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1.
The influence of copper (II) ions on the growth, accumulation properties and superoxide dismutase (SOD) activity of a growing culture of Aspergillus niger B-77 were studied. Microbial growth, the level of copper (II) accumulation and SOD activity depended on the initial copper (II) concentration. Aspergillus niger is able to accumulate large amounts of copper (II) from the nutrient medium with 200 mg x l(-1) copper (II) ions without loosing its biological activities. Addition of copper (II) ions increased the SOD activity in the growing cell cultures. The changes in enzyme activity induced by heavy metal ions might be used as an indicator of intracellular oxy-intermediate generation in a cell culture growing under stress conditions.  相似文献   

2.
Aims:  To investigate the relationship between growth, heavy metal ions uptake and participation of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in the protection of Apergillus niger B 77 against cadmium stress.
Methods and Results:  The stress response of the model fungal strain, under conditions of a wide range of Cd (II) ion concentrations, was investigated by determining the biomass formation, protein biosynthesis, SOD and CAT activities and heavy metal uptake in growing cells. Exposure to heavy metal ions induced an increase in protein content, heavy metal uptake and SOD activity, and a heavy decrease in CAT activity.
Conclusion:  The results obtained indicated that the tolerance of A. niger to Cd (II) was correlated with the heavy metal uptake, reactive oxygen species generation in the cells and the efficiency of antioxidative defence system.
Significance and Impact of the Study:  Evidence is provided for the possibility that oxidative stress plays a major role in the effect of Cd (II) ions on A. niger . These data could offer useful information when creating new strategies and methodological improvements for bioremediation with the participation of fungi.  相似文献   

3.
The effect of copper(II), lead(II) and chromium(VI) ions on the growth and bioaccumulation properties of Aspergillus niger was investigated as a function of initial pH and initial metal ion concentration. The optimum pH values for growth and metal ion accumulation were determined as 5.0, 4.5 and 3.5 for copper(II), lead(II) and chromium(VI) ions, respectively. Although all metal ion concentrations caused an inhibition effect on the growth of A. niger, it was capable of removing of copper(II) and lead(II) with a maximum specific uptake capacity of 15.6 and 34.4 mg g−1 at 100 mg dm−3 initial copper(II) and lead(II) concentration, respectively. Growth of A. niger was highly effected by chromium(VI) ions and inhibited by 75 mg dm−3 initial chromium(VI) concentration since some inhibition occurred at lower concentrations.  相似文献   

4.
Copper accumulation and phosphatase activities of three Aspergillus species resistant to copper were compared to three copper-sensitive Rhizopus species. High level of acid phosphatases and decreased Cu2+-uptake were found with resistant in contrast to sensitive strains. The presence of copper(II) ions in the medium increased the production of acid phosphatases in the resistant A. niger and decreased their activity in the sensitive R. delemar. Copper ions inhibited the activity of A. niger cellular acid phosphatase with a Ki of 8.9x10(-4) M and slightly activated the R. delemar enzyme.  相似文献   

5.
To obtain information on the importance of membrane and zeta potentials as repelling or facilitating forces during the uptake of cationic trace elements, the heavy metal content and the growth resistance of the acidotolerant fungus Bispora. sp. to heavy metals were compared at pH 1.0 and pH 7.0. Cu, Co, Ni, Cd, Cr, and La contents of the fungus were significantly lower at pH 1.0 than at pH 7.0. A similar pH effect occurred with cationic macro elements such as Na, Mg, Ca, Fe, and Mn. Only K and Zn exhibited higher levels at pH 1.0 in the fungus than at pH 7.0. Macro and micro elements present in the medium in anionic form (sulfate, chloride) showed the opposite pattern to cations: Contents were higher at pH 1.0 than at pH 7.0. Minerals present at pH 1.0 predominantly in the electrical neutral, protonated form (phosphate, borate) exhibited a similar cell content at both acid and neutral pH (P) or a higher content at neutral pH than at acid pH (B). The resistance of fungal growth to the cations Cu, Zn, Ni, Co, Cr, and Cd was significantly higher at pH 1.0 than at pH 7.0. Such a difference was not observed with Hg, present in the medium at both pH values as electrically silent HgCl2. The anionic tungstate exhibited the opposite pattern to cationic heavy metals: The resistance of growth was higher at pH 7.0 than at pH 1.0. A greater growth resistance to heavy metals was correlated with a lower uptake of these elements, and vice versa; Uptake of heavy metals correlated with a lower resistance of fungal growth to these elements. The results are in agreement with the hypothesis that membrane and zeta potentials of the fungus are important factors controlling the uptake of heavy metals and thereby the resistance of growth to these elements: At pH 1.0 positive potentials of fungal hyphae impede the uptake of cationic heavy metals, but facilitate the uptake of anionic species. At neutral pH values the negative potentials facilitate the uptake of cations, but impede the uptake of anions.  相似文献   

6.
The effect of copper (II) ions on the growth of three brown-rot fungi, six white-rot fungi and one blue-stain fungus in solid medium was evaluated. The fungi were grown in malt extract agar with different concentrations of copper added, and the radial growth rate was determined. At the end of the incubation period, the mycelial biomass and the media pH were determined. The white-rot and blue-stain fungus grew up to 3 mM and 6 mM copper, respectively and the brown-rot fungi were the only ones that grew up to 10 mM, with higher growth rates than those shown by the other fungi. In general, the brown-rot fungi produced greater acidification in the culture media than the white-rot fungi and blue-stain fungus, and the acidification increased when the amount of copper was increased. The biomass production for the different species, in the absence or presence of copper, was not related to the radial growth rate, and the fungal species that produced the greatest biomass amounts did not correspond to those that presented the highest growth rates. The brown-rot fungi Wolfiporia cocos and Laetiporus sulfureus and blue-stain fungus Ophiostoma sp. demonstrated greater tolerance to high copper concentrations in solid medium than the white-rot fungi, determined as radial growth rate. On the other hand, the highest biomass producers in solid medium with copper added were the white-rot fungi Ganoderma australe and Trametes versicolor and the brown-rot fungus Gloeophyllum trabeum.  相似文献   

7.
Previously, it has been suggested that melanoidin-like products (MLP) from sugarcane molasses may accelerate copper phytoextraction. In this study, we evaluated the facilitatory effect of MLP on phytoextraction in a medium including cadmium or lead, the concentrations of which were adjusted around the regulation values of the Soil Contamination Countermeasures Act in Japan. Three Brassica species were tested based on their fast growth, high biomass productivity, and high heavy metal absorption. Both biomass and lead uptake in the nutrient medium with 1 mM lead nitrate were significantly increased by the addition of MLP, and almost all of the lead was accumulated in the root tissue. Therefore, MLP were able both to detoxify lead ions and to improve their bioavailability in Brassica species. In contrast, only these species with MLP or citric acid survived in the nutrient medium with 1 mM cadmium sulfate. The phytoextraction of cadmium using these species was therefore impractical under the Act.  相似文献   

8.
The ciliate, Euplotes mutabilis, isolated from industrial wastewater of tanneries of Kasur, Pakistan, showed tolerance against Cd2+ (22 microg ml(-1)), Cr6+ (60 microg ml(-1)), Pb2+ (75 microg ml(-1)) and Cu2+ (22 microg ml(-1)). The heavy metals, Cr and Pb, were randomly selected for determining the capability of the ciliate to reduce the concentration of these metal ions in the medium and to evaluate its potential use as bioremediator of wastewater. The live protozoans could remove 97% of Pb2+ and 98% of Cr6+ from the medium, 96 h after inoculation of the medium containing 10 micro gml(-1) of metal ions. The acid digestion of ciliate showed 89% of Pb2+ and 93% of Cr6+ ions accumulated in the organism. When the ciliate was exposed to heavy metals at a larger scale viz., 10 l of water containing 10 micro gml(-1) of heavy metals, it removed 86% of Pb2+ and 90% of Cr6+ from the medium. The metal uptake ability of E. mutabilis, as evidenced by its survival and growth in 100ml and 10 l of water containing 10 microg ml(-1) of metal ions, reduction in the concentration of heavy metals in the medium and its increased uptake by the live cells, and no metal uptake by the heat killed ciliate can be exploited for metal detoxification of industrial wastes and environmental clean-up operations.  相似文献   

9.
The potential use of the immobilized fresh water algae (in Ca-alginate) of Scenedesmus quadricauda to remove Cu(II), Zn(II) and Ni(II) ions from aqueous solutions was evaluated using Ca-alginate beads as a control system. Ca-alginate beads containing immobilized algae were incubated for the uniform growth at 22 degrees C for 5d ays. Adsorption of Cu(II), Zn(II) and Ni(II) ions on the immobilized algae showed highest values at around pH 5.0. Adsorption of Cu(II), Zn(II) and Ni(II) ions on the immobilized algae increased as the initial concentration of metal ions increased in the medium. The maximum adsorption capacities of the immobilized algal biosorbents for Cu(II), Zn(II) and Ni(II) were 75.6, 55.2 and 30.4 mg/g (or 1.155, 0.933 and 0.465 mmol/g) biosorbent, respectively. When the heavy metal ions were in competition, the amounts of adsorbed metal ions were found to be 0.84 mol/g for Cu(II), 0.59 mol/g for Ni(II) and 0.08 mol/g for Zn(II), the immobilised algal biomass was significantly selective for Cu(II) ions. The adsorption-equilibrium was also represented with Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms. The adsorption of Cu(II), Zn(II) and Ni(II) ions on the immobilized algae followed second-order kinetic.  相似文献   

10.
Aspects of the utilization of copper by the fungus, Dactylium dendroides, have been studied. The organism grows normally at copper levels below 10 nM. Cells grown in medium containing 30 nM copper or less concentrate exogenous metal at all levels of added copper; copper uptake is essentially complete within 15 min and is not inhibited by cycloheximide, dinitrophenol or cyanide. These results indicate that copper absorption is not an energy-dependent process. The relationship between fungal copper status and the activities of three copper-containing enzymes, galactose oxidase, and extracellular enzyme, the cytosolic, Cu/Zn superoxide dismutase and cytochrome oxidase, has also been established. The synthesis of galactose oxidase protein (holoenzyme plus apo-enzyme) is independent of copper concentration. Cells grown in copper-free medium (less than 10 nM copper) excrete normal amounts of galactose oxidase as an apoprotein. At medium copper levels below 5 micrometer, new cultures contain enough total copper to enable the limited number of cells to attain sufficient intracellular copper to support hologalactose oxidase production. As a result of cell division, however, the amount of copper available per cell drops to a threshold of approx. 10 ng/mg below which point only apogalactose oxidase is secreted. Above 5 micrometer medium copper, holoenzyme secretion is maintained throughout cell growth. The levels of the Cu/Zn superoxide dismutase respond differently in that the protein itself apparently is synthesized in only limited amounts in copper-depleted cells. Total cellular superoxide dismutase activity is maintained under such conditions by an increase in activity associated with the mitochondrial, CN(-)-insensitive, manganese form of this enzyme. Cells grown at 10 micrometer copper show 83% of their superoxide dismutase activity to be contributed by the Cu/Zn form compared to a 17% contribution to the total activity in cells grown at 30 nM copper, indicating that the biosynthesis of the Cu/Zn and Mn-containing enzymes is coordinated. The data show that the level of copper modulates the synthesis of the cytosolic superoxide dismutase. In contrast, the cytochrome oxidase activity of D. dendroides is independent of cellular copper levels obtainable. Thus, the data also suggest that these three enzymes utilize different cellular copper pools. As cells are depleted of copper by cell division, the available copper is used to maintain Cu/Zn superoxide dismutase and cytochrome oxidase activity; at very low levels of copper, only the latter activity is maintained. The induction of the manganisuperoxide dismutase in copper-depleted cells should have practical value in the isolation of this protein.  相似文献   

11.
Biosorption of each of the heavy metals, copper(II) and cobalt(II) by crab shell was investigated in this study. The biosorption capacities of crab shell for copper and cobalt were studied at different particle sizes (0.456-1.117 mm), biosorbent dosages (1-10 g/l), initial metal concentrations (500-2000 mg/l) and solution pH values (3.5-6) in batch mode. At optimum particle size (0.767 mm), biosorbent dosage (5 g/l) and initial solution pH (pH 6); crab shell recorded maximum copper and cobalt uptakes of 243.9 and 322.6 mg/g, respectively, according to Langmuir model. The kinetic data obtained at different initial metal concentrations indicated that biosorption rate was fast and most of the process was completed within 2h, followed by slow attainment of equilibrium. Pseudo-second order model fitted the data well with very high correlation coefficients (>0.998). The presence of light and heavy metal ions influenced the copper and cobalt uptake potential of crab shell. Among several eluting agents, EDTA (pH 3.5, in HCl) performed well and also caused low biosorbent damage. The biosorbent was successfully regenerated and reused for five cycles.  相似文献   

12.
Glyoxalase II is a hydrolytic enzyme part of the glyoxalase system, responsible for detoxifying several cytotoxic compounds employing glutathione. Glyoxalase II belongs to the superfamily of metallo-beta-lactamases, with a conserved motif able to bind up to two metal ions in their active sites, generally zinc. Instead, several eukaryotic glyoxalases II have been characterized with different ratios of iron, zinc, and manganese ions. We have expressed a gene coding for a putative member of this enzyme superfamily from Salmonella typhimurium that we demonstrate, on the basis of its activity, to be a glyoxalase II, named GloB. Recombinant GloB expressed in Escherichia coli was purified with variable amounts of iron, zinc, and manganese. All forms display similar activities, as can be shown from protein expression in minimal medium supplemented with specific metal ions. The crystal structure of GloB solved at 1.4 A shows a protein fold and active site similar to those of its eukaryotic homologues. NMR and EPR experiments also reveal a conserved electronic structure at the metal site. GloB is therefore able to accommodate these different metal ions and to carry out the hydrolytic reaction with similar efficiencies in all cases. The metal promiscuity of this enzyme (in contrast to other members of the same superfamily) can be accounted for by the presence of a conserved Asp residue acting as a second-shell ligand that is expected to increase the hardness of the metal binding site, therefore favoring iron uptake in glyoxalases II.  相似文献   

13.
In this study, bioaccumulation of heavy metal and dye by Aspergillus versicolor was investigated. Optimum pH values of the maximum heavy metal bioaccumulation was found as 6 for 50 mg/L Cr(VI), Ni(II) and 5 for Cu(II) ions with the 99.89%, 30.05% and 29.06% removal yield, respectively. The bioremoval of the dye up to 800 mg/L at pH 5 and 6 was investigated and 27.15% and 28.95% removal rates were measured respectively. The presence of Cr(VI) with dye, decreased the uptake yield for both pollutants. In the medium with Cu(II) and dye, dye removal was not affected by Cu(II), but Cu(II) removal rate increased from 29.06% to 37.91% by the existence of the dye. When Ni(II) and dye were combined, neither pollutant affected the other’s removal yield. These results indicate that the isolated A. versicolor strain deserves attention as a promising bioaccumulator of heavy metal ions and reactive dyes in wastewater effluents.  相似文献   

14.
Whole body homeostasis can be viewed as the balance between absorption and excretion, which can be regulated independently. Present evidence suggests that for iron, intestinal absorption is the main site for homeostatic regulation, while for copper it is biliary excretion. There are connections between iron and copper in intestinal absorption and transport. The blue copper plasma protein, ceruloplasmin, and its intracellular homologue, hephaestin, play a role in cellular iron release. The studies reviewed here compare effects of Fe(II) and Cu(II) on their uptake and overall transport by monolayers of polarized Caco2 cells, which model intestinal mucosa. In the physiological range of concentrations, depletion of cellular iron or copper (by half) increased uptake of both metal ions. Depletion of iron or copper also enhanced overall transport of iron from the apical to the basal chamber. Copper depletion enhanced overall copper transport, but iron depletion did not. Pretreatment with excess copper also stimulated copper absorption. Plasma ceruloplasmin (added to the basal chamber) failed to enhance basolateral iron release, and Zn(II) failed to compete with Cu(II) for uptake. Neither copper nor iron deficiency altered expression of IREG1 or DMT1 (-IRE form) at the mRNA level. Thus, in the low-normal range of iron and copper availability, intestinal absorption of both metals appears to be positively related to the need for these elements by the whole organism. The two metal ions also influenced each other's transport; but with copper excess, other mechanisms come into play.  相似文献   

15.
Jonak C  Nakagami H  Hirt H 《Plant physiology》2004,136(2):3276-3283
Excessive amounts of heavy metals adversely affect plant growth and development. Whereas some regions naturally contain high levels of heavy metals, anthropogenic release of heavy metals into the environment continuously increases soil contamination. The presence of elevated levels of heavy metal ions triggers a wide range of cellular responses including changes in gene expression and synthesis of metal-detoxifying peptides. To elucidate signal transduction events leading to the cellular response to heavy metal stress we analyzed protein phosphorylation induced by elevated levels of copper and cadmium ions as examples for heavy metals with different physiochemical properties and functions. Exposure of alfalfa (Medicago sativa) seedlings to excess copper or cadmium ions activated four distinct mitogen-activated protein kinases (MAPKs): SIMK, MMK2, MMK3, and SAMK. Comparison of the kinetics of MAPK activation revealed that SIMK, MMK2, MMK3, and SAMK are very rapidly activated by copper ions, while cadmium ions induced delayed MAPK activation. In protoplasts, the MAPK kinase SIMKK specifically mediated activation of SIMK and SAMK but not of MMK2 and MMK3. Moreover, SIMKK only conveyed MAPK activation by CuCl(2) but not by CdCl(2). These results suggest that plants respond to heavy metal stress by induction of several distinct MAPK pathways and that excess amounts of copper and cadmium ions induce different cellular signaling mechanisms in roots.  相似文献   

16.
Aspects of the utilization of copper by the fungus, Dactytium dendroides, have been studied. The organism grows normally at copper levels below 10 nM. Cells grown in medium containing 30 nM copper or less concentrate exogenous metal at all levels of added copper; copper uptake is essentially complete within 15 min and is not inhibited by cycloheximide, dinitrophenol or cyanide. These results indicate that copper absorption is not an energy-dependent process. The relationship between fungal copper status and the activities of three copper-containing enzymes, galactose oxidase, an extracellular enzyme, the cytosolic, Cu/Zn superoxide dismutase and cytochrome oxidase, has also been established. The synthesis of galactose oxidase protein (haloenzyme plus apo-enzyme) is independent of copper concentration. Cells grown in copper-free medium (< 10 nM copper) excrete normal amounts of galactose oxidase as an apoprotein. At medium copper levels below 5 μM, new cultures contain enough total copper to enable the limited number of cells to attain sufficient intracellular copper to support hologalactose oxidase production. As a result of cell division, however, the amount of copper available per cell drops to a threshold of approx. 10 ng/mg below which point only apogalactose oxidase is secreted. Above 5 μM medium copper, holoenzyme secretion is maintained throughout cell growth.The levels of the Cu/Zn superoxide dismutase respond differently in that the protein itself apparently is synthesized in only limited amounts in copper-depleted cells. Total cellular superoxide dismutase activity is maintained under such conditions by an increase in activity associated with the mitochondrial, CN?-insensitive, manganese form of this enzyme. Cells grown at 10 μM copper shown 83% of their superoxide dismutase activity to be contributed by the Cu/Zn form compared to a 17% contribution to the total activity in cells grown at 30 nM copper, indicating that the biosynthesis of the Cu/Zn and Mn-containing enzymes is coordinated. The data show that the level of copper modulates the synthesis of the cytosolic superoxide dismutase. In contrast, the cytochrome oxidase activity of D. dendroides is independent of cellular copper levels obtainable. Thus, the data also suggest that these three enzymes utilize different cellular copper pools. As cells are depleted of copper by cell division, the available copper is used to maintain Cu/Zn superoxide dismutase and cytochrome oxidase activity; at very low levels of copper, only the latter activity is maintained. The induction of the manganisuperoxide dismutase in copper-depleted cells should have practical value in the isolation of this protein.  相似文献   

17.
Acid pretreatment of cellulosic wastes improved their susceptibility to Fusarium acuminatum enzymes. The effectiveness of acid pretreatment was demonstrated with an increase in both fungal growth and enzyme activities. A growth yield of 0.15 g/100 ml was achieved on medium containing 5% acid pretreated pods of bean for 60 minutes. Avicelase (C1), carboxymethylcellulase (Cx) and B-glucosidase (C2) reached their maximal biosynthesis on acid pretreated wheat bran, sugar-cane bagasse and sawdust-containing media, respectively. Xylanase and pectinase attained their highest accumulation on pretreated pods of bean media. A mixture of free sugars has been released by acid pretreatment. O.199 g dry mycelium was obtained when the fungus was grown on 100 ml of medium containing hydrolysate of 10% H2SO4 pretreated pods of bean for 30 min. No cellulase enzymes could be detected on hydrolysate medium at the time that low contents of both xylanase and pectinase were accumulated.  相似文献   

18.
Biosorption is an innovative and alternative technology to remove heavy metal pollutants from aqueous solution using live, inactive and dead biomasses such as algae, bacteria and fungi. In this study, live and dried biomass of Phanerochaete chrysosporium and Funalia trogii was applied as heavy metal adsorbent material. Biosorption of copper(II) cations in aqueous solution by live and dried biomass of Phanerochaete chrysosporium and Funalia trogii was investigated to study the effects of initial heavy metal concentration, pH, temperature, contact time, agitation rate and amount of fungus. Copper(II) was taken up quickly by fungal biomass (live or dried) during the first 15 min and the most important factor which affected the copper adsorption by live and dried biomass was the pH value. An initial pH of around 5.0 allowed for an optimum adsorption performance. Live biomass of two white rot fungi showed a high copper adsorption capacity compared with dried biomass. Copper(II) uptake was found to be independent of temperature in the range of 20–45 °C. The initial metal ion concentration (10–300 mg/L) significantly influenced the biosorption capacity of these fungi. The results indicate that a biosorption as high as 40–60 % by live and dried biomass can be obtained under optimum conditions.  相似文献   

19.
Stable mutants of Aspergillus nidulans, resistant to 1 mM Ni were developed by step-by-step repeated culturing of the fungus on the medium containing increasing concentrations of nickel chloride. Characterization of mutants could differentiate them into two categories NiR I and NiR II. Each category of mutants exhibited alterations in growth, conidial germination and melanin secretion both in Ni-free and Ni-containing media. NiR II mutants were little slow in growth with sparse mycelia and conidiation but showed high melanin secretion and higher Ni-uptake in comparison to NiR I mutant. Studies involving metabolic and translational inhibitors could prove that Ni-accumulation was biphasic. The initial energy independent surface accumulation was found to be followed by energy dependent intarcellular uptake. Increase in the concentration of the metal in the medium or the time of exposure did not proportionately increase the metal uptake by the mutants. Ni-uptake followed Michaelis-Menton saturation kinetics, which was enhanced under optimum pH of 6.5–7.5 and reduced complexity of the medium due to free availability of ions. Resistance to Ni was found to be constitutive in NiRI mutant, and could be induced in NiRII mutant.  相似文献   

20.
Lactic acid bacteria (LAB) as starter culture in food industry must be suitable for large-scale industrial production and possess the ability to survive in unfavorable processes and storage conditions. Approaches taken to address these problems include the selection of stress-resistant strains. In food industry, LAB are often exposed to metal ions induced stress. The interactions between LAB and metal ions are very poorly investigated. Because of that, the influence of non-toxic, toxic and antioxidant metal ions (Zn, Cu, and Mn) on growth, acid production, metal ions binding capacity of wild and adapted species of Leuconostoc mesenteroides L3, Lactobacillus brevis L62 and Lactobacillus plantarum L73 were investigated. The proteomic approach was applied to clarify how the LAB cells, especially the adapted ones, protect themselves and tolerate high concentrations of toxic metal ions. Results have shown that Zn and Mn addition into MRS medium in the investigated concentrations did not have effect on the bacterial growth and acid production, while copper ions were highly toxic, especially in static conditions. Leuc. mesenteroides L3 was the most efficient in Zn binding processes among the chosen LAB species, while L. plantarum L73 accumulated the highest concentration of Mn. L. brevis L62 was the most copper resistant species. Adaptation had a positive effect on growth and acid production of all species in the presence of copper. However, the adapted species incorporated less metal ions than the wild species. The exception was adapted L. brevis L62 that accumulated high concentration of copper ions in static conditions. The obtained results showed that L. brevis L62 is highly tolerant to copper ions, which allows its use as starter culture in fermentative processes in media with high concentration of copper ions.  相似文献   

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