基因工程菌大肠杆菌JM109富集废水中镍离子的研究

利用通过基因工程技术所构建的在细胞内同时表达出高特异性镍转运蛋白和金属硫蛋白的基因工程菌富集水体中的镍离子。菌体细胞对Ni²⁺的富集速率很快,富集过程满足Langmuir等温线模型。与原始宿主菌相比,经基因改造的基因工程菌不仅最大镍富集容量增加了5倍多,而且对pH值、离子强度的变化及其它共存重金属离子的影响都呈现出更强的适应性。相比而言,Na⁺、Ca²⁺、Cd²⁺、Pb²⁺的影响较小,但Mg²⁺、Hg²⁺和Cu²⁺所引起的负面效应较大。进一步的实验表明基因工程菌对Ni2+的富集行为不需要外加营养物质。     

Differentiating Between Direct (Physiological) and Food-Chain Mediated (Bioenergetic) Effects on Fish in Metal-Impacted Lakes

The objectives of this field project were to test relationships between the physiological and population status of indigenous fish and (a) ecological factors (habitat quality, food resources), (b) toxicological factors (ambient and tissue metal concentrations), and (c) metal detoxification factors (metallothionein induction and subcellular metal partitioning). The sentinel species, yellow perch (YP: Perca flavescens), was collected from lakes with contrasting metal levels located on the Canadian Precambrian Shield, downwind and downstream from metal smelters. In lakes at the high end of our exposure gradient, metals (Cu, Ni, and especially Cd) accumulate in YP to concentrations well above background tissue values; increases in tissue Zn concentrations were much more modest, despite the existence of a very marked gradient in ambient [Zn]. Metal accumulation in YP is accompanied by metallothionein induction, but all evidence to date suggests that metal detoxification by metallothionein is incomplete. Indeed, direct effects of metal toxicity are detected at multiple levels of biological organization, from effects at the cellular level, to effects in organs and tissues, to individuals and populations, in a pattern linked to accumulated metal concentrations (i.e., along the contamination gradient). In addition to direct or physiological effects, we also documented indirect, food-web-mediated effects of metals on YP in the most contaminated lakes. The most common indication of such indirect effects on YP is severely stunted growth coupled with a high degree of zooplankton dependence throughout their life.     

Heavy metal accumulation in rice (Oryza sativa) near electronic waste dumps and related human health risk assessment

This research was conducted to assess heavy metal contamination in the environment and within Oryza sativa. The translocation factors (TFs) and bioaccumulation factors (BAFs) for heavy metals in O. sativa and estimated daily intake (EDI) and health risk index (HRI) were measured. The samples were analyzed for heavy metals using inductively coupled plasma optical emission spectrometry (ICP-OES). Pb and Cr concentrations in water samples within and near the electronic-waste dumping area exceeded water quality standards for surface water sources from the Pollution Control Department in the Ministry of Natural Resources and Environment of Thailand (PCD). The Pb concentration in soil samples within the area also exceeded soil quality standards for habitat and agriculture from PCD. Most of the metals were highly concentrated in roots, except for Mn which has the highest concentration in leaves. Pb concentrations in rice grains exceeded the FAO/WHO standard (0.2 mg/kg). The average TF values for heavy metals from the soil to roots, roots to stems, stems to leaves, and stems to grains were Mn > Pb > Ni > Cr, Mn > Cr > Ni > Pb, Ni > Pb > Mn > Cr, and Pb > Ni > Cr > Mn, respectively. The average BAF values in O. sativa were Mn > Ni > Pb > Cr. The EDI for Cr, Pb, Mn, and Ni via O. sativa consumption were 6.19, 6.02, 370.57, and 3.80 µg/kg/day, respectively. The HRI for Cr, Pb, Mn, and Ni via O. sativa consumption were 0.30, 1.50, 2.60, and 0.002, respectively.     

Enantiomerization and Enantioselective Bioaccumulation of Metalaxyl in Tenebrio molitor Larvae

The enantiomerization and enantioselective bioaccumulation of metalaxyl by a single dose of exposure to Tenebrio molitor larvae under laboratory condition were studied by high‐performance liquid chromatography tandem mass spectroscopy (HPLC‐MS/MS) based on a ChiralcelOD‐3R [cellulosetris‐tris‐(3, 5‐dichlorophenyl‐carbamate)] column. Exposure of enantiopure R‐metalaxyl and S‐metalaxyl in Tenebrio molitor larvae exhibited significant enantiomerization, with formation of the R enantiomers from the S enantiomers, and vice versa, which might be attributed to the chiral pesticide catalyzed by a certain enzyme in Tenebrio molitor larvae. Enantiomerization was not observed in wheat bran during the period of 21 d. In addition, bioaccumulation of rac‐metalaxyl in Tenebrio molitor larvae was enantioselective with a preferential accumulation of S‐metalaxyl. These results showed that enantioselectivity was caused not only by actual degradation and metabolism but also by enantiomerization, which was an important process in the environmental fate and behavior of metalaxyl enantiomers. Chirality 26:88–94, 2014. © 2013 Wiley Periodicals, Inc.     

一株耐锌真菌CTB430-1分离鉴定及其富集特性

从某锌尾砂坝土壤中筛选分离、纯化得到一株对锌具有较强抗性的菌株,命名为CTB430-1.对菌株进行形态观察、生理生化试验,采用ITS基因序列分析并构建系统发育树,鉴定该菌为黄曲霉（Aspergillus flavus）.研究其对Zn（Ⅱ）抗性和富集特性.结果表明：Zn（Ⅱ）对该菌株的最低抑菌浓度为800 mg/L;菌株对Zn（Ⅱ）的富集量在250 mg/L时达到最大,为40.37 mg/g;采用扫描和透射电镜观察富集前后菌丝体表面形态和内部结构变化,表明Zn（Ⅱ）毒害作用可能导致生长中菌丝表面结构破坏,CTB430-1富集Zn（Ⅱ）由表面吸附和胞内富集两部分组成.     

Natural and induced cadmium-accumulation in poplar and willow: Implications for phytoremediation

Potentially poplars and willows may be used for the in situ decontamination of soils polluted with Cd, such as pasturelands fertilised with Cd-rich superphosphate fertiliser. Poplar (Kawa and Argyle) and willow (Tangoio) clones were grown in soils containing a range (0.6–60.6 μg g⁻¹ dry soil) of Cd concentrations. The willow clone accumulated significantly more Cd (9–167 μg g⁻¹ dry matter) than the two poplar clones (6–75 μg g⁻¹), which themselves were not significantly different. Poplar trees (Beaupré) sampled in situ from a contaminated site near the town of Auby, Northern France, were also found to accumulate significant quantities (up to 209 μg g⁻¹) of Cd. The addition of chelating agents (0.5 and 2 g kg⁻¹ EDTA, 0.5 g kg⁻¹ DTPA and 0.5 g kg⁻¹NTA) to poplar (Kawa) clones caused a temporary increase in uptake of Cd. However, two of the chelating agents (2 g kg⁻¹ EDTA and 0.5 g kg⁻¹ NTA) also resulted in a significant reduction in growth, as well as abscission of leaves. If the results obtained in these pot experiments can be realised in the field, then a single crop of willows could remove over 100 years worth of fertiliser-induced Cd contamination from pasturelands. This revised version was published online in June 2006 with corrections to the Cover Date.     

Stereoselective bioaccumulation,transformation, and toxicity of triadimefon in Scenedesmus obliquus

In this study the stereoselective bioaccumulation and transformation of triadimefon and the toxicity of triadimefon and its metabolite triadimenol to the green algae Scenedesmus obliquus were studied. In growth inhibition experiments, triadimenol was more toxic than triadimefon, and (1S,2R)‐triadimenol, which has the largest fungicidal activity, presented the highest toxicity to the algae. In bioaccumulation experiments, triadimefon was rapidly taken up by algae cells, and the decrease in the concentration of triadimefon was accompanied by an increase in triadimenol. The transformation of S‐(+)‐ triadimefon was faster than that of the R‐(−)‐enantiomer, resulting in four triadimenol stereoisomers at different forming rates: B2 (1S, 2S) > B1 (1R, 2R) > A2 (1S, 2R) > A1 (1R, 2S). Thus, it is necessary to explore the enantioselective toxicology and ecological fate of these chiral pesticides in an environmental risk assessment. Also, their metabolites should be paid specific attention to since they may pose higher ecological risks.     

Efficient Uptake of Cesium Ions by Rhodococcus Cells

Bacteria of the genus Rhodococcus were found to be able to accumulate cesium by means of active transport and nonspecific sorption on the cell surface structures. The maximum removal (up to 97%) of cesium from a medium supplemented with ammonium acetate was observed at 28°C, pH 7.8–8.6, and an equimolar content (0.2 mM) of potassium and cesium ions in the medium. The most active cesium-accumulating rhodococcal strains may be useful in biological treatment of industrial wastewaters contaminated with radionuclides.     

Renal bioaccumulation of trace elements in urban and rural Sri Lankan populations: A preliminary study based on post mortem tissue analysis

IntroductionEnvironmental pollution, especially by toxic trace elements, is a global health concern. Heavy metals such as Cadmium (Cd), Arsenic (As) and Lead (Pb) are associated with numerous disorders and are considered by some as an aetiological factor for the Chronic Kidney Disease (CKDu¹) epidemic in Sri Lanka. This study explores patterns of bioaccumulation of six trace elements in kidneys obtained during forensic autopsies from urban and rural regions in Sri Lanka.MethodsKidney samples obtained from one urban district (n = 13) and three rural districts (n = 18) were lyophilized, microwave digested and profiled by ICP-MS techniques.Results and DiscussionThe mean age of the sampled population was 47.9 ± 11.3 yrs. Median (IQR) for Cd, As, Pb, Cr, Zn and Se were, 14.67(8.04–22.47) μg/g, 0.44(0.29–0.56) μg/g, 0.11(0.07–0.30) μg/g, 0.15(0.1096–0.3274), 25.55(17.24–39.35) μg/g and 0.52(0.37−0.84) μg/g, respectively. Cd, Zn and Se levels were significantly higher (p < 0.05) among the urban samples compared to that of the rural group. Zn and Se levels were higher among younger age groups. As, Pb and Cr did not show any significant differences between the two cohorts nor any correlations with age.ConclusionThis population-specific baseline study provides an insight into the differences in exposure to toxic trace elements and essential elements between urban and rural populations. Residents in CKDu affected rural districts did not appear to be at risk of toxic heavy metal exposure, however their renal bioaccumulation of nephroprotective essential elements was lower than urban residents.     

Fate of heavy metals in vertical subsurface flow constructed wetlands treating secondary treated petroleum refinery wastewater in Kaduna,Nigeria

This study examined the performance of pilot-scale vertical subsurface flow constructed wetlands (VSF–CWs) planted with three indigenous plants, i.e. Typha latifolia, Cyperus alternifolius, and Cynodon dactylon, in removing heavy metals from secondary treated refinery wastewater under tropical conditions. The T. latifolia-planted VSF–CW had the best heavy metal removal performance, followed by the Cyperus alternifolius-planted VSF–CW and then the Cynodon dactylon-planted VSF–CW. The data indicated that Cu, Cr, Zn, Pb, Cd, and Fe were accumulated in the plants at all the three VSF–CWs. However, the accumulation of the heavy metals in the plants accounted for only a rather small fraction (0.09–16%) of the overall heavy metal removal by the wetlands. The plant roots accumulated the highest amount of heavy metals, followed by the leaves, and then the stem. Cr and Fe were mainly retained in the roots of T. latifolia, Cyperus alternifolius, and Cynodon dactylon (TF < 1), meaning that Cr and Fe were only partially transported to the leaves of these plants. This study showed that VSF–CWs planted with T. latifolia, Cyperus Alternifolius, and Cynodon dactylon can be used for the large-scale removal of heavy metals from secondary refinery wastewater.