Cadmium and zinc biosorption byChlorella homosphaera

Summary Cadmium and zinc biosorption byChlorella homosphaera cells were tested under laboratory conditions, in a range of concentrations from 0.5 to 14.0 mg/l. The results indicated two distinct phases for cadmium biosorption: a rapid phase probably associated with metal adsorption around the cell wall and a slower phase associated with the metal transport into the interior of the cells. For zinc biosorption these phases were not well defined probably due to the metabolic use of this metal by the cells.     

The effects of copper and zinc on <Emphasis Type="Italic">Spirulina platensis</Emphasis> growth and heavy metal accumulation in its cells

The effects of copper and zinc on Spirulina platensis (Nordst.) Geitl. growth and the capability of this cyanobacterium for accumulation of these heavy metals (HMs) were studied. S. platensis tolerance to HMs was shown to depend on the culture growth phase. When copper was added during the lag phase, its lethal concentration was 5 mg/l, whereas 4 mg/l were lethal during the linear growth phase. Zinc concentration of 8.8 mg/l was lethal during the linear but not lag phase of growth. HM-treated S. platensis cells were capable for accumulation of tenfold more copper and zinc than control cells. Independently of Cu²⁺ content in the medium and of the growth phase, cell cultures accumulated the highest amount of this metal as soon as after 1 h, which may be partially determined by its primary sorption by cell-wall polysaccharides. A subsequent substantial decrease in the intracellular copper content occurred due to it secretion, which was evident from the increased metal concentration in the culturing medium. When zinc was added during the linear growth phase, similar pattern of its accumulation was observed: the highest content after 1 h and its subsequent decrease to the initial level. When the initial density of the culture was low and the cells had much time to adapt to HM, zinc accumulated during the entire linear growth phase, and thereafter the metal was secreted to the medium. The mechanisms of S. platensis tolerance to HM related to both their sorption by the cell walls and secretion of metal excess into the culturing medium and its conversion into the form inaccessible for the cells are discussed.Translated from Fiziologiya Rastenii, Vol. 52, No. 2, 2005, pp. 259–265.Original Russian Text Copyright © 2005 by Nalimova, Popova, Tsoglin, Pronina.This revised version was published online in April 2005 with a corrected cover date.     

Development of a process for biodetoxification of metal cyanides from waste waters

A bacterial consortium capable of utilising metal cyanides as a source of nitrogen was used to develop a microbiological process for the detoxification of metal cyanides (viz. copper cyanide and zinc cyanide) from electroplating waste water. Optimal conditions biodegradation of both the metal-cyanide compounds were pH 7.5, temperature 35°C, inoculum size 10⁹ cells per ml and glucose or sugarcane molasses requirement of 5 mM or 0.6 ml/l, respectively. Metal precipitates obtained during metal-cyanide biodegradation were identified as metal-hydroxides. When the treatment was carried out in a 27 l rotating biological contactor (RBC) in continuous mode, the system could achieve >99.9% removal of 0.5 mM metal cyanide (ca. 52 mg/l cyanide and 30–40 mg/l copper/zinc) in 15 h with sugarcane molasses as carbon source. The RBC treated effluent was found to be safe for discharge in the environment as confirmed by chemical analysis and fish bioassay studies.     

Chromium and cadmium removal from wastewater using duckweed - Lemna gibba L. and ultrastructural deformation due to metal toxicity

Phytoremediation potential of Lemna gibba was evaluated for chromium (Cr) and cadmium (Cd) under laboratory conditions for variable metal load of 1?mg/l, 3?mg/l, 5mgl, 7?mg/l and 9?mg/l, respectively, for 7 and 15?days of treatment period. Effects of both metals on structural attributes of L. gibba were also analyzed by Scanning Electron Microscopic (SEM) study. The metal removal percentage by L. gibba for Cr metal was found in the range of 37.3% to 98.6% and for cadmium it was found within the range of 81.6% to 94.6%. Bio concentration factor (BCF) of L .gibba was observed within the range of 37 to 295 for Cr metal and for Cd metal it ranged from 237 to 1144, which shows that the plant is a hyper accumulator for Cd metal and moderate accumulator for Cr metal. Statistical analysis (Two-way ANOVA) was performed on experimental results to confirm the individual effect of metal concentration and treatment period as well as cumulative effect of both factors together on percentage metal removal and on BCF. Research studies indicated that with the progress of treatment period metal removal percentage increases but increasing metal load during experiment negatively co-relates the metal removal percentage and BCF.     

Performance of a membrane bioreactor used for the treatment of wastewater contaminated with heavy metals

In this work the performance of a Membrane bioreactor (MBR) was assessed for the removal of 3-15 mg/l of copper, lead, nickel and zinc from wastewater. The average removal efficiencies accomplished by the MBR system were 80% for Cu(II), 98% for Pb(II), 50% for Ni(II) and 77% for Zn(II). The addition of 5 g/l vermiculite into the biological reactor enhanced metal removal to 88% for copper, 85% for zinc and 60% for nickel due to adsorption of metal ions on the mineral, while it reduced biomass inhibition and increased biomass growth. The metal ions remaining in soluble form penetrated into the permeate, while those attached to sludge flocs were effectively retained by the ultrafiltration membranes. The average heterotrophic biomass inhibition was 50%, while it reduced to 29% when lower metal concentrations were fed into the reactor in the presence of vermiculite. The respective autotrophic biomass inhibition was 70% and 36%. The presence of heavy metals and vermiculite in the mixed liquor adversely impacted on membrane fouling.     

Germination et culture aseptique de Thlaspi sylvestre Jord. subsp. calaminare (Lej.) Maly

We have studied the action of different zinc concentrations (10, 50 and 100 mg/l) on the germination of Thlaspi seeds and on the seedlings obtained from them when grown on water containing the same zinc concentrations. It appears that the 10 mg/l zinc concentration enhances slightly the percentage germination and that the 50 mg/l concentration is the optimum one for the growth of the seedlings. Therefore it seems that the normal growth of a plant growing on a “calamine soil” demands a given quantity of zinc, the optimum being in the neighbourhood of 50 mg/l.     

Pyrene degradation and copper and zinc uptake by Fusarium solani and Hypocrea lixii isolated from petrol station soil

Aims: This study aimed to isolate and identify potential polycyclic aromatic hydrocarbon (PAH)‐degrading and/or metal‐tolerant fungi from PAH‐contaminated and metal‐contaminated soils. Methods and Results: Pyrene‐degrading fungi were isolated from contaminated soil and tested for metal (Cu, Zn and Pb) compound solubilization and metal accumulation. Three strains of Fusarium solani and one of Hypocrea lixii were able to degrade more than 60% of initial supplied pyrene (100 mg l^?1) after 2 weeks. The isolates were grown on toxic metal (Cu, Pb and Zn)‐containing media: all isolates accumulated Cu in their mycelia to values ranging from c. 5·9 to 10·4 mmol per kg dry weight biomass. The isolates were also able to accumulate Zn (c. 3·7–7·2 mmol per kg dry weight biomass) from zinc phosphate‐amended media. None of the isolates accumulated Pb. Conclusions: These fungal isolates appear to show promise for use in bioremediation of pyrene or related xenobiotics and removal of copper and zinc from wastes contaminated singly or in combination with these substances. Significance and Impact of the Study: Microbial responses to mixed organic and inorganic pollution are seldom considered: this research highlights the abilities of certain fungal strains to interact with both xenobiotics and toxic metals and is relevant to other studies on natural attenuation and bioremediation of polluted sites.     

Effects of abiotic factors (temperature,pH, heavy metals) on activities of glycosidases in invertebrate animals

Differences in amylolytical activity have been established in the whole body of some invertebrate animals (larvae of chironomids Chironomus plumosus, pond snail Limnaea stagnalis, orb snail Planorbis corneus, faucet snail Bithynia tentaculata, and zebra mussel Dreissena polymorpha-potential objects of nutrition of fish benthophages under separate and combined actions of temperature (0, 10 or 20°C), pH (5.0, 7.4 or 8.3), and ions of heavy metals (copper, zinc at a concentration of 10 mg/l) in vitro. The most pronounced inhibitory effect on the amylolytical activity in tissues of the studied animals was produced by a combination of the low temperature, acidic pH values, and the presence of the heavy metal ions. Enzymes of chironomids were more resistant to action of the studied agents as compared with molluscs.     

EFFECTS OF BENLATE ON FERN GAMETOPHYTE DEVELOPMENT

The widely used fungicide, benlate, was tested for its effect(s) on gametophyte development in the fern Ceratopteris thalictroides (L.) Brongn. The active ingredient of benlate, benomyl, represents 50% of the fungicide by weight. Seven concentrations of benomyl were tested on C. thalictroides gametophytes: 0, 0.001, 0.01, 0.1, 1.0, 10.0 and 100 mg/l. Five developmental stages were observed for possible effects of benomyl. These were 1) germination, and the initiation of 2) antheridia, 3) notch meristems, 4) archegonia, and 5) sporophytes. Overall inhibition was greatest at 100 mg/l benomyl. At 10 mg/l and 100 mg/l, sporophyte initiation was completely blocked. This was probably the consequence of two characteristics found only on gametophytes growing on medium containing 10 mg/l and 100 mg/l benomyl. These characteristics were lack of sperm motility and production of callus growths in the areas proximal to the notch meristems, just proximal to the younger archegonia. Besides blocking the completion of sexual reproduction, the highest concentrations tested also produced smaller (cell number) and chlorotic gametophytes (especially at 100 mg/l). The bigametophyte population (made up of hermaphroditic and male gametophytes) was changed from 51% hermaphrodites (at 0 mg/l benomyl) to 26% hermaphrodites at 100 mg/l. This would, since only hermaphrodites possess archegonia, also decrease the potential for the production of sporophytes.     

Effect of Some Dithiocarbamates on Respiration Activity of a Myxomycete

The presenl article aims at giving some information concerning the mode of action of three dithiocarbamates: ferric dimethyldithiocarbamate (Ferbam), zinc dimethyl-dithiocarbomate (Ziram) and tetramethylthiuram disulfide (Thiram). These inhibitors were tested on the respiratory activity of the Myxomycete: Physarum polycephalum. Its development is strongly inhibited at 285 mg/l. With such concentration, respiration measurements confirmed total inhibition of O₂ uptake. After isolation of the mitochondria, the tests showed that there may be an inhibition of the succinic oxidase activity of this particulate fraction, at 28.5 mg/l of Thiram. Heavy concentration of reduced glutathione (1.4 %) reversed partially this Inhibition. This seems to prove that succinic dehydrogenase is a typical SH-type enzyme.     

Selection of optimum biological sludge for zinc removal from wastewater by a biosorption process

Summary Biosorption of zinc by sludge micro-organisms obtained from different steps of a conventional SWT plant has been studied. The best types of activated sludge for the process were found to be thickened, anaerobic and dewatered sludge giving up to 90–98% of metal elimination when working at initial zinc concentration lower than 50 mg/l. A relationship between pH and conditional stability constant has been found.     

Metal-induced inhibition of anaerobic metabolism of volatile fatty acids and hydrogen

The effects of copper (Cu), chromium (Cr), cadmium (Cd), lead (Pb) and zinc (Zn) on the biotransformation of organic acids (acetate, propionate and butyrate) and H₂ were assessed in serum-bottle microcosms. Experiments were performed over a range of metal concentrations (20–200 mg/1) using biomass from an anaerobic bioreactor fed continuously with ethanol distillery waste as inoculum. In general, the added metals inhibited the biotransformation of organic acids with increasing metal concentration. However, the extent of inhibition varied for the different biotransformations and for the different metals tested. For example, the concentration of CuCl₂ effecting a 50% reduction in the rate constant for biotransformation of acetate, propionate and butyrate was 60, 75 and 30 mg/1, respectively. Cu and Cr (VI) were the most inhibitory metals in organic acid transformation, whereas Pb was the least toxic. The rate of biotransformation of acetate was reduced by half at Cu and Cr concentrations of 60 and 40 gm/1 respectively, whereas Cd, Pb, and Zn concentrations of 160 to 200 mg/l had little effect. The activities of hydrogenotrophic methanogens were much less affected by the same metals and metal concentrations.     

Micropropagation of the Thai orchid <Emphasis Type="Italic">Grammatophyllum speciosum</Emphasis> blume

Protocorm-like bodies (PLBs) were induced from shoot tips of Grammatophyllum speciosum, a Thai orchid. The highest frequency of PLBs (93%) were observed on explants incubated on 1/2-Murashige and Skoog (MS) liquid medium containing 2% (w/v) sucrose without any plant growth regulators (PGRs). Tests with different carbon sources compared to sucrose revealed that maltose promoted the highest relative growth of G. speciosum PLBs (7-fold increase), while trehalose and sucrose yielded 5-fold and 4-fold increases, respectively. In 1/2 MS liquid medium, addition of 15 mg/l of chitosan promoted a 7-fold increase in PLB growth while 25 mg/l promoted a 4-fold increase. However, the relative growth rate in solid culture was significantly lower than that in liquid culture. In addition, chitosan supplementation in solid medium promoted shoot formation but not rooting. Plantlet regeneration was induced using a combination of NAA and BA supplementation in 1/2 MS solid medium with optimum induction shoot and root formation at 2.0 mg/l NAA and 1.0 mg/l BA. Using this protocol, approximately 8 months was required to obtain a hundred plantlets from one shoot tip. The plantlets showed no changes in ploidy when tested by flow cytometry.     

A two-stage pretreatment of seedlings improves adventitious shoot regeneration in sugar beet (<Emphasis Type="Italic">Beta vulgaris</Emphasis> L.)

The effects of a two-stage pretreatment of seedlings on the subsequent shoot regeneration capacity were investigated. Pretreated seedlings were obtained by germinating seeds on three different germination media and then further culturing on six different growth media. Lamina and petiole explants of two sugar beet (Beta vulgaris L.) breeding lines were then excised from the pretreated seedlings and cultured on five different shoot regeneration media. In both breeding lines, petiole explants produced significantly more shoots than lamina explants with higher frequencies of organogenic capacities; petiole explants of the lines M1195 and ELK345 produced a mean of 2.1 and 2.7 shoots per explant while their lamina explants produced 1.5 and 2.2 shoots per explant, respectively. A genotypic variation was evident as the line ELK345 was more productive for shoot development from both types of explants. In overall comparisons of different germination, growth and regeneration media, germination medium was most effective when supplemented with 0.5 mg/l 6-benzyladenine (BA) while both growth and regeneration media were most productive when contained a combination of 0.25 mg/l BA and 0.10 mg/l indole-3-butyric acid (IBA). Of all the treatments tested, the highest mean number of shoots per explant (8.3 shoots) and frequency of organogenic explants (75.6%) were obtained on regeneration medium supplemented with 0.25 mg/l BA and 0.10 mg/l IBA when petiole explants of the line ELK345 were excised from the seedlings that had been germinated on medium containing 0.5 mg/l BA followed by further growth on medium containing 0.25 mg/l BA and 0.10 mg/l IBA.     

Lead and nickel removal using Microspora and Lemna minor

Aquatic plants can remove heavy metal contamination from the surrounding water. This study examined the ability of Microspora (a macro-alga) and Lemna minor (an aquatic plant) to remove soluble lead and nickel under various laboratory conditions. Microspora was tested in a batch and semi-batch process for lead removal. L. minor was tested in a batch process with lead and nickel to examine the potential competition between metals for adsorption. The Microspora was exposed to 39.4 mg/l of lead over 10 days. Results show up to 97% of the lead was removed in the batch process and 95% in the semi-batch process. Initial concentrations below 50 mg/l (a dose that kills the algae) had no effect on the final concentration. The L. minor was exposed to lead and nickel using a full 3(2) factorial experimental design (nine experiments, plus replications). Initial lead concentrations were 0.0, 5.0, and 10.0 mg/l, and nickel concentrations were 0.0, 2.5, and 5.0 mg/l in the experiment. Overall, L. minor removed 76% of the lead, and 82% of the nickel. No synergistic/antagonistic effect was noted for the multiple metal experiments, in terms of metal removal.     

Quantified elemental changes inAspidisca cicada andVorticella convallaria after exposure to aluminium, copper, and zinc

Summary Data on metal-induced elemental changes in eukaryotic unicellular organisms, such as protozoa, are rare. This study focused on two species of ciliate protozoa,Aspidisca cicada andVorticella convallaria, both common and abundant in activated sludge. Elemental changes in cells exposed to aluminium, copper, and zinc were determined by scanning electron microscopy-electron probe X-ray microanalysis. X-ray emission spectra obtained from cells 2 h after resuspension in Chalkley's medium (control) showed clear, characteristic peaks for magnesium, silicon, phosphorus, sulphur, potassium, and copper. These elements were also routinely detected in all cells resuspended in metal solution. Spectra obtained from cells treated with aluminium or zinc showed additional distinct peaks for aluminium and zinc. In copper-treated cells enhanced copper peaks were seen. Mean aluminium levels were low inA. cicada control cells (0.14mg/g of dry weight) but higher in cells treated with 0.50 ppm (0.69 mg/g of dry weight) and 2.00 ppm aluminium (2.07 mg/g of dry weight).A. cicada was ten times more sensitive to copper than to the other metals, and thanV. convallaria. There was a significantly higher concentration of copper inA. cicada cells treated with 0.20 ppm copper (2.94 mg/g of dry weight) than in control cells (2.16 mg/g of dry weight). InA. cicada cells treated with 0.50 and 2.00 ppm zinc significantly higher levels of zinc (2.41 and 2.07 mg/g of dry weight, respectively) were observed than in the control (0.41 mg/g of dry weight). After treatment with 0.50 ppm and 2.00 ppm aluminium, aluminium was significantly higher in the treatedV. convallaria cells (1.58 and 0.67 mg/g of dry weight, respectively) than in control cells (0.14 mg/g of dry weight). After treatment with 2.00 ppm copper there was significantly more copper in treatedV. convallaria cells (3.63 mg/g of dry weight) than in controls (2.08 mg/g of dry weight). InV. convallaria cells treated with 0.50 ppm and 2.00 ppm zinc there was an increase in the amount of zinc in cells (1.30 and 2.68 mg/g of dry weight, respectively) compared with control cells (0.34 mg/g of dry weight). Data on other changes in intracellular elements in both species, after 2 h exposure to aluminium, copper, and zinc medium are given. In both species, there was uptake and/or accumulation of aluminium, copper, and zinc when the external concentration of the metal was increased. Intracellular elemental levels were altered by sublethal and toxic external concentrations of the metals studied.A. cicada was ten times more sensitive to copper than to aluminium or zinc, and thanV. convallaria to the metals studied.     

Demonstration of reduced levels of zinc in rat brain after treatment with d-amphetamine,but not after treatment with reserpine

Summary Histochemical and atomic absorption spectrophotometric methods were used to study the effects of reserpine and d-amphetamine on the neuronal trace metal distribution in various regions of the central nervous system (hippocampus, parietal cortex, cerebellum). Six hours after single d-amphetamine treatment (15 mg/kg i.p.), the neuronal zinc level was significantly decreased in the hippocampus and in the parietal cortex. The intensity of sulphide silver staining was similarly greatly decreased in all layers of the hippocampus and the parietal cortex. Such a change was not observed when d-amphetamine was administered in a lower dose (5 or 10 mg/kg i.p.).Twenty hours after single reserpine treatment (10 mg/kg i.p.), there were no changes in the tissue levels and distribution of zinc, copper, iron and manganese. In animals treated with reserpine on five consecutive days, in a dose of 10 mg/kg/day i.p., the trace metal distribution twenty hours following the final treatment was essentially the same as in the control.The results strongly suggest that zinc does not play a direct role in vivo in the storage and mobilization processes of the catecholamines. A high dose of d-amphetamine, however, has a non-specific, toxic effect that is not interrelated with the catecholaminergic neuronal function; this effect is manifested in a diminished intensity of sulphide silver staining and in a reduction of the tissue zinc level.     

Comparison of the Adsorption Capabilities of Myriophyllum spicatum and Ceratophyllum demersum for Zinc,Copper and Lead

Industrial wastewaters contain various heavy metal components and therefore threaten aquatic bodies. Heavy metals can be adsorbed by living or non‐living biomass. Submerged aquatic plants can be used for the removal of heavy metals. This paper exhibits the comparison of the adsorption properties of two aquatic plants Myriophyllum spicatum and Ceratophyllum demersum for lead, zinc, and copper. The data obtained from batch studies conformed well to the Langmuir Model. Maximum adsorption capacities (q_max) were obtained for both plant species and each metal. The maximum adsorption capacities (q_max) achieved with M. spicatum were 10.37 mg/g for Cu²⁺, and 15.59 mg/g for Zn²⁺ as well as 46.49 mg/g for Pb²⁺ and with C. demersum they were 6.17 mg/g for Cu²⁺, 13.98 mg/g for Zn²⁺ and 44.8 mg/g for Pb²⁺. It was found that M. spicatum has a better adsorption capacity than C. demersum for each metal tested. Gibbs free energy and the specific surface area based on the q_max values were also determined for each metal.     

Micropropagation of <Emphasis Type="Italic">Vitex agnus-castus</Emphasis>, (Verbenaceae)—a valuable medicinal plant

This study describes in vitro shoot induction and plant regeneration from a mature apical meristem and nodal explants of the endangered medicinal shrub Vitex agnus-castus. Multiple shoots were induced directly from the axis of nodal and apical meristem explants on Murashige and Skoog (MS) medium containing 3% sucrose and different concentrations (1.0, 1.5, 2.0, and 2.5 mg/l) of 6-benzyl aminopurine (BAP) in combination with Kinetin (Kin) and α-naphthalene acetic acid (NAA), both at 0.1 mg/l. BAP and Kinetin were used as supplements to MS basal medium, either individually or in combination with auxins. The optimal concentration of BAP for inducing bud break was found to be 2.0 mg/l when Kinetin was at 0.1 mg/l. Regeneration frequency was highest for both apical meristem and nodal explants (94.5% and 90.3%, respectively) when explants were cultured on MS medium supplemented with BAP (2.0 mg/l) and Kin (0.1 mg/l). A maximum of 7.7 ± 0.4 and 6.7 ± 0.2 shoots were obtained per explant for apical meristem and nodal explants, respectively. Regenerated shoots, transferred to MS medium supplemented with either 1.0 or 1.5 mg/l BAP combined with 0.1 mg/l GA₃, showed maximum elongation of 6.7 ± 0.4 and 6.0 ± 1.3 cm in apical meristem and nodal explants, respectively. In vitro regenerated shoots transferred to half-strength MS medium supplemented with 0.1 mg/l IBA induced 90.4% of the shoots to form roots after 30–35 d of culture. Up to 80% of the regenerated shoots were successfully established in soil in the greenhouse.     

Plant regeneration through callus cultures derived from immature-cotyledon explants of oleaster (Elaeagnus angustifolia L.)

Efficient plant regeneration was achieved from callus derived from immature-cotyledon explants of oleaster (Elaeagnus angustifolia L.). Calli were obtained on MS media containing 3% sucrose and different concentrations of TDZ. The highest rate of green, compact and nodular callus was formed on MS medium supplemented with 1 mg/l of TDZ. Shoot organogenesis was achieved when the callus was transferred onto MS media containing 3% sucrose and BA alone (05–4 mg/l) or BA (0.5 and 1 mg/l) combined with NAA or IAA (0.5 and 1 mg/l). Maximum organogenesis was obtained with 1 mg/l BA in combination with 0.5 mg/l NAA. Rooting of the shoots was achieved on MS medium supplemented with 0.2 mg/l IBA. Regenerated plantlets were acclimatized and successfully transplanted to soil.