Sustainable sources of biomass for bioremediation of heavy metals in waste water derived from coal-fired power generation

Biosorption of heavy metals using dried algal biomass has been extensively described but rarely implemented. We contend this is because available algal biomass is a valuable product with a ready market. Therefore, we considered an alternative and practical approach to algal bioremediation in which algae were cultured directly in the waste water stream. We cultured three species of algae with and without nutrient addition in water that was contaminated with heavy metals from an Ash Dam associated with coal-fired power generation and tested metal uptake and bioremediation potential. All species achieved high concentrations of heavy metals (to 8% dry mass). Two key elements, V and As, reached concentrations in the biomass of 1543 mg.kg(-1) DW and 137 mg.kg(-1) DW. Growth rates were reduced by more than half in neat Ash Dam water than when nutrients were supplied in excess. Growth rate and bioconcentration were positively correlated for most elements, but some elements (e.g. Cd, Zn) were concentrated more when growth rates were lower, indicating the potential to tailor bioremediation depending on the pollutant. The cosmopolitan nature of the macroalgae studied, and their ability to grow and concentrate a suite of heavy metals from industrial wastes, highlights a clear benefit in the practical application of waste water bioremediation.     

Mammalian sensitivity to elemental gold (Au degrees)

There is increasing documentation of allergic contact dermatitis and other effects from gold jewelry, gold dental restorations, and gold implants. These effects were especially pronounced among females wearing body-piercing gold objects. One estimate of the prevalence of gold allergy worldwide is 13%, as judged by patch tests with monovalent organogold salts. Eczema of the head and neck was the most common response of individuals hypersensitive to gold, and sensitivity can last for at least several years. Ingestion of beverages containing flake gold can result in allergic-type reactions similar to those seen in gold-allergic individuals exposed to gold through dermal contact and other routes. Studies with small laboratory mammals and injected doses of colloidal gold showed increased body temperatures, accumulations in reticular cells, and dose enhancement in tumor therapy; gold implants were associated with tissue injuries. It is proposed that Au degrees toxicity to mammals is associated, in part, with formation of the more reactive Au+ and Au3+ species.     

Accumulation of elemental gold on the alga Chlorella vulgaris

The accumulation of Au(0) by lyophilized preparations of the alga Chlorella vulgaris has been investigated. Gold is bound to the algae upon suspending dried algal cells in solutions containing hydrogen tetrachloroaurate (III). Relative amounts of ionic and atomic algal-bound gold were determined by thiourea extraction. It was found that the amount of algal-bound atomic gold produced from ionic gold increased with time. The effect of algal-bound gold concentration on the rate and extent of gold reduction was observed. It is suggested that at least three different classes of sites are available for gold binding and reduction. The effect of Au(0) accumulation on the binding ability of gold-bound algae was also investigated, and an apparent enhancement of gold binding ability is reported.     

Integrated biological process for the treatment of a Chilean complex gold ore

Abstract: A process for gold recovery from a complex Chilean ore from Burladora (IV Region) which integrates concentration by flotation, bacterial leaching and cyanidation was studied at a laboratory scale. The chemical composition of the ore is 8.2% Fe, 0.78% Cu, 0.88% As and 3.5 g/t Au, with pyrite, hematite, covelite, arsenopyrite and chalcopyrite as the main metal-bearing minerals. The initial gold recovery by conventional cyanidation on a crushed ore sample was only 54%. The ore was ground and concentrated by flotation with a gold recovery of only 56%. The gold content of the concentrate is 17 g/I Au. Concentrate samples were leached in 1.5 l stirred reactors at 10% pulp density in 1000 ml of acid medium (pH 1.8). Some experiments were inoculated with harvested bacteria previously isolated from mining solutions. Dissolved metals, pH and bacteria concentration in the leaching solutions were periodically determined. In the presence of bacteria, oxidation of the ferrous ion produced by acid dissolution of the concentrate was observed, and after 4 days of leaching 100% of the dissolved iron was present as ferric ion. Gold recovery by cyanidation increased from 13% for the initial concentrate to 34% after 10 days of chemical acid leaching and 97% after 10 days of bacterial leaching. To increase the total gold recovery, the flotation tailings were submitted to cyanidation. A complete flowsheet of the process and a first economical evalualion are proposed. As a possible alternative process, heap bacterial leaching and further cyanidation of the ore are suggested.     

Antioxidants characterization in selected cyanobacteria

Antioxidants—molecules that have the ability to inhibit the oxidation of other molecules and have many medicinal and industrial applications—are commonly found in algae. Due to the harmful effects of common synthetic antioxidants, their replacement with natural antioxidants would be advantageous. The goal of this study was to examine the efficacy of antioxidants (including antioxidant content, antioxidant activity and antioxidant enzymes) among 11 species of freshwater blue-green algae. Antioxidant activities were evaluated by assaying radical scavenging activity, reducing power and chelating activity. The results showed that Spirulina platensis has the highest radical scavenging activity and reducing power (524 and 244 % more than the control, respectively) and Nostoc linkia has the highest chelating activity (195 %). Examination of some antioxidant contents such as chlorophyll a, carotenoids and phenolic content revealed that S. platensis has the highest contents [10.6 mg/g dry weight (DW), 2.4 mg/g DW and 9.7 mg gallic acid equivalent /g DW, respectively]. The positive correlation (P <0.01) between algal content and antioxidant activity may be attributed to the potent antioxidant activity of these contents. Variation in the activity of three antioxidant enzymes (superoxide dismutase, catalase and peroxidase) was also reported. This study showed that the Cyanobacteria are promising sources of antioxidants.     

A promising approach on biomass accumulation and withanolides production in cell suspension culture of Withania somnifera (L.) Dunal

Withanolide is one of the most extensively exploited steroidal lactones, which are biosynthesized in Withania somnifera. Its production from cell suspension culture was analyzed to defeat limitations coupled with its regular supply from the plant organs. In order to optimize the different factors for sustainable production of withanolides and biomass accumulations, different concentrations of auxins or cytokinins and their combinations, carbon sources, agitation speed, organic additives and seaweed extracts was studied in cell suspension culture. Maximum biomass accumulation (16.72 g fresh weight [FW] and 4.18 g dry weight [DW]) and withanolides production (withanolide A 7.21 mg/g DW, withanolide B 4.23 mg/g DW, withaferin A 3.88 mg/g DW and withanone 6.72 mg/g DW) were achieved in the treatment of Gracilaria edulis extract at 40 % level. Organic additive l-glutamine at 200 mg/l in combination with picloram (1 mg/l) and KN (0.5 mg/l) promoted growth characteristics (11.87 g FW and 2.96 g DW) and withanolides synthesis (withanolide A 5.04 mg/g DW, withanolide B 2.59 mg/g DW, withaferin A 2.36 mg/g DW and withanone 4.32 mg/g DW). Sucrose at 5 % level revolved out to be a superior carbon source yielded highest withanolides production (withanolide A 2.88 mg/g DW, withanolide B 1.48 mg/g DW, withaferin A 1.35 mg/g DW and withanone 2.47 mg/g DW), whereas biomass (7.28 g FW and 1.82 g DW) was gratefully increased at 2 % level of sucrose in cell suspension culture. This optimized protocol can be utilized for large scale cultivation of W. somnifera cells in industrial bioreactors for mass synthesis of major withanolides.     

Impact of metal pollution and Thlaspi caerulescens growth on soil microbial communities

Soil microorganisms drive critical functions in plant-soil systems. As such, various microbial properties have been proposed as indicators of soil functioning, making them potentially useful in evaluating the recovery of polluted soils via phytoremediation strategies. To evaluate microbial responses to metal phytoextraction using hyperaccumulators, a microcosm experiment was carried out to study the impacts of Zn and/or Cd pollution and Thlaspi caerulescens growth on key soil microbial properties: basal respiration; substrate-induced respiration (SIR); bacterial community structure as assessed by PCR-denaturing gradient gel electrophoresis (DGGE); community sizes of total bacteria, ammonia-oxidizing bacteria, and chitin-degrading bacteria as assessed by quantitative PCR (Q-PCR); and functional gene distributions as determined by functional gene arrays (GeoChip). T. caerulescens proved to be suitable for Zn and Cd phytoextraction: shoots accumulated up to 8,211 and 1,763 mg kg(-1) (dry weight [DW]) of Zn and Cd, respectively. In general, Zn pollution led to decreased levels of basal respiration and ammonia-oxidizing bacteria, while T. caerulescens growth increased the values of substrate-induced respiration (SIR) and total bacteria. In soils polluted with 1,000 mg Zn kg(-1) and 250 mg Cd kg(-1) (DW), soil bacterial community profiles and the distribution of microbial functional genes were most affected by the presence of metals. Metal-polluted and planted soils had the highest percentage of unique genes detected via the GeoChip (35%). It was possible to track microbial responses to planting with T. caerulescens and to gain insight into the effects of metal pollution on soilborne microbial communities.     

Screen of Chinese Weed Species for Cadmium Tolerance and Accumulation Characteristics

The cadmium (Cd) tolerance and metal-accumulation characteristics of 29 species (18 families) of weed were studied by using outdoor pot-culture experiments. The results of this screening showed that Bidens pilosa and Kalimeris integrifolia (both Asteraceae) expressed some properties that are characteristic of Cd hyperaccumulators. In 10 mg/kg Cd-spiked soil, they accumulated a good deal of Cd in shoots (28 and 25 mg/kg DW, respectively) with high Cd enrichment factors (EFs; concentration in plant/soil). Cd accumulations in shoots were greater than those in roots (translocation factor (TF) >1, concentration in shoot/root) and the shoot biomasses did not decreased significantly compared to the unspiked control. The other weed species showed little accumulation of Cd, Pb, Cu, or Zn. In a concentration-gradient experiment, the Cd accumulation potentials of B. pilosa and K. integrifolia were examined further. Cd concentrations in leaves of B. pilosa growing in soils spiked with 25, 50, and 100 mg/kg Cd were up to 145, 160, and 192 mg/kg, respectively, and the Cd content in stems in the 100 mg/kg Cd-spiked soil was 115 mg/kg, all greater than the 100 mg/kg notional criterion for Cd hyperaccumulation. The Cd EFs and TFs were all greater than 1. The shoot biomasses did not decrease significantly compared to the controls. B. pilosa was thus shown to have some characteristics of a true Cd hyperaccumulator plant.     

Uptake and recovery of gold ions from electroplating wastes using eggshell membrane.

The animal byproduct, hen eggshell membrane (ESM), was evaluated for its ability to sorb gold ions (dicyanoaurate(I) and tetrachloroaurate(III)) from solutions and electroplating wastewater. The gold uptake was dependent on pH, temperature and co-ions present in the solutions, with pH 3.0 being the optimum value. The equilibrium data followed the Langmuir isotherm model with maximum capacities of 147 mg Au(I)/g dry weight and 618 mg Au(III)/g, respectively. Desorption of sorbed gold(I) with 0.1 mol/l NaOH resulted in no changes of the biosorbent gold uptake capacity through five consecutive sorption/desorption cycles. In column experiments, selective recovery of gold from electroplating wastewater containing various metal ions was noted. The affinity of metal sorption was in the order Au > Ag > Co > Cu > Pb > Ni > Zn.     

云南两种食用地衣营养成分研究

测定云南两种食用地衣的主要营养成分 ,并与常见蔬菜及食用菌进行比较。测定结果 ,东方肺衣粗蛋白质含量为 11 0 2 g/ 10 0 g .DW ,粗脂肪 5 5 6 g/ 10 0g .DW ,总糖、可溶性糖、灰分含量分别为 0 6 2g/ 10 0 g、0 37g/ 10 0g、2 6 4g/ 10 0 g .DW ;裂髓树花 (新拟 )的粗蛋白质含量为 3 43g/ 10 0g .DW ,粗脂肪3 12 g/ 10 0g .DW ,总糖、可溶性糖、灰分含量分别为 0 79g/ 10 0 g、0 35g/ 10 0 g、2 99g/ 10 0 g .DW ;两种地衣均含有 17种氨基酸 (色氨酸未测 ) ,多种矿物元素 ,具有一定营养价值 ;且两种地衣营养成分的含量存在差异     

Reactions of gold(III) complexes with serum albumin.

The reactions of a few representative gold(III) complexes -[Au(ethylenediamine)2]Cl3, [Au(diethylentriamine)Cl]Cl2, [Au(1,4,8,11-tetraazacyclotetradecane)](ClO4)2Cl, [Au(2,2',2'-terpyridine)Cl]Cl2, [Au(2,2'-bipyridine)(OH)2][PF6] and the organometallic compound [Au(6-(1,1-dimethylbenzyl)-2,2'-bipyridine-H)(OH)][PF6]- with BSA were investigated by the joint use of various spectroscopic methods and separation techniques. Weak metal-protein interactions were revealed for the [Au(ethylenediamine)2]3+ and [Au(1,4,8,11-tetraazacyclotetradecane)]3+ species, whereas progressive reduction of the gold(III) centre was observed in the cases of [Au(2,2'-bipyridine)(OH)2]+ and [Au(2,2',2'-terpyridine)Cl]2+. In contrast, tight metal-protein adducts are formed when BSA is reacted with either [Au(diethylentriamine)Cl]2+ and [Au(6-(1,1-dimethylbenzyl)-2,2'-bipyridine-H)(OH)]+. Notably, binding of the latter complex to serum albumin results in the appearance of characteristic CD bands in the visible spectrum. It is suggested that adduct formation for both of these gold(III) complexes occurs through coordination at the level of surface histidines. Stability of these gold(III) complexes/serum albumin adducts was tested under physiologically relevant conditions and found to be appreciable. Metal binding to the protein is tight; complete detachment of the metal from the protein has been achieved only after the addition of excess potassium cyanide. The implications of the present results for the pharmacological activity of these novel cytotoxic agents are discussed.     

FATTY ACID CONTENT AND CHEMICAL COMPOSITION OF FRESHWATER MICROALGAE1

Fatty acid (FA), total lipid, protein, amino acid, carbon, nitrogen, and phosphorus content was analyzed in 24 samples of freshwater microalgae. The samples originated from batch, continuous, or mass cultures in various growth phases and from net samples from lakewater. FA were analyzed quantitatively by using an internal standard in a GLC system and expressed as mg·g^?1 dry weight (DW). The FA of one group of blue-greens (e.g. Oscillatoria and Microcystis) were similar to those of the greens with higher amounts of 18C acids of the ω3 type compared to the ω6 type, whereas the other group (e.g. Anabaena and Spirulina) contained mostly ω6 acids. The flagellates, a taxonomically diverse group, were characterized by high amounts of long-chained (20–22 C) polyunsaturated FA (PUFA), particularly of the ω3 type. The ω3/ω6 ratio appears to be highest in algae in the exponential growth phase. The increased lipid content in stressed algae was mostly due to increased saturated fatty acids and ω6 acids, whereas the valuable ω3 acids were unchanged or even decreased. Amino acid composition (% of total amino acids) did not vary much betaken species, but when analyzed quantitatively (mg-g^?1 DW), varied considerably between species and within species in different growth phases. The nitrogen and phosphorus contents were variable in all three algal groups. The relationship between PUFA and phosphorus content differed among the algal groups. The data suggest that PUFA in the phospholipids consist mostly ω3 acids.     

Synthesis of metallic nanoparticles using plant extracts

Biomolecules present in plant extracts can be used to reduce metal ions to nanoparticles in a single-step green synthesis process. This biogenic reduction of metal ion to base metal is quite rapid, readily conducted at room temperature and pressure, and easily scaled up. Synthesis mediated by plant extracts is environmentally benign. The reducing agents involved include the various water soluble plant metabolites (e.g. alkaloids, phenolic compounds, terpenoids) and co-enzymes. Silver (Ag) and gold (Au) nanoparticles have been the particular focus of plant-based syntheses. Extracts of a diverse range of plant species have been successfully used in making nanoparticles. In addition to plant extracts, live plants can be used for the synthesis. Here we review the methods of making nanoparticles using plant extracts. Methods of particle characterization are reviewed and potential applications of the particles in medicine are discussed.     

Chestnut pellicle for the recovery of gold

Recovery of Au(III) from hydrochloric acid medium by using crosslinked chestnut pellicle (CCP) gel was studied. Strong selectivity was observed for Au(III) showing negligible affinity for other precious metals and some base metal ions tested. The adsorption isotherm study exhibited the maximum loading capacity of the gel as high as 10.6 mol or about 2.1 kg gold per kg dry weight of gel. The reduction of Au(III) ion to elemental form during adsorption process is expected to be the reason of high selectivity and high capacity for Au(III). Kinetic studies at various temperatures confirm an endothermic adsorption process following the pseudo-first order rate law.     

建立金线莲原球茎悬浮体系生产次生代谢产物

研究植物激素浓度和培养周期对金线莲原球茎悬浮培养生长及其代谢产物积累的影响,以增加金线莲悬浮培养的生长量,提高次生代谢产物的生产。结果表明,MS培养基添加S-3307 1.0mg/L,6-BA0.5mg/L和3%的蔗糖适合总生物量的生长(214.45g/L,FW和18.23g/L DW)。而MS培养基添加S-3307 1.0mg/L,6-BA 3.0mg/L和5%的蔗糖,总黄酮,总酚和多糖的干重(5.43mg/g,2.87mg/g和243.23mg/g)达到最大化。研究原球茎悬浮培养过程,发现经过7个星期培养就能获得最大的生物质总量(225.98 g/L的FW和18.53 g/L的DW)、总黄酮干重(5.09mg/g)和总酚干重(2.04mg/g),而多糖生产达到其峰值(229.36mg/g干重)是在培养后5个星期。     

Synthesis of Silver and Gold Nanoparticles Using Cashew Nut Shell Liquid and Its Antibacterial Activity Against Fish Pathogens

This study reveals a green process for the production of multi-morphological silver (Ag NPs) and gold (Au NPs) nanoparticles, synthesized using an agro-industrial residue cashew nut shell liquid. Aqueous solutions of Ag⁺ ions for silver and chloroaurate ions for gold were treated with cashew nut shell extract for the formation of Ag and Au NPs. The nano metallic dispersions were characterized by measuring the surface plasmon absorbance at 440 and 546 nm for Ag and Au NPs. Transmission electron microscopy showed the formation of nanoparticles in the range of 5–20 nm for silver and gold with assorted morphologies such as round, triangular, spherical and irregular. Scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction analyses of the freeze-dried powder confirmed the formation of metallic Ag and Au NPs in crystalline form. Further analysis by Fourier transform infrared spectroscopy provided evidence for the presence of various biomolecules, which might be responsible for the reduction of silver and gold ions. The obtained Ag and Au NPs had significant antibacterial activity, minimum inhibitory concentration and minimum bactericidal concentration on bacteria associated with fish diseases.     

Is osmotic adjustment required for water stress resistance in the Mediterranean shrub Atriplex halimus L?

The effect of water stress was investigated in plants from two populations of Atriplex halimus L: Tensift issued from a salt-affected coastal area and Kairouan, originating from an inland dried site. Water deficit was applied by withholding water for 22 days. Shoot dry weight (shoot DW), leaf relative water content (RWC), turgid weight to dry weight ratio (TW/DW), osmotic potential (psis), osmotic adjustment (OA), proline, glycinebetaine, and sugar content were determined 1, 8, 15 and 22 days after withholding watering. Water stress induced a decrease in shoot DW, RWC, psis, and TW/DW, but an increase in glycinebetaine and sugar leaf contents. The decrease of psis and TW/DW was more marked in Kairouan than in Tensift. At the end of the stress period, Kairouan showed a greater OA compared with Tensift. However, the contribution of net solute accumulation (OAacc) was similar in both populations in response to stress. Water stress resistance could thus not be associated with higher OA, although the ability of plants to regulate these metabolic and physiological functions could play an important role under harmful conditions. The possible roles of osmolyte accumulations are discussed in relation to the specific physiological strategy of water-stress-resistance in this species.     

The effect of a duckweed cover on sulphide volatilisation from waste stabilisation ponds

The effects of a duckweed (DW) cover on the surface of waste stabilisation ponds on sulphide emissions were studied in a laboratory scale set-up of an anaerobic pond-reactor, followed by two algae (A) pond-reactors and two duckweed (Lemna gibba) pond-reactors. The concentrations of various S-components were measured at different depth in the reactors, while sulphide emissions were measured at the surface. Presence of a duckweed cover on the anaerobic pond-reactor resulted in a reduction of 99% in sulphide emission. In algae pond-reactors, sulphide emissions were negligible through chemical and biological conversion of sulphide. In the duckweed pond-reactors, colourless sulphur bacteria (Beggiatoa sp.) were observed on the duckweed roots. Batch tests showed that both micro-biological and possibly chemical oxidation occurred in a typical duckweed pond environment. The duckweed cover reduced H₂S volatilisation via two mechanisms, by forming a physical barrier and by providing attachment area for sulphide oxidising bacteria.     

Selenium accumulation in plants--phytotechnological applications and ecological implications

Selenium (Se) is an essential trace element for many organisms including humans, yet toxic at higher levels. Both Se deficiency and toxicity are problems worldwide. Since plants readily accumulate and volatilize Se, they may be used both as a source of dietary Se and for removing excess Se from the environment. Plant species differ in their capacity to metabolize and accumulate Se, from non-Se accumulators (< 100 mg Se/kg DW), to Se-accumulators (100-1000 mg Se/kg DW) to Se hyperaccumulators (> 1,000 mg Se/kg DW). Here we review plant mechanisms of Se metabolism in these various plant types. We also summarize results from genetic engineering that have led to enhanced plant Se accumulation, volatilization, and/or tolerance, including field studies. Before using Se-accumulating plants at a large scale we need to evaluate the ecological implications. Research so far indicates that plant Se accumulation significantly affects the plant's ecological interactions below and above ground. Selenium canprotect plants from fungal pathogens and from a variety of invertebrate and vertebrate herbivores, due to both deterrence and toxicity. However, specialist (Se-tolerant herbivores), detritivores and endophytes appear to utilize Se hyperaccumulator plants as a resource. These findings are relevant for managing phytoremediation of Se and similar elements.     

传统发酵豆酱发酵过程中养分动态及细菌多样性

以山东传统发酵豆酱作为研究对象, 测定了发酵不同阶段的总酸、可溶性糖、有机碳、粗蛋白、氨基酸态氮、主要挥发性产物等指标, 对样品中细菌进行PCR-DGGE分析, 探讨了传统发酵豆酱中养分动态及细菌多样性。结果表明发酵过程中总酸含量先上升后下降而后又上升, 最后成品酱中为6.26%; 有机碳和可溶性糖含量都逐渐减少; 粗蛋白相对含量先略有平稳上升后下降; 氨基酸态氮含量一直在增加, 成品酱中为101.2 g/kg; 乳酸和甘油含量随发酵进程而增加, 成品酱中分别为5.65 g/kg和14.72 g/kg。DGGE分析表明发酵15 d时细菌种类最多, 随后一部分逐渐消失, 种类趋于稳定, 最后成品酱中出现有几种明显的优势种, 主要包括：未培养细菌(Uncultured bacterium)、乳酸乳球菌(Lactococcus lactis)、地衣芽孢杆菌(Bacillus licheniformis)的近缘种。