Toxic Effects Of Heavy Metals Research Articles

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.

Pilot plant studies for the removal of heavy metals from industrial wastewater using adsorbents

Due to carcinogenic and toxic effects of heavy metals on the environment and living beings, the necessity of proper removal systems for these harmful elements is obvious. Additionally, conventional methods in wastewater treatment are mainly biological; therefore, removal of heavy metals should occur by using adsorbents. In this study, activated carbon along with other cheap and available materials such as sawdust and bentonite in seven different adsorbent mixtures is applied to remove heavy metals from wastewater. Wastewater was applied to the system with a flow rate of $0.2\, \frac{L}{min}$. Assuming fixed pH, biochemical oxygen demand, chemical oxygen demand, and total suspended solids, amounts of Fe, Mn, Cu, Al, and Mg from the wastewater were measured. Finally, adsorption capacity results were analyzed according to Langmuir and Freundlich theories for each mixture of adsorbents. Based on the results, sawdust is introduced as a desirable adsorbent for most heavy metals. For each element, an optimized adsorbent is also suggested, which, due to similar atomic and cationic properties, can be generalized for other similar elements.

Influence of compost from fish by-products on nutrient supply in radish

The interest in the subject of trace element concentrations and their behaviour in the environment is increasing, therefore investigations focused at determining abilities for harmful metals accumulation in plants growing on soil permanently or freshly polluted with heavy metals, contribute to development of this area of research. The paper aimed at an assessment of yielding and accumulation of zinc in buckwheat (Fagopyrum esculentum Moench) and sunflower (Helianthus annuus L.) cultivated on soils at various times polluted with this metal. Much lower yields of buckwheat and sunflower were obtained on light soils, irrespective of supplementary mineral fertilization or the level and date of soil pollution with heavy metals. A toxic effect of heavy metals “freshly” applied to the soil was visible only on light soil, additionally fertilized with NPK. Plants cultivated on soils with higher content of these metals usually accumulated at least several times higher amounts of zinc, both in their shoots and roots. Additional NPK fertilization often increased Zn content. The largest amounts of zinc were absorbed by plants from light soils freshly and permanently polluted with heavy metals, on which additional mineral (NPK) fertilization was applied, and next from medium soil, freshly polluted with heavy metals and fertilized with NPK.

Toxic Effects of Heavy Metals on the Growth and Phosphorus Removal Efficiency of Phosphorus Accumulating Microorganisms (PAOs)

Phosphorus accumulating microorganisms (PAOs) are influenced by various environmental factors and heavy metals. This study was performed to evaluate the effects of the selected heavy metals on the growth and phosphorus removal capacity of Bacillus sp. 3434 BRRJ, Pseudomonas aerunogisa, and Bacillus Subtilis, well known as PAOs. The heavy metals used in this study included Cu, Cd, As, and Zn. The <TEX>$IC_{50}$</TEX> (median inhibition concentration) values of Bacillus sp. 3434 BRRJ for the Cu, Cd, As, and Zn were 8.07 mg <TEX>$L^{-1}$</TEX>, 0.18 mg <TEX>$L^{-1}$</TEX>, 73.62 mg <TEX>$L^{-1}$</TEX> and 0.25 mg <TEX>$L^{-1}$</TEX>, respectively. The <TEX>$IC_{50}$</TEX> values of Pseudomonas aerunogisa for the Cu, Cd, As, and Zn were 4.45 mg <TEX>$L^{-1}$</TEX>, 0.16 mg <TEX>$L^{-1}$</TEX>, 18.51 mg <TEX>$L^{-1}$</TEX> and 2.34 mg <TEX>$L^{-1}$</TEX>, respectively. The <TEX>$IC_{50}$</TEX> values of Bacillus Subtilis for the Cu, Cd, As, and Zn were 3.81 mg <TEX>$L^{-1}$</TEX>, 0.18 mg <TEX>$L^{-1}$</TEX>, 11.31 mg <TEX>$L^{-1}$</TEX> and 0.47 mg <TEX>$L^{-1}$</TEX>, respectively. The phosphorus removal efficiencies of the three bacteria, Bacillus sp. 3434 BRRJ, Pseudomonas aerunogisa, and Bacillus subtilis were 93.12%, 71.81%, and 65.31%, respectively. Based on the results of the three PAOs obtained from the study, it appears that Bacillus sp. 3434BRRJ may have the best results in terms of their growth rate and P removal efficiencies.

Contribution of arbuscular mycorrhizal fungi to the development of maize (Zea mays L.) grown in three types of coal mine spoils

Coal mine spoils are usually unfavorable for plant growth and have different properties according to dumping years, weathering degree, and the occurrence of spontaneous combustion. The establishment of plant cover in mine spoils can be facilitated by arbuscular mycorrhizal fungi (AMF). A greenhouse pot experiment was conducted to evaluate the importance of AMF in plant adaptation to different mine spoils and the potential role of AMF for revegetation practices. We investigated the effects of Glomus aggregatum, Rhizophagus intraradices (syn. Glomus intraradices), and Funneliformis mosseae (syn. Glomus mosseae) on the growth, nutritional status, and metal uptake of maize (Zea mays L.) grown in recent discharged (S1), weathered (S2), and spontaneous combusted (S3) coal mine spoils. Symbiotic associations were successfully established between AMF and maize in three substrates. Mycorrhizal colonization effectively promoted plant growth by significantly increasing the uptake of nitrogen (N), phosphorus (P), and potassium (K), adjusting C:N:P stoichiometry and alleviating toxic effects of heavy metals. G. aggregatum, R. intraradices, and F. mosseae exhibited different mycorrhizal effects in response to mine spoil types. F. mosseae was the most effective in the development of maize in S1 and may be the most appropriate for revegetation of this substrate, while R. intraradices played the most beneficial role in S2 and S3. Our results suggest that inoculation with AMF can enhance plant adaptation to different types of coal mine spoils and play a positive role in the revegetation of coal mine spoil banks.

Variation in prevalence and intensity of two avian ectoparasites in a polluted area

We counted the numbers of pupae of two ectoparasitic flies (Protocalliphora sp. and Ornithomyia sp.) in the nests of a passerine bird, the pied flycatcher (Ficedula hypoleuca) to find out if their prevalence or intensity are affected by long-term environmental pollution by a copper smelter and whether such an interaction would have impacts on birds' breeding success. Fecal metal concentrations of F. hypoleuca nestlings were used to explore direct association between metal levels and parasite prevalence, but we also included other explanatory factors in our analysis, such as timing of breeding, brood size, ambient temperature, habitat quality and host population density. We found that environmental pollution decreased the prevalence of Protocalliphora via changed habitat quality but did not affect the prevalence of Ornithomyia. The prevalence of neither ectoparasite was, however, directly related to ambient metal levels. Both ectoparasites showed higher prevalence when ambient temperature during the nestling period was high, emphasizing the potential of climate change to modify host–parasite relationships. The prevalence of Ornithomyia was further highest in dense F. hypoleuca populations and late broods. Nestling survival decreased with increasing infestation intensity of Ornithomyia while no association was found for Protocalliphora. Despite relatively low numbers and overall weak effect of parasites on survival, the possible delayed and/or sublethal effects of these ectoparasites call for further studies. Our results suggest that pollution-related effects on avian ectoparasite numbers are species-specific and reflect habitat changes rather than direct toxic effect of heavy metals.

Toxicity and profitability of rice cultivation under wastewater irrigation: the case of the East Calcutta Wetlands

The paper reports the results of an empirical study on profitability of rice cultivation in the East Calcutta Wetlands (ECW) region where untreated sewage from the city of Kolkata (earlier Calcutta), India, is used for the purpose of irrigation during the winter/summer crop. The results show that plots using wastewater containing organic nutrients earn lower profits than those using groundwater. We also find that the profitability of plots using wastewater is negatively affected by the presence of heavy metals such as Lead and Mercury that are carried through untreated sewage-water canals and deposited in the soil. Of the two opposing effects of wastewater irrigation, the negative effect of heavy metal toxicity outweighs the positive effects of organic nutrients. The results support regulation of the discharge of the heavy metals like Lead and Mercury into the wastewater from households and industries. This would lead to conservation of the Wetlands generating a number of ecological and environmental benefits to the society.

Microbial community structure and functioning along metal pollution gradients

Toxic effects of heavy metals on soil microorganisms have been confirmed in a number of laboratory studies. However, most real-field studies do not allow for strong general conclusions due to a range of problems, such as pseudoreplication and confounding factors, which are almost impossible to control for with the most commonly used polluted versus unpolluted or random sampling designs. Effects of metal contamination on soil microbial community traits were measured along 2 pollution gradients in southern Poland. Employing an experimental regression design, using 2 separate gradients, the authors aimed to control for effects of soil properties and beta-diversity of microbial communities. General microbial activity was measured as soil basal respiration rate and substrate-induced respiration, while microbial functional and structural diversity were analyzed with community-level physiological profiles and phospholipid fatty acid patterns, respectively. Metal concentrations were normalized to their toxicity and integrated in a toxicity index (TI). Microbial activity (basal and substrate-induced respiration) decreased in both gradients with increasing TI. Community-level physiological profiles for fungi correlated positively with TI, but no impact of TI on the community-level physiological profiles of bacteria was observed. The phospholipid fatty acids a:15 and i:17 were positively correlated with TI, whereas 16:1ω9 and 18:2ω9 were negatively correlated with TI. The use of 2 gradients (Olkusz and Miasteczko Śląskie) allowed the authors to reveal a clear effect of pollution on general microbial structure and activities, even though they were not able to control completely for all confounding factors. Soil pH, organic matter content, and nutrient level appeared to be at least as important as TI in determining microbial community structure and activities.

Metal pollution assessment and multivariate analysis in sediment of Anzali international wetland

Anzali international wetland located in southwestern Caspian Sea coast is one of the most important wetlands of Iran from environmental and ecological points of view. Metal concentrations (Cu, Zn, Cr, Fe, Mn, Pb, Ni, Cd, and Li) in 41 surface sediment samples from Anzali wetland were determined. Assessment of ecological risk of sediment samples as well as their degree of contamination revealed considerable ecological risk and moderate degree of contamination in eastern part of the study area. Multivariate statistical analyses were used to identify metal content relationship and their origin. Higher enrichment factors of Cd, Pb, and Zn exhibited probable effects on human activities. Based on sediment quality guidelines (SQGs), moderate potential toxicity levels of sediment samples were identified. A new sediment quality index named sediment toxicity degree was developed based on the results of the multivariate statistical analysis to assess metal toxicity in surface sediments of aquatic systems. Results showed higher sensitivity of the new index (STd) to assess toxic effect of heavy metals on sediments and better capability to differentiate zones with different levels of risk within the study area than that of some other indices such as SQG-Q.

Effects of heavy metals as stress factors on anaerobic digestion processes and biogas production from biomass

Heavy metals affect the biochemical reactions that take place during anaerobic digestion processes of organic matter. In this review, the different effects observed in anaerobic digestion processes and during the production of biomethane and biohydrogen from several substrates contaminated with and/or inheriting heavy metals from the substrates themselves were discussed. It has been found that heavy metals exert important roles in biochemical reactions. Heavy metals like copper, nickel, zinc, cadmium, chromium and lead have been overwhelmingly reported to be inhibitory and under certain conditions toxic in biochemical reactions depending on their concentrations. Heavy metals like iron may also exhibit stimulatory effects, but these effects have been scantily observed. This review also concludes that the severity of heavy metal inhibition depends upon factors like metal concentration in a soluble, ionic form in the solution, type of metal species, and amount and distribution of biomass in the digester or chain of biochemical reactions which constitute the anaerobic digestion process. A majority of studies have demonstrated that the toxic effect of heavy metals like chromium, cadmium and nickel is attributable to a disruption of enzyme function and structure by binding of the metal ions with thiol and other groups on protein molecules or by replacing naturally occurring metals in enzyme prosthetic groups. This review has not found published data on the effects of heavy metals on the hydrolysis stage of anaerobic digestion process chemistry, and hence further studies are required to depict any changes.

Lead tolerance in plants: strategies for phytoremediation

Lead (Pb) is naturally occurring element whose distribution in the environment occurs because of its extensive use in paints, petrol, explosives, sludge, and industrial wastes. In plants, Pb uptake and translocation occurs, causing toxic effects resulting in decrease of biomass production. Commonly plants may prevent the toxic effect of heavy metals by induction of various celular mechanisms such as adsorption to the cell wall, compartmentation in vacuoles, enhancement of the active efflux, or induction of higher levels of metal chelates like a protein complex (metallothioneins and phytochelatins), organic (citrates), and inorganic (sulphides) complexes. Phyotochelains (PC) are synthesized from glutathione (GSH) and such synthesis is due to transpeptidation of γ-glutamyl cysteinyl dipeptides from GSH by the action of a constitutively present enzyme, PC synthase. Phytochelatin binds to Pb ions leading to sequestration of Pb ions in plants and thus serves as an important component of the detoxification mechanism in plants. At cellular level, Pb induces accumulation of reactive oxygen species (ROS), as a result of imbalanced ROS production and ROS scavenging processes by imposing oxidative stress. ROS include superoxide radical (O2(.-)), hydrogen peroxide (H2O2) and hydroxyl radical ((·)OH), which are necessary for the correct functioning of plants; however, in excess they caused damage to biomolecules, such as membrane lipids, proteins, and nucleic acids among others. To limit the detrimental impact of Pb, efficient strategies like phytoremediation are required. In this review, it will discuss recent advancement and potential application of plants for lead removal from the environment.

Biosorption of lead using pretreated cells of Aspergillus species

Microbial bioremediation is an emerging technology for environmental cleanup. Application of living biomass for metal binding depends on nutrient type and concentration, environmental conditions and cell age. In addition, living biomass may be subject to toxic effect of heavy metals at elevated concentrations. To overcome the disadvantages; non-viable or dead biomass is preferred. To test these hypothesis three fungal strains were isolated from effluent of chemical and pharmaceutical industry using SDA agar. Identification of the above isolates was carried out and was identified to be predominant strains of Aspergillus i.e. (Aspergillus niger and Aspergillus flavus). Further preliminary test was performed to check the tolerance of the fungi to different metal salts of lead, copper, chromium, zinc, nickel, cadmium using 1mM concentration. All three fungal species showed tolerance to metal salts like lead nitrate, zinc sulphate and cupric sulphate above 20 mM. Furthermore minimum inhibitory concentration was determined against the two above species for the three heavy metals. Pretreatment of live cells of Aspergillus strain was carried out .This dried biomass was then used for optimization of various parameters like concentration of metals, biomass concentration, pH, temperature of incubation and contact time. The filtrate was then analyzed after proper digestion and dilution by Atomic Absorption Spectrophotometer. The availability of variety of biomass and their metal binding potential makes it economical and sustainable option for developing effluent treatment process for removal and recovery of heavy metals.

Functioning of divalent alkaline metal on yeast multiplication in heavy metal contaminated soil

Microbial parameters appear to be very useful in monitoring soil contamination by heavy metals. The toxic heavy metals cause serious threat to the environment, Nowadays, the most an important ecological problem is to correct the toxic effect of heavy metals in contaminated soils. In vitro, two strains of Saccharomy ces cerevisiae (NSS5099 and NSS7002) were tested in order to investigate their tolerance to heavy metals. The growth kinetics of two yeast strains in contaminated growth media by Cu2+, Pb2+, Cd2+ and Ni2+ were studied at 50 µM. The toxicity decreasing order of the investigated heavy metal salts on tested yeast strains was found to be Cu2+ &gt; Pb2+ &gt; Cd2+ &gt; Ni2+. Ions of Cu2+, Pb2+ and Cd2+ at 350 µM and Ni2+ at 450 µM induced a decrease in the number of viable cells by 50% after 48 h incubation at 25°C. The addition of 50 mM Ca(HCO3)2, 75 mM MgSO , or 150 mM K SO in the growth broth medium before addition of 350 µM Cu2+, Pb2+ and Cd2+ or 450 µM Ni2+ shows a protective action against cell death and decreased the toxicity effect. The addition of alkaline metals reduced the effect of 350 and 450 µM of all investigated metals by 40%. The results obtained in the presented study exhibit the higher potentiality of S. cerevisiae strain NSS7002 than the strain NSS5099 to be used for decontamination of soil containing heavy metal ions. Further task is going to examine the range of metal bioaccumulation in the yeast cells and the ability of these strains to be environmental bioremediators.