did not decrease antibiotic or ARGs concentrations or total levels permanently; the affiliated wastewater treatment plant appeared to remove sulfonamides and most ARGs concentrations and total amount. Heavy metals Ni,Co and Cu were important for disseminating antibiotics concentrations and MGEs for distributing ARGs concentrations. Humic substances(fulvic acids, hydrophilic fractions), C-associated and N-associated contents were essential for the distribution of the total amounts of antibiotics and ARGs. Overall, this study implied that human food might not be free of antibiotics and ARGs, and FW was an underestimated AR pool with various determinants. Nonetheless, derived hazards of FW could be mitigated through biological treatment with well-planned daily operations.     

混凝沉淀-UF工艺去除二级出水中ARGs效能研究

为了研究混凝沉淀-UF工艺对城市污水处理厂二级出水中ARGs（抗生素抗性基因）去除的影响,以PACl（聚合氯化铝）和PFS（聚合硫酸铁）作为混凝剂,采用qPCR（实时荧光定量聚合酶链式反应）和EEM（三维荧光光谱）等分析混凝沉淀-UF工艺对ARGs的削减及其影响因素.结果表明:① PACl、PFS投加量（分别以Al、Fe计,下同）分别为0.85、0.50 mmol/L时,与直接UF工艺相比,混凝沉淀-UF工艺对水中各类ARGs的去除量高2~3个数量级,其中PACl-UF工艺的效果更好,去除量为2.51~3.52个数量级;对水中DOC（溶解性有机碳）、富里酸类及溶解性微生物代谢产物的去除效果更好,DOC去除率由18%升至36%.②直接UF、PACl-UF、PFS-UF 3种工艺膜进、出水的线性拟合结果显示,ARGs浓度与ρ（DOC）、16S rDNA浓度均呈显著正相关.研究显示,混凝沉淀-UF工艺可以有效去除二级出水中的ARGs,且有机物、16S rDNA的去除有助于ARGs的削减.      

梅花鹿养殖场抗生素抗性基因分布特征

梅花鹿养殖是近年来我国南方地区出现的新兴养殖业.为探究梅花鹿养殖对养殖环境抗生素抗性基因的影响,采用高通量荧光定量PCR研究了抗生素抗性基因在养殖场区对照土壤、梅花鹿新鲜粪便、梅花鹿粪便堆肥产物和施用堆肥菜地土壤中的分布、丰度和多样性.结果表明,抗性基因的绝对丰度梅花鹿粪便堆肥产物梅花鹿新鲜粪便施用堆肥菜地土壤养殖场区对照土壤,抗生素抗性基因在4种环境样品中具有不同分布格局;梅花鹿养殖场环境中抗性基因丰度与可移动基因元件丰度显著相关(P0.05),表明可移动基因元件可能加快了抗性基因的水平转移过程,促进了抗性基因的迁移、传播和富集,加剧了养殖环境抗生素抗性基因污染.     

环丙沙星对膜生物反应器中微生物群落及抗性基因的影响

用膜生物反应器(membrane bioreactor,MBR)处理含环丙沙星(ciprofloxacin,CIP)的合成废水,考察了不同CIP进水浓度(0、5、10、15 mg·L-1)下MBR的微生物群落特征和抗性基因丰度的变化.结果表明,随着进水中CIP浓度从0 mg·L-1增加至15 mg·L-1,变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes)仍保持为优势菌门,相对丰度比例分别为57.5%和12.7%;红环菌科(Rhodocyclaceae)、Chitinophagaceae和丛毛单胞菌科(Comamonadaceae)被选择成为优势菌科,比例分别为29.96%、5.44%和6.60%;Methyloversatilis、Ferruginibacter、动胶菌属(Zoogloea)和丛毛单胞菌属(Comamonas)被选择成为优势菌属,比例分别为21.70%、7.56%、5.24%和4.15%;Chao1、ACE、Shannon指数逐渐降低和Simpson指数逐渐升高,表明MBR污泥中微生物丰富度和多样性均降低;亚硝化单胞菌属(Nitrosomonas)、硝化螺旋菌属(Nitrospira)、产碱菌属(Alcaligenes)和硝化杆菌属(Nitrobacter)相对丰度减少,使得氨氮去除率降低.CIP抗性基因(CIP-ARGs)分析表明,当MBR在CIP投加浓度为5 mg·L-1下运行至第33 d时,反应器中的gyr A、gyr B和par C基因相对丰度较CIP投加初期增加,加大了抗药风险.     

铜尾矿库区土壤重金属及微生物重金属抗性基因空间分异特征

重金属污染的长期存在,使环境中的微生物保持并不断强化其自身重金属抗性.为了研究长期污染场地重金属污染水平和土壤中微生物重金属抗性之间的关系,本文以山西省灵丘县刁泉铜矿尾矿库区及其周边为研究对象,研究了不同立地条件下土壤重金属含量特征以及重金属抗性基因的丰度与分布,采用Hakanson潜在生态风险指数法对该区域的生态环境风险进行了评估,并对重金属及重金属抗性基因进行相关分析.结果表明:①研究区土壤重金属污染严重,7种重金属Cr、Ni、Zn、As、Cd、Cu、Pb含量均超过山西土壤背景值,单因子潜在生态危害程度顺序基本上为CdPbCuAsNiZnCr.②尾矿库区存在不同程度的生态危害,尾矿坝、草地属于很强生态危害,林地、农田处于强生态危害,不同样地间的潜在生态风险顺序为草地尾矿坝农田林地.③相对丰度较高的重金属抗性基因主要是针对Cu、As的抗性,针对Cu抗性以cop基因为主,针对As抗性以ars基因为主.④除copA基因与重金属之间存在显著相关性外,其他重金属抗性基因与重金属含量之间的相关性不显著.     

珠江口典型水产养殖区抗生素抗性基因污染的初步研究

使用普通PCR和荧光定量PCR方法对珠江口典型水产养殖区水和沉积物中3种磺胺类、7种四环素类、1种喹诺酮类抗生素抗性基因(antibiotic resistance genes,ARGs)和1种整合子基因进行了定性和定量研究.结果表明,除tetW外,所有其他ARGs在珠江口养殖区中均被检出,其中sul1、sul2和int1的检出率为100%.相同养殖模式下,养殖时间越长ARGs的相对含量越高,表明ARGs具有累积效应;不同养殖模式池塘中ARGs的含量存在差异,表明养殖模式可能影响ARGs的含量与分布.int1相对含量与sul1和ARGs总量之间均存在显著相关性(P<0.05),表明int1在ARGs的水平传播中起着非常重要的作用.此外,珠江口水产养殖区沉积物中抗生素浓度与ARGs总量存在显著相关性(P<0.05),说明水产养殖区中抗生素残留是诱导养殖区ARGs的主要因素.     

木聚糖酶基因xynB在不同大肠杆菌表达系统中的表达比较

从黑曲霉(Aspergillus niger)nl-1中克隆获得木聚糖酶基因xynB.该基因全长745 bp,含有67 bp内含子,与公布的黑曲霉xynB基因有较高的同源性.将PCR扩增的木聚糖酶成熟肽基因和含有信号肽的基因分别连接到表达载体肠杆菌Top10 F’、DH10B和两种BL21宿主中获得重组菌株.通过IPTG诱导,xynB基因在重组菌株中获得特异性表达.表达产物以胞内可溶性蛋白和不溶性包涵体形式存在.诱导4 h,重组菌株pTrc-99a-xynB[BL21 condon plus(DE3)]表达量最高,胞内酶活达到299 IU/L.重组质粒pTrc-99a-xyn B(S)在不同宿主胞内和胞外均能分泌目的蛋白,诱导10 h,胞外酶活pTrc-99a-xynB(S)[BL21 condon plus(DE3)]达到347 IU/L.而pET-20b-xynB(S)在两种BL21宿主中均不表达.经SDS-PAGE分析,以pTrc-99a和pET-20b作为表达载体时,重组蛋白相对分子质量分别约为45×103和30×103.与pET-20b相比,pTrc-99a以及自身信号肽的引导更有利于重组木聚糖酶的表达.     

黑曲霉耐热木聚糖酶XYNB在毕赤酵母中的高效表达

高比活木聚糖酶的高效表达是进一步提高木聚糖酶发酵效价、降低生产成本的有效途径.将黑曲霉木聚糖酶基因XynB(不含信号肽)克隆到分泌型表达载体pPIC9K上,线性化后电击转化巴斯德毕赤酵母GS115,G418和PCR鉴定的阳性转化子经0.5%甲醇、在28℃诱导表达.SDS-PAGE分析表明,该蛋白相对分子质量为20×103左右.优化的诱导表达条件为,每隔12 h添加0.5%的甲醇,发酵5 d后,比活达4 757 U/mg;其最适温度为55℃,最适pH为5.0,80℃处理30min后仍有74%的残余酶活.     

紫色土丘陵区畜禽养殖场土壤中抗生素抗性基因分布特征

鉴于紫色土高垦殖丘陵区土壤中抗生素抗性基因的潜在生态环境风险,本研究采用高通量荧光定量PCR技术,分析了抗生素抗性基因在不同类型畜禽养殖场(养猪场、养鸡场和养牛场)土壤中的丰度和多样性.结果表明,3种养殖场土壤中共检出79种抗生素抗性基因和5种可移动基因元件,其中多重耐药类基因是养殖场土壤中丰度最高的耐药基因.不同养殖场土壤中抗生素抗性基因的丰度和多样性均表现为养鸡场和养猪场样品高于养牛场土壤,且3种养殖场土壤样品中的抗性基因表现出不同的类别分布特征.养殖场土壤中较高的可移动基因元件丰度,及其与抗生素抗性基因丰度显著的相关性(P0. 05)说明,可移动基因元件可能促进了抗生素抗性基因在养殖场土壤中的迁移和扩散.     

Estrogenic activities of two synthetic pyrethroids and their metabolites

Synthetic pyrethroids(SPs) are among the most common pesticides in current use,and so far,several SPs have been assessed for their potential estrogenicities by various methods.Previous studies have shown that the estrogenicities partly come from their metabolites.Although considerable information is available with respect to the metabolism and environmental degradation of SPs,little is known about the estrogenicities of the metabolites.In this study,permethrin(PM) and β-cypermethrin(CP),as well as their metabolites(3-phenoxybenzoic alcohol(PBCOH),3-phenoxybenzaldehyde(PBCHO) and 3-phenoxybenzoic acid(PBCOOH) were evaluated for their estrogenic activities in the MCF-7 human breast carcinoma cell line.In the MCF-7 cell proliferation assay,PM and CP exhibited significant estrogenic activities at 10-7 mol/L,comparable to 17β-estradiol(E2 ) of 10-9 mol/L,with the relative proliferative effect ratios of 55.4% and 56.3%,respectively.The real-time quantitative polymerase chain reaction(qRT-PCR) results confirmed the estrogenicities of PM and CP with significant alteration of pS2 and ERα mRNA levels observed at 10-6 mol/L.For the three major metabolites,PBCOH and PBCOOH exhibited estrogenic activities in all assays,while no significant estrogenic responses was observed for PBCHO compared to the vehicle control.In particular,PBCOH had even slightly stronger estrogenic activity than its parent compounds,indicating that metabolism may be one of the reasons for the estrogenicities of the SPs.Given the widespread use of SPs,the toxicological effects of parent compounds and their metabolites should be taken into consideration in the risk assessment of SPs.