Recovery of gold from thiourea solutions using microorganisms

The recovery of gold from gold-thiourea solutions using various types of waste biomass was investigated. All organisms tested, namely, Saccharomyces cerevisiae, Spirulina platensis and Streptomyces erythraeus removed gold rapidly from gold–thiourea solutions. The process of gold accumulation was pH-dependent for Saccharomyces ceresvisiae and Streptomyces erythraeus and independent of pH in the case of Spirulina platensis. Of all strains of microorganisms examined, Spirulina platensis had the highest affinity and capacity for gold even at low pH values. Thus, all three microorganisms tested for their ability to recover gold from gold–thiourea solutions can therefore be used in biotechnological applications, especially Spirulina platensis which has the highest binding capacity for gold at low pH values. © Rapid Science 1998     

Simultaneous determination of Zn,Cd, Pb,and Cu in urine of patients with blackfoot disease using anodic stripping voltammetry

Blackfoot disease (BFD) is an endemic peripheral vascular disorder resulting in gangrene of the lower extremities, especially the feet, among residents in a limited area on the southwest coast of Taiwan. In the present study, the concentrations of zinc, cadmium, lead, and copper in urine of BFD patients with matched normal controls are investigated by differential pulse anodic stripping voltammetry (DPASV) on a hanging mercury drop electrode (HMDE). The analytical results indicate that urinary copper, cadmium, and lead of the BFD patients are significantly higher than those of the controls. In addition, the patients showed a significantly lower concentration of zinc in the urine than the normal controls. The possible connection of these elements with the etiology of the disease is discussed.     

油橄榄叶中橄榄苦苷的分离纯化

考察了6种不同大孔树脂对橄榄苦苷的吸附,筛选出吸附选择性好的D101大孔吸附树脂为实验材料.得到的D101大孔树脂的最佳吸附条件:试样上样质量浓度41.06[J].,流速5 mL/min,50％乙醇溶液洗脱,洗脱液用量260mL,树脂可以反复使用.经大孔树脂富集后,橄榄苦苷的纯度可达55％以上,再经葡聚糖凝胶精纯化后,可达76％以上.     

地木耳多糖的提取与纯化研究

对地木耳采用水提醇沉法获得的地木耳多糖粗提取物,采用Sevage法脱蛋白质、醇沉,干燥得粗多糖,进一步用DEAE-52纤维素柱层析分离纯化,用纸色谱和琼脂糖凝胶电泳对洗脱组分进行纯度鉴定。结果表明：Sevage法脱蛋白7次可脱除94%的蛋白质,多糖得率为13.75%。DEAE-52纤维素柱层析后得到10种组分,浓缩干燥后得到白色粉末状多糖组分,每个组分经过纯度鉴定后均为单一的多糖。选择水和NaC l溶液为洗脱剂的温和条件分离纯化多糖效果较好。     

Selective recovery of uranium and thorium ions from dilute aqueous solutions by animal biopolymers

Selective actinide ion recovery from dilute, aqueous, multication waste streams is an important problem. The recovery of uranium (U) and thorium (Th) by various animal biopolymers was examined. Of four species of biopolymers tested, a high uptake of uranium and thorium was found in hen eggshell membrane (ESM) and silk proteins, with the maximum uranium and thorium recovery exceeding 98% and 79%, respectively. The uptake of U and Th was significantly affected by the pH of the solution. The optimum pH values were 6 and 3 for the uptake of U and Th, respectively. The effect of temperature differed with the metal. The uptake of U decreased with increasing temperature (30–50°C), whereas the Th uptake increased with increasing temperature. Selective recovery of U and Th from dilute aqueous binary and multimetal solutions was also examined. ESM and silk proteins tested were effective and selective for removing each metal by controlling the pH and temperature of the solution. In multimetal systems, the order of sorption of ESM proteins was preferential: U > Cu > Cd > Mn > Pb > Th > Ni > Co > Zn at pH 6 and Th > U > Cu > Pb > Cd > Mn > Co > Ni = Zn at pH 3. These biopolymers appear to have potential for use in a commercial process for actinide recovery from actinide-containing wastewater.     

Effects of copper,zinc, and cadmium ions on the production of phosphate from phytic acid by the phytase system in spruce forest soil

Summary The hydrolysis of phosphate from phytic acid by the acid soil phytase system was reduced in the presence of metal ions. Copper was most effective in this respect — zinc and cadmium were less inhibitory. Binding to metals did not completely inhibit the hydrolysis of phytic acid. At higher metal concentrations, where binding to other soil constituents, like humic acids, interfered less, the inhibition of the phytase activity was stronger than that of acid phosphatase.     

Differential pulse anodic voltammetric determination of pantoprazole in pharmaceutical dosage forms and human plasma using glassy carbon electrode

Pantoprazole is used as an anti-ulcer drug through inhibition of H(+), K(+)-adenosine 5(')-triphosphatase in gastric parietal cells. It reduces the gastric acid secretion regardless of the nature of stimulation. The use of differential pulse voltammetry for the determination of pantoprazole in pharmaceutical dosage forms and human plasma using a glassy carbon electrode has been examined. The best voltammetric response was reached for a glassy carbon electrode in Britton-Robinson buffer solution of pH 5.0 submitted to a scan rate of 20.0 mVs(-1) and a pulse amplitude of 50.0 mV. This electroanalytical procedure was able to determine pantoprazole in the concentration range 6.0 x 10(-6)-8.0 x 10(-4)M. Precision and accuracy of the developed method was checked with recovery studies. The limit of detection and limit of quantitation were found to be 4.0 x 10(-7) and 9.0 x 10(-7)M, respectively. Rapidity, precision, and good selectivity were also found for the determination of pantoprazole in pharmaceutical dosage forms and human plasma. For comparative purposes high-performance liquid chromatography with a diode array and UV/VIS detection at 290.0 nm determination also was developed.     

Macromolecular interactions with cadmium and the effects of zinc,copper, lead,and mercury ions

Interactions of cadmium (Cd) ions with bovine serum albumin (BSA), bovine hepatic metallothionein (MT), calf thymus histone and deoxyribonucleic acid (DNA), and bovine hepatic chromatins were studied in the presence and absence of divalent zinc (Zn), copper (Cu), mercury (Hg), or lead (Pb) ions, using equilibrium dialysis at pH 7 and at 37°C. The BSA had 3.5 Cd-binding sites with an apparent affinity constant of 1×10⁵. The other metal ions inhibited the binding by reducing the affinity constant and the number of Cd-binding sites in BSA. There were 6 high affinity and 13 low affinity Cd-binding sites in the MT. Zinc ions had poor efficacy in reducing the binding of Cd to the MT. However, the Cu²⁺ and Hg²⁺ ions inhibited the Cd binding to a considerable extent, the former ions being more potent in this respect. Histone did not bind Cd. There were two kinds of Cd-binding sites in DNA: One mole of Cd per four moles DNA-phosphorus at low affinity sites, and one mole of Cd per 6.7 moles DNA-phosphorus at high affinity sites. Their apparent association constants were 8.3×10⁵ and 4.4×10⁶ M, respectively. The other metal ions had inhibitory effects on the binding of Cd to DNA. Histone reduced the Cd-DNA interactions to only a minor extent. The other metal ions reduced the binding of Cd to DNA-histone complex to a small extent. Cadmium binds to the euchromatin (Euch), heterochromatin (Het), and Euch-Het mixture almost equally. The other metal ions reduced the binding maximally in Euch-Het followed next in order by Het and Euch. Cupric ions were the most potent inhibitors of the interactions of Cd with the nuclear materials.     

Removal of chromium(VI) and cadmium(II) from aqueous solution by a bacterial biofilm supported on granular activated carbon

A biofilm of Arthrobacter viscosus, supported on granular activated carbon, removed between 100% and 50% of Cr(VI) and between 100% and 20% of Cd(II) from solutions with initial concentrations between 4–11 mg_metal l^–1 and a flow residence time of 1.2 min. For experiments of lower initial concentrations, a steady-state removal of 50% was reached after 71 bed volumes of Cr solution passed through the biosorbent bed and a steady-state removal of 30% was reached after 47 bed volumes of Cd solution passed through a similar bed. Final uptakes of 8.5 mg_Cr g_carbon^–1 and 4.2 mg_cd g_carbon^–1 were determined for initial concentrations of 10 mg_Cr l^–1 and 11 mg_Cd l^–1, respectively. The influence on the overall process of two different surface treatments of the support was evaluated and compared with the behavior of a support not treated.     

Kinetic and equilibrium studies of copper biosorption onto <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> base using direct determination of copper by a voltammetric method

This paper provided information on the use of linear sweep anodic stripping voltammetry for evaluating the process of copper biosorption onto Pseudomonas aeruginosa. This technique was suited to determine the concentration of free copper ion on site on the mercaptoethane sulfonate modified gold electrode surface without any pretreatment. It was in favor of the study of kinetic process as the fast changing kinetic data characteristic just after the beginning of biosorption could be accurately depicted. Based on the electrochemical results, the kinetics and equilibrium of biosorption were systematically examined. The pseudo-second-order kinetic model was used to correlate the kinetic experimental data and the kinetic parameters were evaluated. The Langmuir and Freundlich models were applied to describe the biosorption equilibrium. It was found that the Langmuir isotherm fitted the experimental data better than the Freundlich isotherm. Maximum adsorption capacity of copper ion onto Pseudomonas aeruginosa was 0.9355 μmol mg⁻¹ (about 59.4417 mg g⁻¹).     

Separation of monoclonal antibodies from cell-culture supernatants and ascites fluid using thiophilic agarose

A one-step purification procedure will yield monoclonal antibodies from cell-culture supernatants and ascites fluids. The chromatographic adsorbant is thiophilic argose, i.e., beaded agarose gel coupled with ligands of thiophilic nature, often with a sulfone group and a sulfur atom. The chromatographic procedure is simply adsorption, wash, elution. The procedure is simple, efficient, and inexpensive.     

The distribution of cadmium,copper, lead,zinc and calcium in the tissues of the earthworm Lumbricus rubellus sampled from one uncontaminated and four polluted soils

Summary The tissue distribution of Cu, Cd, Pb, Zn, and Ca in the earthworm Lumbricus rubellus living in non-polluted and heavy-metal polluted soils was investigated. Cd, Pb and Zn were primarily accumulated within the posterior alimentary canal. As the whole-worm Pb burden increased, the proportion of the metal accumulated within this tissue fraction increased. A similar pattern was found for Zn. By contrast, 70%–76% of the Cd burden was found in the posterior alimentary canal, irrespective of the whole-worm Cd content. The accumulation of Cd, Pb and Zn primarily in the posterior alimentary canal prevents dissemination of large concentrations of these metals into other earthworm tissues, and may thus represent a dextoxification strategy based on accumulative immobilisation. Cu was distributed fairly evenly in the tissue fractions investigated. There was no evidence of sequestration of this metal. The apparent lack of a detoxification strategy may contribute to the well-known susceptibility of earthworms to low environmental Cu concentrations. Indeed, earthworms from the site of highest soil Cu (Ecton) were markedly smaller than those from the other sites sampled. The highest Ca concentrations were found in the anterior alimentary canal, and were related to calciferous gland activity. A large proportion of Ca was also stored as a physiologically available pool in the posterior alimentary canal. Despite huge variations in soil Ca concentrations, the body wall Ca levels were fairly similar in L. rubellus from all the study sites. Thus, L. rubellus may become physiologically adapted to soils of exceptionally low Ca concentration. The observations are discussed in the context of the merits of analysing specific tissues, rather than whole organisms, for the purpose of monitoring metal bioaccumulation.     

Determination of cadmium,cobalt, copper,iron, manganese,and zinc in thyroid glands of patients with diagnosed nodular goitre using ion chromatography

The aim of this study was to estimate and compare the contents of selected metals in 65 pathological (diagnosed nodular goitre) and 50 healthy human thyroid tissues (taken during autopsies). Ion chromatography (IC) preceded by microwave mineralization was applied for the first time for determination of cadmium, cobalt, copper, iron, manganese, and zinc in human thyroid samples. The study proved that the concentrations of Cu²⁺, Mn²⁺, Fe³⁺, and Zn²⁺ were significantly higher in the control group (healthy thyroids) in comparison with the studied group (nodular goitre) (p < 0.05), whereas for Co²⁺ the difference between two means of concentration (healthy vs pathological thyroids) was not significant statistically at 0.05 significance level. Measurement accuracy was verified by measurements of NIST standard reference material (1566a Oyster Tissue). Very good precision (RSD below 5%) and recoveries (above 90%) were evaluated.     

Effects of copper and cadmium ions on the physicochemical properties of lipids of the marine bacterium <Emphasis Type="Italic">Pseudomonas putida</Emphasis> IB28 at different growth temperatures

The phospholipid and fatty acid composition and thermotropic behavior of total lipids were studied in the metal-accumulating marine strain Pseudomonas putida IB28 grown in the presence of Cu²⁺ and Cd²⁺ at 4 and 24°C. Despite the changes in acidic lipid content, unsaturated/saturated fatty acid ratio, and cyclopropane fatty acid level, the temperature range of calorimetric phase transitions of bacterial total lipids was slightly altered under these factors. The suppressive action of heavy metals on bacterial growth is attributable to the phase separation of lipids and, as a consequence, to a sharp increase in the ion permeability of the lipid bilayer. The increase in acidic phospholipid level under the influence of Cu²⁺ and Cd²⁺, especially at 24°C, is likely to be indicative of their complexation with heavy metal ions.     

Impact of encrusting carbonates on manganese,zinc and copper concentrations of two vascular hydrophytes from Texas

In alkaline calcareous waters, hydrophytes become encrusted with carbonate precipitates of a complex nature which alter bulk chemical analyses of the plants. The manganese, zinc and copper concentrations, and the ash content of two aquatic plants, Egeria densa and Potamogeton nodusus, differed considerably depending on the cleaning procedure used and, therefore, the amount of marl encrustation included in the analyses. Tapwater washed plants, retaining the marl, consistently had ash contents two to three times higher than acid-cleaned plants and exhibited higher trace metal concentrations, especially manganese.     

Studies on the effects of the antitumor agent camptothecin and derivatives on DNA. Camptothecin potentiated cleavage of DNA by bleomycin in vitro

Addition of sodium camptothecin (2a, Fig. 1) in comparable low concentrations to the glycopeptide antitumor antibiotic bleomycin (BLM) leads to enhanced rates of single-strand scission of PM2-covalently closed circular DNA, whereas sodium camptothecin alone has no effect. A similar enhancement of DNA scission by sodium camptothecin is produced with the 1 : 1 bleomycin-iron complex alone or in conjunction with NADPH as an additional reductant. The interpretation that camptothecin may substitute for the reducing requirement of the antibiotic is supported by its oxidation at 37°C by the 1 : 1 bleomycin iron complex, by iron salts or more efficiently by hydrogen peroxide to the known hemiacetal (3, Fig. 1).Electrochemical studies of 2a, its analogues and selected model compounds established that the α-pyridone ring D is most susceptible to a one-electron reduction at a reversible potential of ?0.95 ± 0.01 V. The reduced camptothecin is a transient species readily capable of donating an electron. This process may by compatible with a coupled reduction of the sequestered Fe(III) in the glycopeptide antibiotic necessary for the expression of antibiotic and antitumor properties. The results may provide a mechanistic rationale for the observed potentiation of the antitumor activity of bleomycin by camptothecin in vivo.