Biosorption of heavy metals by Bacillus thuringiensis strain OSM29 originating from industrial effluent contaminated north Indian soil

The study was navigated to examine the metal biosorbing ability of bacterial strain OSM29 recovered from rhizosphere of cauliflower grown in soil irrigated consistently with industrial effluents. The metal tolerant bacterial strain OSM29 was identified as Bacillus thuringiensis following 16S rRNA gene sequence analysis. In the presence of the varying concentrations (25–150 mgl⁻¹) of heavy metals, such as cadmium, chromium, copper, lead and nickel, the B. thuringiensis strain OSM29 showed an obvious metal removing potential. The effect of certain physico-chemical factors such as pH, initial metal concentration, and contact time on biosorption was also assessed. The optimum pH for nickel and chromium removal was 7, while for cadmium, copper and lead, it was 6. The optimal contact time was 30 min. for each metal at 32 ± 2 °C by strain OSM29. The biosorption capacity of the strain OSM29 for the metallic ions was highest for Ni (94%) which was followed by Cu (91.8%), while the lowest sorption by bacterial biomass was recorded for Cd (87%) at 25 mgl⁻¹ initial metal ion concentration. The regression coefficients obtained for heavy metals from the Freundlich and Langmuir models were significant. The surface chemical functional groups of B. thuringiensis biomass identified by Fourier transform infrared (FTIR) were amino, carboxyl, hydroxyl, and carbonyl groups, which may be involved in the biosorption of heavy metals. The biosorption ability of B. thuringiensis OSM29 varied with metals and was pH and metal concentration dependent. The biosorption of each metal was fairly rapid which could be an advantage for large scale treatment of contaminated sites.     

Nickel Bioremediation Potential of Bacillus thuringiensis KUNi1 and Some Environmental Factors in Nickel Removal

The present study endeavors to isolate a nickel (Ni)-resistant bacterial strain from an industrial waste–contaminated soil sample and to characterize the strain with a view to identify it and to assess its ability to remove Ni from the medium or detoxify it. The final objective is to use the strain as an agent to bioremediate Ni contamination. As an outcome, a Ni-resistant bacterial strain (KUNi1) had been isolated from such a soil that could tolerate a maximum of 7.5 and 10 mM Ni concentrations, depending on the type of medium used. The strain also showed multimetal resistance. It was found to be resistant to zinc (Zn), copper (Cu), cobalt (Co), and cadmium (Cd). However, the degree of resistance to the individual metal was variable, as determined by assessing the minimum inhibitory concentration (MIC) of each metal against the strain. The order of resistance was Ni > Zn = Cu = Co > Cd. The strain removed a significant percentage (82%) of Ni from the medium during in vitro culture, whereas dead cell mass had an insignificant role in Ni removal. The quantum of Ni removal by the strain was interfered with when the other metals (Zn, Cu, Co, and Cd) were present either singly with Ni or in combination with other metals. However, the degree of interference varied with individual metal. The factors that influenced the quantum of Ni removal were ambient pH, initial cell density, and presence of other toxic metals. The strain was identified as Bacillus thuringiensis on the basis of its biochemical characteristics and 16s rDNA sequence analysis.     

Biomonitoring with Honeybees of Heavy Metals and Pesticides in Nature Reserves of the Marche Region (Italy)

The aim of this study was to carry out biomonitoring with honeybees (Apis mellifera L.) to assess the presence of pesticides and heavy metals (cadmium, chromium, nickel, lead) in all of the ten nature reserves of the Marche Region (central–eastern Italy). The study was carried out during the spring and summer seasons when the honeybees were active, over 3 years (2008–2010). Twenty-two colonies of honeybees bred in hives were used. Samples of live and dead honeybees and of honey were collected from 11 sampling stations from May to October in each year. No pesticide pollution was found. Significant differences in heavy metal concentrations were found among years, months and sites, and in particular situations. The analysis reveals that high heavy-metal concentrations occurred exclusively in live honeybees. For the seasonal averages, the most detected heavy metal was chromium, which exceeded the threshold more often than for the other elements, followed by cadmium and lead; nickel never exceeded the threshold. The data are discussed with an evaluation of the natural and anthropic sources taken from the literature and from local situations that were likely to involve heavy metal pollution.     

Bioremediation of Heavy Metals in Liquid Media Through Fungi Isolated from Contaminated Sources

Wastewater particularly from electroplating, paint, leather, metal and tanning industries contain enormous amount of heavy metals. Microorganisms including fungi have been reported to exclude heavy metals from wastewater through bioaccumulation and biosorption at low cost and in eco-friendly way. An attempt was, therefore, made to isolate fungi from sites contaminated with heavy metals for higher tolerance and removal of heavy metals from wastewater. Seventy-six fungal isolates tolerant to heavy metals like Pb, Cd, Cr and Ni were isolated from sewage, sludge and industrial effluents containing heavy metals. Four fungi (Phanerochaete chrysosporium, Aspegillus awamori, Aspergillus flavus, Trichoderma viride) also were included in this study. The majority of the fungal isolates were able to tolerate up to 400 ppm concentration of Pb, Cd, Cr and Ni. The most heavy metal tolerant fungi were studied for removal of heavy metals from liquid media at 50 ppm concentration. Results indicated removal of substantial amount of heavy metals by some of the fungi. With respect to Pb, Cd, Cr and Ni, maximum uptake of 59.67, 16.25, 0.55, and 0.55 mg/g was observed by fungi Pb3 (Aspergillus terreus), Trichoderma viride, Cr8 (Trichoderma longibrachiatum), and isolate Ni27 (A. niger) respectively. This indicated the potential of these fungi as biosorbent for removal of heavy metals from wastewater and industrial effluents containing higher concentration of heavy metals.     

A rapid screening method for the isolation of metal-accumulating microorganisms

Summary An agar plate screening method was developed for the rapid isolation of heavy metal-accumulating microorganisms and preliminary estimation of their biosorption capacity. The test is based on the visulaization and interpretation of the metal distribution between agar and colonies by chemical preciptitation with hydrogen sulphide or ammonium sulphide. The heavy metals silver, thallium, lead, copper, nickel and cadmium have been tested successfully. The efficiency of the method is demonstrated for isolating silver-accumulating bacterian and estimating silver biosorption capacity.     

Effect of Increasing Concentrations of Heavy Metals on the Growth of Barley and Wheat Seedlings

The tolerance to increasing doses of lead and cadmium salts on the growth and survival of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) seedlings were studied. Seedlings grown under controlled conditions were treated with dilute (0.001–0.005 mM) solutions of either lead nitrate or cadmium bromide for 1, 4, or 7 days. Subsequently, they were incubated for 7 days in solutions of the same compounds, but at sublethal or lethal concentrations (0.05–10 mM). Plant pretreatment with low concentrations of heavy metals induced an increase in their tolerance to the metals, because pretreated plants could tolerate heavy metals at high concentrations. It is concluded that plant tolerance to increasing concentrations of heavy metals is related to the activation of protective and adaptive processes in their tissues.     

Accumulation of selected heavy metals by different genotypes of Salix

The aim of this study was to assess the accumulation of seven heavy metals (lead, cadmium, copper, zinc, chrome, nickel and cobalt). The investigations were conducted on twelve genotypes of willows which grow in the Potasze Forest Division Salicarium. The analysis facilitated quantification of concentrations of selected metals in plants and their comparison in relation to sorption ability of each willow genotype. Simultaneously the studies allowed us to demonstrate essential differentiation of metal size sorption within the species Salix purpurea and in relation to the other genotypes. The results confirm the complexity of factors influencing the efficiency of heavy metal accumulation by willow; they indicate increasing ion absorption in the case of some metals, while the accumulation of other heavy metal ions was limited.     

Detection and Analysis of 12 Heavy Metals in Blood and Hair Sample from a General Population of Pearl River Delta Area

To detect the content of 12 heavy metals in blood and hair sample from a general population of Pearl River Delta area, and to analyze the influence of duration of residence, gender, age, smoking and drinking on the heavy metal content. Use inductively coupled plasma mass spectrometry to detect the content of 12 heavy metals lead (Pb), mercury (Hg), cadmium (Cd), aluminum (Al), arsenic (As), copper (Cu), chrome (Cr), manganese (Mn), nickel (Ni), zinc (Zn), tin (Sn) and antimony (Sb) in blood and hair samples of a total of 50 subjects from a general population, collected by multistage stratified cluster random sampling method. The geometric mean of heavy metal content in blood samples of general population (μg/L): blood aluminum 214.00; blood chrome 92.82; blood manganese 21.43; blood nickel 20.59; blood copper 0.67; blood zinc 11.50; blood arsenic 0.55; blood cadmium 2.45; blood tin 0.00; blood antimony 1.92; blood lead 158.84; and blood mercury 1.19. The geometric mean of heavy metal content in hair samples of general population (μg/g): hair aluminum is 84.65; hair chrome 0.00; hair manganese 2.44; hair nickel 0.61; hair copper 28.49; hair zinc 136.65; hair arsenic 0.75; hair cadmium 0.46; hair tin 1.04; hair antimony 0.05; hair lead 8.97; and hair mercury 0.69. Some heavy metals were correlated with duration of residence, gender, age, smoking and drinking. This was the first time that simultaneously detecting heavy metal content in blood and hair was used to analyze the internal heavy metal burden in resident population of Pearl River Delta area. These data can serve as reference for further research.     

Comparisons of nine heavy metals in salt gland and liver of greater scaup (Aythya marila), black duck (Anas rubripes) and mallard (A. platyrhynchos)

Levels of nine heavy metals were measured in the livers and salt glands of greater scaup (Aythya marila), black duck (Anas rubripes) and mallard (A. platyrhynchos) from Raritan Bay, New Jersey to determine if the functioning avian salt gland concentrates heavy metals. Heavy metals examined were cadmium, cobalt, chromium, copper, lead, mercury, manganese, nickel and zinc. Heavy metal levels varied significantly by species and tissue for chromium, copper, lead, and manganese, and by tissue for cobalt, mercury, nickel and zinc. In comparing tissues cobalt was higher in the salt glands than in livers of all three species; chromium and nickel were higher in the salt gland than liver for mallard and black duck; and lead, manganese and zinc were higher in the liver than the salt gland in greater scaup. Generally metal levels were higher in the salt gland for mallard and black duck, and in the liver for greater scaup.     

Blockade of heavy metals accumulation in Chlorella vulgaris cells by 24-epibrassinolide

This study was conducted on the influence of 24-epibrassinolide (24-epiBL) mixed with varying concentrations of heavy metals (copper, lead, cadmium, zinc) upon the growth and accumulation of these heavy metals in the cell of the alga Chlorella vulgaris Beijerinck (Chlorophyceae). Heavy metals at the concentration of 10^–3 M, alone or mixed with 24-epiBL, showed a lethal effect on C. vulgaris. At metal concentrations of 10^–6–10^–4 M, a combination with 24-epiBL appeared to have a stronger stimulatory effect on a number of cells than a single metal (a stronger inhibitory effect). 24-EpiBL at the concentration of 10^–8 M in combination with heavy metals (in the range 10^–6–10^–4 M) blocked metal accumulation in algal cells. 24-EpiBL has an anti-stress effect on C. vulgaris contaminated by heavy metals. The inhibitory effect on metal accumulation of 24-epiBL mixed with different heavy metals was arranged in the following order: zinc > cadmium > lead > copper. This process is correlated with the stimulation of growth of C. vulgaris. The stimulatory effect of 24-epiBL mixed with heavy metals leading to an increased pH in the medium (5.28–6.20) was significantly higher than the impact due to the increased acidity in the medium due to metals alone (pH 3.10–5.85). Lower pH increased the toxicity of heavy metals in C. vulgaris cells.     

Effect of Increasing Concentrations of Lead and Cadmium on Cucumber Seedlings

The effect of lead and cadmium on biomass accumulation of cucumber seedlings (Cucumis sativus L.) as well as the contents of abscisic acid (ABA), free proline and soluble proteins in leaves were studied. Seedlings were subjected to lead nitrate or cadmium bromide in low concentrations (1 – 5 µM) for 1, 4 or 7 d, and then to the action of the same substances in high concentrations (500 – 1000 µM). The pretreatments of the seedlings with heavy metals in low concentrations enabled them to tolerate the subsequent high concentrations of cadmium and lead without injury. The plant responses to heavy metal treatment were accompanied by the accumulation of ABA, free proline and soluble proteins in leaf tissues.     

蛋白酶分泌菌对重金属胁迫的反应

本文研究了Pb、Zn、Cu和Cd对3种蛋白酶产生菌：碱性地衣芽孢杆菌2709(Bacillus licheniformis 2709)、中性枯草杆菌1.398(Bacillus subtilis1.398)和酸性宇佐美曲霉537(Aspergillus usamii 537)生长及其酶活性的影响, 并采用生长抑制皿分析(GIPA)方法针对3种菌株在Pb、Zn、Cu、Cd不同胁迫浓度下的生长量进行打分, 分析其耐性与抗性指标(MTC与MIC)。结果表明4种重金属在超过一定临界浓度后, 对3种菌株的生长和蛋白酶活性均产生了较大的抑制作用。碱性蛋白酶对4种重金属均具有较大的适应性, 其次是中性蛋白酶对Zn和Cd具有一定的适应性, 而酸性蛋白酶对4种重金属均表现出被抑制状态。3种菌株对Pb和Zn耐性与抗性最高(2.0 mmol/L~6.0 mmol/L), 其次是对Cd也具有一定的抗性(0.5 mmol/L~0.75 mmol/L)。     

蛋白酶分泌菌对重金属胁迫的反应

本文研究了Pb、zn、cu和Cd对3种蛋白酶产生菌:碱性地衣芽孢杆菌2709(Bacilluslicheniformis 2709)、中性枯草杆菌1.398(Bacillus subtilis1.398)和酸性宇佐美曲霉537(Aspergillususamii 537)生长及其酶活性的影响,并采用生长抑制皿分析(GIPA)方法针对3种菌株在Pb、zn、Cu、Cd不同胁迫浓度下的生长量进行打分,分析其耐性与抗性指标(MTC与MIC).结果表明4种重金属在超过一定临界浓度后,对3种菌株的生长和蛋白酶活性均产生了较大的抑制作用.碱性蛋白酶对4种重金属均具有较大的适应性,其次是中性蛋白酶对Zn和Cd具有一定的适应性.而酸性蛋白酶对4种重金属均表现出被抑制状态.3种菌株对Pb和Zn耐性与抗性最高(2.0 mmol/L～6.0 mmol/L),其次是对Cd也具有一定的抗性(0.5 mmol/L～0.75 mmol/L).     

Uptake of lead by bacteria isolated from industrial effluents and their potential use in bioremediation of wastewater

Due to rising populations and human activities, heavy metals (HM) toxicity has become a serious problem for all life forms. The present study deals with isolating and identifying lead-resistant bacteria from contaminated wastewater of tanneries effluents. Two isolated strains were identified as Bacillus cereus (ID1), and Bacillus sp. (ID3), and both strains resisted a 25 mM concentration of Lead nitrate (Pb (NO₃)₂). After four days of treatment, Bacillus cereus (ID1) showed 80% lead uptake, and Bacillus sp. (ID3) showed 88%. Lead uptake was confirmed by Energy dispersive X-Ray (EDX) analysis. Fourier transform infrared spectroscopy (FTIR) showed that structural alterations had occurred in functional groups of the treated samples compared to the controls. Our research indicates that these Bacillus strains may be useful in bioremediating heavy metals from polluted environments. Further investigation into the processes involved in the uptake and homeostasis of heavy metals by these strains is required, as is the identification of the genes and enzymes responsible for Pb-bioremediation.     

MALDI-TOF-MS and 16S rRNA characterization of lead tolerant metallophile bacteria isolated from saffron soils of Kashmir for their sequestration potential

Toxic metal contamination in soils due industrialization is nowadays a concern to the scientists worldwide. The current study deals with the evaluation of response and tolerance by isolated metallophilic bacteria in different lead concentrations (100 ppm to 1000 ppm). By taking optical densities of the isolates, the minimum inhibitory concentration (MIC) of Pb²⁺ were determined.16S rRNA and MALDI-TOF MS were used for the identification of the bacteria. Total of 37 isolates were observed, among them 04 (Staphylococcus equorum, Staphylococcus warneri, Bacillus safensis and Bacillus thuringiensis), isolated were detected having efficacy of Pb²⁺tolerance and sequestration at varying MIC. Furthermore, B. thuringiensis was observed to have highest (900 ppm) tolerance for lead and lowest (500 ppm) for Staphylococcus warneri. Moreover, the highest (65.3%) sequestration potential has been observed for B. thuringiensis and least (52.8%) for S. warneri. The tolerance and sequestration potential properties of these isolated species can be utilised to exterminate heavy metals and reduce their toxicity from the contaminated environment.     

Accumulative phases for heavy metals in limnic sediments

Data from mechanical concentrates of recent sediments indicate that clay minerals, clay-rich aggregates and heavy minerals are the major carriers of heavy metals in detrital sediment fractions. Hydrous Fe/Mn oxides and carbonates and sulfides, in their specific environments, are the predominant accumulative phases for heavy metals in autochthonous fractions. Sequential chemical extraction techniques permit the estimation of characteristic heavy metal bonding forms: exchangeable metal cations, easily reducible, moderately reducible, organic and residual metal fractions, whereby both diagenetic processes and the potential availability of toxic compounds can be studied. The data from lakes affected by acid precipitation indicate that zinc, cobalt and nickel are mainly released from the easily reducible sediment fractions and cadmium from organic phases. In contrast at pH 4.4, neither lead nor copper seem to be remobilized to any significant extent. Immobilization by carbonate precipitation seems to provide an effective mechanism for the reduction of dissolved inputs 9f metals such as zinc and cadmium in pH-buffered, hard water systems.     

单一与复合污染条件下两种敏感性植物对Cd、Zn、Pb的吸收效应

为了进一步研究镉、锌、铅 3种重金属元素间的相互作用以及对植物吸收重金属能力的影响 ,在模拟单一重金属污染试验研究的基础上 ,采用正交回归设计方案 ,研究了 Cd、Zn、Pb复合污染情况下紫花苜蓿和披碱草两种敏感性植物对 3种重金属的吸收效应。结果表明 ,在单一污染条件下 ,镉元素对紫花苜蓿生长的影响大于锌、铅 ,铅元素对披碱草生长的影响大于锌、镉 ;紫花苜蓿对于镉的吸收累积显著高于披碱草 ,植物内镉元素浓度最高达到 1 0 88.5 mg/kg,而披碱草对于铅元素的吸收则高于紫花苜蓿 ,植物内铅元素浓度最高达到 1 3 4 5 .5 mg/kg。在复合污染条件下 ,两种植物对铅、锌和铅、镉的吸收在不同浓度范围内分别存在存在着协同效应和拮抗效应 ;同时两种植物对锌、镉元素在实验涉及浓度范围内都存在着拮抗效应。这对于深入研究复合污染条件下重金属的土壤环境化学行为 ,对植物的综合毒性以及不同植物对重金属的吸收累积效应等 ,具有一定的参考意义     

Metallothionein induction in human peripheral blood lymphocytes by heavy metals

Human peripheral blood lymphocytes have the capacity to produce metallothioneins (MTs) as a protective response to cadmium exposure. To define the range of metal species inducing lymphocyte MTs, cellular proteins synthesized after exposure to each of 11 heavy metals were analyzed by gel electrophoresis. Toxic metals such as cadmium, mercury and silver were found to induce thioneins (apoproteins of MTs) at relatively low concentrations (maximum at approximately 10 microM), whereas less toxic metals such as zinc, copper and nickel were inductive at relatively high concentrations (maximum at approximately 200 microM). Tin, lead, iron, cobalt, and manganese did not induce thioneins. The heavy metal specificity of MT induction in the lymphocyte resembles that in the liver, and the regulatory mechanism of MT production seems to be similar in both of these tissues. In the cells exposed to highly toxic metals such as cadmium and mercury, expression of cytotoxicity (represented by decline of cysteine uptake) was remarkable at the metal concentrations higher than those saturating thionein induction, supporting the protective role of MTs against heavy metals.     

大肠杆菌拓扑异构酶I结合重金属的特性及功能影响

【背景】大肠杆菌拓扑异构酶Ⅰ(Escherichia coli topoisomerase I,E.coli TopA)在DNA复制、转录、重组和基因表达调控等过程发挥关键作用。研究表明E.coli TopA只有结合锌离子才具有活性,然而E.coli TopA能否结合其他金属离子尤其是重金属离子,以及结合其他金属后是否具有活性,目前仍不清楚。【目的】探究大肠杆菌拓扑异构酶Ⅰ是否结合环境中常见重金属离子,研究重金属离子结合E.coli TopA蛋白后对其活性的影响。【方法】在分别添加有锌、钴、镍、镉、铁、汞、砷、铬、铅、铜离子的M9基础培养中表达、纯化出E.coli TopA蛋白,并对纯化得到的蛋白用电感耦合等离子体质谱仪进行相应金属离子含量的测定;利用表达E.coli TopA锌指结构的突变体蛋白鉴定重金属离子的结合位点;通过体外超螺旋DNA松弛实验测定不同金属结合E.coli TopA的拓扑异构酶活性;通过测定蛋白内源性荧光推测不同金属结合E.coli TopA的空间构象差异。【结果】E.coli TopA在体内除了能结合锌和铁之外,还能够结合钴、镍、镉3种离子,但是不能结合汞、砷、铬、铅、铜离子。钴、镍、镉结合形式的E.coli TopA,每个蛋白分子最多可以结合3个相应的金属离子,他们与TopA蛋白的结合位点也是位于3个锌指结构域,而且每个锌指结构域结合1个金属离子。此外,E.coli TopA结合钴、镍、镉离子后,其DNA拓扑异构酶活性并未受到影响,可能是由于钴、镍、镉离子结合形式的E.coli TopA蛋白,其空间构象与锌结合形式相比并未发生显著变化。【结论】由于DNA拓扑异构酶在维持细胞正常生理功能中发挥关键作用,研究表明E.coli TopA的功能不会受到常见重金属的干扰(不结合或者结合后活性无影响),这也有可能是大肠杆菌在进化过程中产生的对抗环境中重金属离子毒害作用的一种自我保护和耐受机制,具有重要的生理意义。