Per-and polyfluoroalkyl substances（PFASs） are ubiquitous in sludge and water from waste water treatment plants, as a result of their incorporation in everyday products and industrial processes. In this study, we mea...Per-and polyfluoroalkyl substances（PFASs） are ubiquitous in sludge and water from waste water treatment plants, as a result of their incorporation in everyday products and industrial processes. In this study, we measured several classes of persistent PFASs,precursors, transformation intermediates, and newly identified PFASs in influent and effluent sewage water and sludge from three municipal waste water treatment plants in Sweden, sampled in 2015. For sludge, samples from 2012 and 2014 were analyzed as well.Levels of precursors in sludge exceeded those of perfluoroalkyl acids and sulfonic acids（PFCAs and PFSAs）, in 2015 the sum of polyfluoroalkyl phosphoric acid esters（PAPs） were 15–20 ng/g dry weight, the sum of fluorotelomer sulfonic acids（FTSAs） was 0.8–1.3 ng/g,and the sum of perfluorooctane sulfonamides and ethanols ranged from non-detected to 3.2 ng/g. Persistent PFSAs and PFCAs were detected at 1.9–3.9 ng/g and 2.4–7.3 ng/g dry weight, respectively. The influence of precursor compounds was further demonstrated by an observed substantial increase for a majority of the persistent PFCAs and PFSAs in water after waste water treatment. Perfluorohexanoic acid（PFHxA）, perfluorooctanoic acid（PFOA）, perfluorohexane sulfonic acid（PFHxS）, and perfluorooctane sulfonic acid（PFOS）had a net mass increase in all WWTPs, with mean values of 83%, 28%, 37% and 58%,respectively. The load of precursors and intermediates in influent water and sludge combined with net mass increase support the hypothesis that degradation of precursor compounds is a significant contributor to PFAS contamination in the environment.展开更多
文摘【目的】探索大肠埃希氏菌(Escherichia coli,E.coli)FtsZ(236-245)结构域两性螺旋特性对FtsZ组装和FtsZ-FtsA相互作用的影响。【方法】利用分子克隆和定点突变技术,构建FtsZ及其突变体表达载体,亲和纯化获得相应目标蛋白;通过同源重组和Pl转导构建QN23-QN29菌株;利用活细胞成像观察FtsZ及其突变体的胞内定位特点;膜蛋白分离和Western blot分析FtsZ突变体的膜结合特性变化;非变性胶分离和体外聚合分析检测定点突变对FtsZ单体组装特性的影响;免疫沉淀和Far Western blot实验检测FtsZ/FtsZ~*-FtsA间的相互作用。【结果】FtsZ^(E234A/K)和FtsZ^(E241A/K)突变体的功能活性降低、备突变体在E.coli内不能正确定位和形成功能性Z环;E237A/K和E241A/K位点突变致备突变体聚合能力降低、FtsZ*-FtsA的相互作用减弱和FtsZ的膜结合特性变化。【结论】E237和E241是影响FtsZ(236-245)区域两性螺旋特性和FtsZ组装及FtsZ-FtsA相互作用的重要氨基酸。
基金funded by the Swedish Environmental Protection Agency
文摘Per-and polyfluoroalkyl substances（PFASs） are ubiquitous in sludge and water from waste water treatment plants, as a result of their incorporation in everyday products and industrial processes. In this study, we measured several classes of persistent PFASs,precursors, transformation intermediates, and newly identified PFASs in influent and effluent sewage water and sludge from three municipal waste water treatment plants in Sweden, sampled in 2015. For sludge, samples from 2012 and 2014 were analyzed as well.Levels of precursors in sludge exceeded those of perfluoroalkyl acids and sulfonic acids（PFCAs and PFSAs）, in 2015 the sum of polyfluoroalkyl phosphoric acid esters（PAPs） were 15–20 ng/g dry weight, the sum of fluorotelomer sulfonic acids（FTSAs） was 0.8–1.3 ng/g,and the sum of perfluorooctane sulfonamides and ethanols ranged from non-detected to 3.2 ng/g. Persistent PFSAs and PFCAs were detected at 1.9–3.9 ng/g and 2.4–7.3 ng/g dry weight, respectively. The influence of precursor compounds was further demonstrated by an observed substantial increase for a majority of the persistent PFCAs and PFSAs in water after waste water treatment. Perfluorohexanoic acid（PFHxA）, perfluorooctanoic acid（PFOA）, perfluorohexane sulfonic acid（PFHxS）, and perfluorooctane sulfonic acid（PFOS）had a net mass increase in all WWTPs, with mean values of 83%, 28%, 37% and 58%,respectively. The load of precursors and intermediates in influent water and sludge combined with net mass increase support the hypothesis that degradation of precursor compounds is a significant contributor to PFAS contamination in the environment.
