Toxic Effects Of Heavy Metals Research Articles

Effect of bacterial inoculation of strains of pseudomonas aeruginosa, alcaligenes feacalis and bacillus subtilis on germination, growth and heavy metal (cd, cr, and ni) uptake of brassica juncea

ABSTRACTBacterial inoculation may influence Brassica juncea growth and heavy metal (Ni, Cr, and Cd) accumulation. Three metal tolerant bacterial isolates (BCr3, BCd33, and BNi11) recovered from mine tailings, identified as Pseudomonas aeruginosa KP717554, Alcaligenes feacalis KP717561, and Bacillus subtilis KP717559 were used. The isolates exhibited multiple plant growth beneficial characteristics including the production of indole-3-acetic acid, hydrogen cyanide, ammonia, insoluble phosphate solubilization together with the potential to protect plants against fungal pathogens. Bacterial inoculation improved seeds germination of B. juncea plant in the presence of 0.1 mM Cr, Cd, and Ni, as compared to the control treatment. Compared with control treatment, soil inoculation with bacterial isolates significantly increased the amount of soluble heavy metals in soil by 51% (Cr), 50% (Cd), and 44% (Ni) respectively. Pot experiment of B. juncea grown in soil spiked with 100 mg kg−1 of NiCl2, 100 mg kg−1 of CdCl2, and 150 mg kg−1 of K2Cr2O7, revealed that inoculation with metal tolerant bacteria not only protected plants against the toxic effects of heavy metals, but also increased growth and metal accumulation of plants significantly. These findings suggest that such metal tolerant, plant growth promoting bacteria are valuable tools which could be used to develop bio-inoculants for enhancing the efficiency of phytoextraction.

Effects of cadmium on the cuttlefish Sepia pharaonis’ arginine kinase: unfolding kinetics integrated with computational simulations

Arginine kinase is closely associated with adaptation to environmental stresses such as high salinity and heavy metal ion levels in marine invertebrates. In this study, the effects of Cd2+ on the cuttlefish Sepia pharaonis’ arginine kinase (SPAK) were investigated. SPAK was isolated from the muscles of S. pharaonis and upon further purification, showed a single band on SDS-PAGE. Cd2+ effectively inactivated SPAK, and the double-reciprocal kinetics indicated that Cd2+ induced non-competitive inhibition of arginine and ATP. Spectrofluorometry results showed that Cd2+ induced tertiary structure changes in SPAK with the exposure of hydrophobic surfaces that directly induced SPAK aggregation. The addition of osmolytes, glycine, and proline successfully blocked SPAK aggregation and restored the conformation and activity of SPAK. Molecular dynamics simulations involving SPAK and Cd2+ showed that Cd2+ partly blocks the entrance of ATP to the active site, and this result is consistent with the experimental results showing Cd2+-induced inactivation of SPAK. These results demonstrate the effect of Cd2+ on SPAK enzymatic function and unfolding, including aggregation and the protective effects of osmolytes on SPAK folding. This study provides concrete evidence of the toxicity of Cd2+ in the context of the metabolic enzyme SPAK, and it illustrates the toxic effects of heavy metals and detoxification mechanisms in cuttlefish.

Wybrane choroby nerek związane z pracą

Infections, high temperature and many of the toxic substances can cause kidney damage. Acute kidney injury is a well known complication of some work-related diseases, e.g., lead intoxication. Chronic kidney disease can also be caused by some occupational factors. Three work-related nephropathies, in which causal connection with work has been proved, are discussed in this article. There are different risk factors of nephrolithiasis, lead nephropathy and silica nephropathy, but each of them can cause chronic kidney disease. Prevention of these nephropaties seems to be relatively simple. The principles of protection from the toxic effects of heavy metals and silica dust are very specific. The most important prevention of kidney stones is correct fluid intake. In addition to providing adequate quantities of drinking water, it is also important to educate exposed workers and assure enough rest breaks at work.

Arsenic and heavy metals health risk assessment through drinking water consumption in the Peshawar District, Pakistan

ABSTRACTThis study aimed to assess the drinking water quality and human potential health risk in Peshawar, which is the most populous district of Khyber Pakhtunkhwa Province, Pakistan. Water was randomly collected throughout Peshawar District (urban = 45 samples and rural = 29 samples). These samples were analyzed for heavy metal (As, Cd, Co, Cu, Cr, Hg, Ni, Pb, and Zn) concentrations using the atomic absorption spectrometer (Perkin Elmer, AAS-PEA-700). Heavy metal concentrations in drinking water revealed the highest pollution index (PI) values—17.80, 11.92, 7.50, and 5.70 for the Pb, Cr, Cd, and Ni, respectively. The contaminations of Cd and Pb were significantly higher (p < .05) than their maximum allowable limits set by the World Health Organization. Heavy metal contaminations in drinking water were evaluated for health risk assessment: the chronic risk or hazard quotient (HQ) and cancer risk. Results revealed that HQ values were >1 for the Cd and Pb, suggesting that the exposed human beings could be at chronic risk. Therefore, serious measures such as drinking water treatments and contamination controlling policies are needed to avoid the hazardous effects of toxic heavy metals.

Enterobacter asburiae KE17 association regulates physiological changes and mitigates the toxic effects of heavy metals in soybean.

This study aimed to elucidate the role played by Enterobacter asburiae KE17 in the growth and metabolism of soybeans during copper (100 μm Cu) and zinc (100 μm Zn) toxicity. When compared to controls, plants grown under Cu and Zn stress exhibited significantly lower growth rates, but inoculation with E. asburiae KE17 increased growth rates of stressed plants. The concentrations of plant hormones (abscisic acid and salicylic acid) and rates of lipid peroxidation were higher in plants under heavy metal stress, while total chlorophyll, carotenoid content and total polyphenol concentration were lower. While the bacterial treatment reduced the abscisic acid and salicylic acid content and lipid peroxidation rate of Cu-stressed plants, it also increased the concentration of photosynthetic pigments and total polyphenol. Moreover, the heavy metals induced increased accumulation of free amino acids such as aspartic acid, threonine, serine, glycine, alanine, leucine, isoleucine, tyrosine, proline and gamma-aminobutyric acid, while E. asburiae KE17 significantly reduced concentrations of free amino acids in metal-affected plants. Co-treatment with E. asburiae KE17 regulated nutrient uptake by enhancing nitrogen content and inhibiting Cu and Zn accumulation in soybean plants. The results of this study suggest that E. asburiae KE17 mitigates the effects of Cu and Zn stress by reprogramming plant metabolic processes.

Fucoidans of brown algae: Biosynthesis, localization, and physiological role in thallus

The issues of the structure and biosynthesis of fucose-containing sulfated polysaccharides are considered in this review; the data on the localization of fucoidans in tissues and their significance for algae are provided. Fucoidans participate in the building of cell walls and the support of their structure, as well as in extrusion of spores and gametes from reproductive organs. Due to the sulfated groups, these polysaccharides can bind cations (mainly K+, Na+, Ca2+, Mg2+) and participate in ion exchange with the environment, which facilitates adaptation of algae to water salinity fluctuations and to the toxic effects of heavy metals. Fucoidans play a substantial role in morphogenesis of zygotes of fucoid algae, as they participate in establishing the cell polarity and fixing the cell-division axis, thus determining the direction for the development of the rhizoidal and apical poles of young thalli.

Amelioration of Heavy-Metal Toxicity in Cauliflower by Application of Salicylic Acid

The important role of salicylic acid in response to different stresses is to modify and decrease the negative effects of stress. The objective of this study was to evaluate the amelioration of heavy-metal (HM) stress in cauliflower cv. Shubra by application of different concentrations of salicylic acid. In heavy-metal (cobalt, nickel, cadmium, chromium, and lead) stress, apart from appearance of visual symptoms, HM toxicity reduced dry weight and specific activity of catalase and increased the concentration of lipid peroxidation, proline, nonprotein thiol, electrolyte leakage percentage, and specific activity of peroxidase and superoxidase dismutase. Application of salicylic acid reverts back all parameters disturbed by HM stress. As opposed to other HMs, salicylic acid enhanced chromium toxicity effects in plants, showing synergism and the plants died. Application of salicylic acid (100 mM) ameliorated toxic effects of HMs to some extent, showing antagonism in cauliflower.

Toxic Effects of Heavy Metals on Bone Tissue

Toxic Effects of Heavy Metals on Bone Tissue

Combined toxic effects of heavy metals and antibiotics on a Pseudomonas fluorescens strain ZY2 isolated from swine wastewater.

A Pseudomonas fluorescens strain ZY2, isolated from swine wastewater, was used to investigate the synergistic effects of five heavy metals (Pb, Cu, Zn, Cr(VI) and Hg) on bacterial resistance to antibiotics. Results indicate that the combined effects of antibiotic type, heavy metal type and concentration were significant (p < 0.01). Cross-resistance to Hg and antibiotics was the most noticeable. Moreover, the resistance to Hg and cefradine or amoxicillin, and Cr and amoxicillin were synergistic for low heavy metal concentrations, and turned antagonistic with increasing concentrations, while the resistances to Cr or Cu and cefradine, Pb or Cu and amoxicillin, Cu and norfloxacin showed reverse effects. In addition, resistance to Zn and amoxicillin were always synergetic, while resistance to Pb and cefradine or norfloxacin, Cr or Hg and norfloxacin as well as all the heavy metals and tetracycline were antagonistic. These results indicate that bacterial resistance to antibiotics can be affected by the type and concentration of co-exposed heavy metals and may further threaten people’s health and ecological security severely via horizontal gene transfer.

Possible roles of plant sulfurtransferases in detoxification of cyanide, reactive oxygen species, selected heavy metals and arsenate.

Plants and animals have evolved various potential mechanisms to surmount the adverse effects of heavy metal toxicity. Plants possess low molecular weight compounds containing sulfhydryl groups (-SH) that actively react with toxic metals. For instance, glutathione (γ-Glu-Cys-Gly) is a sulfur-containing tripeptide thiol and a substrate of cysteine-rich phytochelatins (γ-Glu-Cys)2–11-Gly (PCs). Phytochelatins react with heavy metal ions by glutathione S-transferase in the cytosol and afterwards they are sequestered into the vacuole for degradation. Furthermore, heavy metals induce reactive oxygen species (ROS), which directly or indirectly influence metabolic processes. Reduced glutathione (GSH) attributes as an antioxidant and participates to control ROS during stress. Maintenance of the GSH/GSSG ratio is important for cellular redox balance, which is crucial for the survival of the plants. In this context, sulfurtransferases (Str), also called rhodaneses, comprise a group of enzymes widely distributed in all phyla, paving the way for the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors, at least in vitro. The best characterized in vitro reaction is the transfer of a sulfane sulfur atom from thiosulfate to cyanide, leading to the formation of sulfite and thiocyanate. Plants as well as other organisms have multi-protein families (MPF) of Str. Despite the presence of Str activities in many living organisms, their physiological role has not been clarified unambiguously. In mammals, these proteins are involved in the elimination of cyanide released from cyanogenic compounds. However, their ubiquity suggests additional physiological functions. Furthermore, it is speculated that a member of the Str family acts as arsenate reductase (AR) and is involved in arsenate detoxification. In summary, the role of Str in detoxification processes is still not well understood but seems to be a major function in the organism.

Arachnids (Aranei, Opiliones) in meadows: Response to pollution with emissions from the Middle Ural Copper Smelter

Arachnids living in the herbaceous layer have been studied in 2006–2008 in secondary upland meadows along the gradient of pollution with emissions from the Middle Ural Copper Smelter (Revda, Sverdlovsk oblast). It has been shown that absolute abundance and general diversity decrease with increasing levels of technogenic pressure. Direct toxic effect of heavy metals is especially strong on taxa closely associated with soil and litter; this effect is the most likely cause of the absence of harvestmen near the smelter. The other groups of arachnids are more strongly affected by environmental changes (depletion of species diversity, simplification of architecture of the herbaceous layer, and modification of the hydrothermal regime of this layer) indirectly caused by pollution.

Auxin-mediated growth of rice in cadmium-contaminated soil

Pollution from heavy metals is a global problem that is very dangerous to the environment. Among the heavy metals, cadmium is receiving more and more attention because it is one of the most ecotoxic, making it very harmful for biological activity in soil, biodiversity, plant metabolism, and human and animal health. Phytohormones, produced by plants, control or regulate germination, growth, metabolism, or other physiological activities, and they can alleviate the toxic effects of heavy metals on plant growth. Auxin is the most abundant natural growth hormone, controlling apical dominance, tropism, elongation of shoots, and initiation of roots in plants. However, cadmium stress causes the degradation of indigenous auxin. To cope with this, auxin may be applied exogenously. To evaluate the role of auxin in cadmium -contaminated soil, different levels of the auxin precursor L-TRP were applied to plants growing in contaminated soil. Rice seedlings were dipped in a L-TRP solution for 2 h and transplanted into potted soil contaminated with 30 mg kg1 cadmium. The results showed that the exogenous application of L-TRP improved the growth and yield of treated plants both in normal and contaminated soil. The data of different parameters showed that L-TRP enhanced plant height (12.54%), the number of tillers (25.53%), the number of panicles (19.04%), the 1000 grain weight (19.28%), and the paddy yield (11.78%) in cadmium-contaminated soil, as compared to plants grown in the absence of L-TRP with the same level of contamination. L-TRP increased the uptake of cadmium in rice straw while decreasing the translocation of cadmium towards grains, as compared to plants grown in contaminated soil without L-TRP. This experiment revealed the possibility of using L-TRP to improve plant growth and soil health in contaminated soil.

Differential responses of one hundred tomato genotypes grown under cadmium stress

Due to increased global concern over the deleterious effects of toxic heavy metals in the environment, it has become necessary to develop plant genotypes that limit the uptake of heavy metals to aerial edible parts. To address this concern, we performed a glasshouse experiment to assess variations within tomato germplasm for cadmium (Cd) tolerance under control conditions and under simulated stress conditions. Significant differences (P < 0.01) were observed among all genotypes at both Cd levels (3 ppm and 6 ppm). Our analyses showed that the genotypes 9086, Roma, Sitara TS-01, pak0010990, CLN-2123A, Picdeneato, 0.006231, and 7035 gave the best yields with minimum Cd content in their fruit, whereas the genotypes 42-07, 17883, BL-1176-Riostone-1-1, Marmande, and 17882 had relatively low yields with higher metal contents. The heavy metal was found to accumulate first in the shoot, then fruit, leaf, and finally root in tolerant genotypes; in susceptible genotypes, the order was fruit, shoot, leaf, and root. The inter-genotype differences in Cd uptake indicated the possibility of manipulating tomato genotypes to develop Cd tolerant tomato varieties or hybrids that allow safe use of a tomato crop grown on Cd contaminated soils.

Use of Fish as Bio-indicator of the Effects of Heavy Metals Pollution

The present review gives a brief account of the toxic effects of heavy metals on fish. In aquatic ecosystem, heavy metals are considered as the most important pollutants, since they are present throughout the ecosystem and are detectable in critical amounts. Heavy metals, such as mercury, cadmium, copper, lead and zinc are of the most important pollutants which effect aquatic environment and fish. They are extremely dangerous for the health of fish. Most of these metals are characterized by being accumulated in tissues, and lead to the poisoning of fish. These metals can effectively influence the vital operations and reproduction of fish; weaken the immune system, and induce pathological changes. As such, fish are used as bio-indictors, playing an important role in monitoring heavy metals pollution. Finally, some recommendations are given to treatment of different kinds of wastewaters, sewage and agricultural wastes before discharge into the aquatic systems. Also, enforcement of laws and legislations regarding the protection of aquatic environments must be taken into consideration.

Biogas production as affected by heavy metals in the anaerobic digestion of sludge

Biogas production can be generated by sludge digestion process in the form of methane which in some plants is collected and used as a source of energy. Sewage which is collected from mixed industrial and domestic population may be contaminated with metals and industrial chemicals. The aim of the present study is to investigate the effect of heavy metals on the biogas production in the anaerobic digestion process for the treatment of sewage sludge. The selected metals are Hg, Cd and Cr III. The toxic effect and the inhibitory impact of the digestion process are among the objective of the study. The fate and toxic effects of heavy metals on the biogas production was determined.The sewage sludge samples were separated from the sewage water of the pilot plant at the National Research Centre, TDC site. The effect of heavy metals on the biogas production of the anaerobic digester was studied. The inhibitory effect on the biogas production and toxic level of metals was determined in this study. The general ranking of heavy metal toxicity appears to be Hg>Cd>Cr (III). The present investigation reveals that heavy metals in addition to the anaerobic digester decreased the biogas production as an indication of efficiency of the process. A significant decrease in gas production and volatile organic matter removal was obtained. It was also noted that an accumulation of organic acid intermediates was obtained as a result of methanogenic bacterial inhibition. This accumulation was limited during the pulse feed of metals. This is due to the rapid poisoning of the active bacterial forms in the digester.

Differential responses of three sweetpotato metallothionein genes to abiotic stress and heavy metals.

Metallothioneins (MTs) are cysteine-rich, low molecular weight, metal-binding proteins that are widely distributed in living organisms. Plants produce metal-chelating proteins such as MTs to overcome the toxic effects of heavy metals. We cloned three MT genes from sweetpotato leaves [Ipomoea batatas (L.) Lam.]. The three IbMT genes were classified according to their cysteine residue alignment into type 1 (IbMT1), type 2 (IbMT2), and type 3 (IbMT3). IbMT1 was the most abundantly transcribed MT. It was predominantly expressed in leaves, roots, and callus. IbMT2 transcript was detected only in stems and fibrous roots, whereas IbMT3 was strongly expressed in leaves and stems. The IbMT expression profiles were investigated in plants exposed to heavy metals and abiotic stresses. The levels of IbMT1 expression were strongly elevated in response to Cd and Fe, and moderately higher in response to Cu. The IbMT3 expression pattern in response to heavy metals was similar to that of IbMT1. Exposure to abiotic stresses such as methyl viologen (MV; paraquat), NaCl, polyethylene glycol (PEG), and H2O2 up-regulated IbMT expression; IbMT1 responded strongly to MV and NaCl, whereas IbMT3 was induced by low temperature and PEG. Transgenic Escherichia coli overexpressing IbMT1 protein exhibited results suggest that IbMT could be a useful tool for engineering plants with enhanced tolerance to environmental stresses and heavy metals.

Environmental safety level of lead (Pb) pertaining to toxic effects on grey mullet (Mugil cephalus) and tiger perch (Terapon jarbua).

Acute and chronic bioassay toxicity test of Lead (Pb) in Grey Mullet (Mugil cephalus), and Tiger perch (Terapon jarbua) was conducted. LC50 values (Lethal Concentration) from acute tests and chronic values were calculated by the geometric mean of the No-Observed-Effect Concentration (NOEC) and the Lowest-Observed-Effect Concentration (LOEC) in a study period of 30 days. This research was conducted to evaluate the quantitative relationship between toxicity test statistics and correlation between toxicant and the organisms exposed. Three test average LC50 was analyzed for 24, 48, 72, and 96 h and the 96 h average LC50 of M. cephalus and T. jarbua is 2.57 ± 0.47 and 2.99 ± 0.23 mg/L of Pb, respectively. Significant correlation is observed with the increased time duration and exposure concentration. The NOEC and LOEC values were calculated based on survival of test organisms for M. cephalus and T. jarbua and the values are 0.014 and 0.029 and 0.011 and 0.022 mg/L, respectively. The chronic value is found to be 0.011 mg/L for M. cephalus and 0.021 mg/L for T. jarbua. The intensity of biochemical and histological alterations increased gradually with increased Pb concentration and the exposure time. Toxicity testing is the primary step to determine the water quality safe limit on marine organisms. The outcome of the study indicates that the sensitivity of juvenile organisms to Pb, persistence of toxic effects and biomarkers as a tool capable of revealing the toxic effects of heavy metals on the environment and aquatic biota.

Effects of heavy metals toxicity on the biochemical response in tomato plants grown in contaminated silt-soil

Toxic effects of Cu2+, Zn2+ and Cd2+ in tomato plants were the reduction in vegetative growth of seedlings and also in flowering and fruiting. Toxicity of these heavy metals resulted in a reduction in chlorophyll a, chlorophyll b and soluble sugars, but in an increase in proline. Toxic metal stress caused a 71.71, 77.70 and 11.90% increase in the activities of peroxidase, catalase and ascorbic acid oxidase, respectively. With respect to the total uptake of Cd2+, the biggest sink for the metal was provided by roots with 72.80% retention followed by 22% in the stem. Accumulation of Cd2+ and Zn2+ gradually increased in the order of root, stem and leaves, but for Cu2+ that was reversed, that is, it increased in the order of leaf, stem and root. A new consideration of metals bioavailability is discussed in terms of their respective solubility product constants, pH of precipitation, and metal complexation. DOI: http://dx.doi.org/10.3329/bjsir.v48i4.9754 Bangladesh J. Sci. Ind. Res. 48(4), 229-236, 2013

Fibroblasts From Long-Lived Rodent Species Exclude Cadmium

Resistance to the lethal effects of cellular stressors, including the toxic heavy metal cadmium (Cd), is characteristic of fibroblast cell lines derived from long-lived bird and rodent species, as well as cell lines from several varieties of long-lived mutant mice. To explore the mechanism of resistance to Cd, we used inductively coupled plasma mass spectroscopy to measure the rate of Cd uptake into primary fibroblasts of 15 rodent species. These data indicate that fibroblasts from long-lived rodent species have slower rates of Cd uptake from the extracellular medium than those from short-lived species. In addition, fibroblasts from short-lived species export more zinc after exposure to extracellular Cd than cells from long-lived species. Lastly, fibroblasts from long-lived rodent species have lower baseline concentrations of two redox-active metals, iron and copper. Our results suggest that evolution of longevity among rodents required adjustment of cellular properties to alter metal homeostasis and to reduce the toxic effects of heavy metals that accumulate over the course of a longer life span.

Whole Cell-based Biosensors for Environmental Heavy Metals Detection

Biosensors have emerged as new alternatives in environmental toxicity assessment. In the development of biosensors for heavy metals detection in environment, whole cells are highly favored as these cells are able to reflect the real toxicity effects of heavy metals to living organisms. For heavy metals detection, the integration of several types of cells such as bacteria, cyanobacteria, and algae into biosensors development has been widely reported. The usage of other cells such as plant cell, protozoa, and yeast has been reported as well. Although these biosensors are highly sensitive to heavy metals, the detection is still limited to the heavy metals which are bioavailable to the cells. Besides, the response of whole cells to wide range of heavy metals makes them excellent tools for wide spectrum screening but lack of specificity in detection. Whole cells are living entities with complex biochemical processes, which make the optimization of whole cell-based biosensors a tedious process, while maintaining the stability and storability are still challenging tasks. Although naturally occurring cells are highly favored, some reports show that recombinant cells can be a choice with better performance. In this paper, the usage of whole cells in biosensors for heavy metals detection and some of the current issues which are tied to the development of these biosensors are reviewed.