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PubMed1983

In vitro susceptibility of spiroplasmas to heavy-metal salts.

The susceptibility of six spiroplasma strains to heavy-metal salt was characterized in terms of minimal inhibitory concentrations and minimal biocidal concentrations in broth tube dilution tests. The strains were most susceptible to mercuric chloride and silver nitrate; less susceptible to copper sulfate, cobalt chloride, lead nitrate, and cadmium sulfate; and least susceptible to nickel chloride and zinc sulfate. Spiroplasma citri strains Maroc R8A2 and C189 were the most susceptible to five of eight heavy-metal salts, and honeybee spiroplasma strain AS576 and Spiroplasma floricola strain 23-6 were generally the least susceptible. The difference between the minimal biocidal concentrations and the minimal inhibitory concentrations was greater for certain heavy-metal salts than for others.

Hydrogen-Ion Concentration↗

PubMed2006

Acinetobacter bioreporter assessing heavy metals toxicity.

This work was conducted to employ a whole cell-based biosensor to monitor toxicity of heavy metals in water and wastewater. An isolate of industrial wastewater bacterium, Acinetobacter sp. DF4, was genetically modified with lux reporter gene to create a novel bioluminescent bacterial strain, designated as DF4/PUTK2. This bioreporter can investigate the toxicity through light inhibition due to cell death or metabolic burden and the specific stress effects of the tested soluble materials simultaneously. The use of Acinetobacter DF4/PUTK2 as a bioluminescent reporter for heavy metal toxicity testing and for the application of wastewater treatment influent toxicity screening is presented in this study. Among eight heavy metals tested, the bioluminescence of DF4/PUTK2 was most sensitive to Zn, Cd, Fe, Co, Cr followed by Cu in order of decreasing sensitivity. The same pattern of sensitivity was observed when several contaminated water and wastewater effluents were assayed. This work suggested that luxCDABE -marked Acinetobacter bacterium DF4/PUTK2 can be used to bioassay the ecotoxicity of wastewater and effluent samples contaminated with heavy metals. Using this assay, it is possible to pre-select the more toxic samples for further chemical analysis and to discard wastewater samples with low or no inhibition because they are not toxic to the environment.

Acinetobacter↗

PubMed1977

Production of copper coproporphyrin III by Bacillus cereus. II. Regulation of the biosynthesis of coproporphyrin III and its copper complex by oxygen and heavy metal ions.

The effects of oxygen and heavy metal ions on the production of copper coproporphyrin III were studied in Bacillus cereus strain 2. The formation of copper coproporphyrin III was found to be maximum when the cells were cultivated in G-medium at a low level of oxygen supply, but it was suppressed at extremely low oxygen supply levels. When the cells were cultured in metal-free G-medium, neither metal-coproporphyrin III nor coproporphyrin III was formed. In the presence of copper in the medium (400-100 micrometers), the formation of coproporphyrin III copper salt was maximum, but the addition of various heavy metal ions other than copper to the copper-free medium resulted in the formation of neither coproporphyrin III nor its metal chelates. Copper ions appear to be specifically required for coproporphyrin III formation.

Bacillus cereus↗

PubMed2002

[Toxicity assessment of soil contaminated by heavy metals using algae growth inhibition test].

Scenedesmus obliquus growth inhibition test was carried out to assess the toxicity of soil contaminated by heavy metals. The results showed that the growth rate of Scenedesmus obliquus was positively related to the concentration of heavy metals added to soil, and it was decreased with the increasing concentration of heavy metals. Two parameters were chosen and the sensitivities were compared. It was found that the cell growth rate was more sensitive than OD growth rate. The orders of general detection limit by EC50 of different metals were Pb > Cu > Zn > Cd by using cell growth rate as the test index and Pb > Cu > Cd > Zn by using OD as the test index. This study also indicated that under the complex pollution condition, the toxicity of heavy metals in soil was stronger than that in the case of soil contaminated by single metal.

Cadmium↗

PubMed1998

Heavy metals in green mussels (Perna viridis) from the Gulf of Thailand.

Concentrations of seven heavy metals were determined in green mussels (Perna viridis) collected between April and June 1995 from eight locations along the costal area of the Gulf of Thailand. The average concentrations (n = 96) of the heavy metals detected in mussel samples, on the basis of dry weight, were 1.20 mg kg-1 cadmium, 0.78 mg kg-1 for chromium, 9.85 mg kg-1 for copper, 1.09 mg kg-1 for lead 2.78 mg kg-1 for manganese, 1.54 mg kg-1 for nickel, and 94,48 mg kg-1 for zinc. The levels of cadmium, chromium, nickel, and lead found in green mussels from four locations in the Upper Gulf were significantly (P < 0.05) higher than those detected in mussels from four locations in the Lower Gulf, while the levels of copper, manganese, and zinc did not differ significantly (P > 0.05) between the Upper and Lower Gulf. Comparison with earlier studies revealed that the concentrations of some metals in the mussels collected from the Upper Gulf are increasing. The concentrations of heavy metals in green mussels from the Gulf of Thailand were within acceptable levels for human consumption.

Animals↗

PubMed2006

[Evaluation of heavy metals bioavailability and mobility in polluted soils: A comparison of four methods].

The accumulation of heavy metals in soil could give impact to the environment, and the impact is related to the accumulated heavy metals' bioavailability and mobility. This paper studied the feasibility of four methods, i. e., total analysis, sequential fractionation, chemical extraction, and column leaching, in evaluating the bioavailability and mobility, and the results showed that because of the difference in chemical forms of the metals in different soils, the total concentration of the metals in soil was not suitable to evaluate their bioavailability and mobility. Exchangeable forms of the metals obtained by chemical fractionation could better reflect, while the organic matter-bound forms of some metals had definite correlation with the bioavailability and mobility. There were no significant correlations between the oxides-bound and residual metals and the bioavailability and mobility. Column leaching was also feasible to evaluate the bioavailability and mobility. 0.01 mol x L(-1) CaCl2 and 1 mol x L(-1) NH4OAc extractable metals were significantly correlated with the metals concentrations in surface runoff and plant, and could better predict the potential runoff of heavy metals from soil and the accumulation of the metals in plants.

Biological Availability↗

PubMed2006

Structural diversity of bacterial communities in a heavy metal mineralized granite outcrop.

This laboratory study of a variably mineralized and hydrothermally altered granite outcrop investigated the influences of rock-surface chemistry and heavy metal content on resident bacterial populations. Results indicated that elevated heavy metal concentrations had a profound impact on bacterial community structure, with strong relationships found between certain ribotypes and particular chemical/heavy metal elements. Automated ribosomal intergenic sequence analysis (ARISA) was used to assess the nature and extent of bacterial diversity, and this was combined with chemical analysis and multivariate statistics to identify the main geochemical factors influencing bacterial community structure. A randomization test revealed significant changes in bacterial structure between samples, while canonical correspondence analysis (CCA) related each individual ARISA profile to linear combinations of the chemical variables (mineralogy, major element and heavy metal concentrations) revealing the geochemical factors that correlated with changes in the ARISA data. anova was performed to further explore interactions between individual ribotypes and chemical/heavy metal composition, and revealed that a high proportion of ribotypes correlated significantly with heavy metals.

Bacteria↗

PubMed1987

Reversible inhibition of acetylcholine contracture of molluscan smooth muscle by heavy metals: correlation to Ca++ and metal content.

The present study examined the effects of three heavy metals on the acetylcholine (ACh) contracture and Ca++ kinetics of the anterior byssus retractor muscle of Mytilus edulis. An isolated tissue bioassay using anterior byssus retractor muscle was prepared according to standard procedures and the isometric tension produced in response to ACh was measured. Ten millimolar Ni++, Co++ or Cd++ reduced the maximum contracture response to ACh in zero-Ca medium in a time-dependent manner. The inhibition was reversed upon restoration of medium containing 10 mM Ca++. The loss (and re-establishment) of contracture response to ACh corresponded to the influx (and efflux) of the heavy metal ions opposite to the direction of Ca++ flow. These results are consistent with the concept that the loss of the ACh contracture response is attributable to the displacement of tissue Ca++ from release sites by heavy metals.

Acetylcholine↗

PubMedDate not supplied

[Bacterial cell membrane ATPase in assessing heavy metal toxicity].

Sensitivity of membrane ATPase to heavy metals was studied in bacterial stains Bacillus cereus ATCC 14579, Bacillus cereus B4368, and Alcaligenes eutrophus CH34 was studied. The inhibition effects of metals on membrane ATPase ranged in the same order (Au > Cu > Zn > Co > Mn) as their effects on the growth of cultures. It is suggested that membrane ATPase is one of the targets for the action of heavy metal ions within the microbial cell and, therefore, its activity may serve as an indicator of their toxicity.

Adenosine Triphosphatases↗

PubMed2002

Relation between growth and the heavy metal concentration in organs of bream Abramis brama L. populating Lake Balaton.

The effect of growth and physical condition on the level of heavy metals accumulated in the organs of common bream (Abramis brama L.) populating Lake Balaton was investigated on samples collected in October 1999 and May 2000 from two well-separable sites regarding their trophic state and pollution impact (western and eastern basins). The average metal concentrations in the organs of fish varied in the following ranges: Cd, 0.39-1.98; Cu, 1.73-57.3; Hg, 0.02-0.13; Pb, 0.39-3.15; and Zn, 12.7-159.3 microg/g dry weight. The highest Cd, Cu, Pb and Zn concentrations were detected in the gill and liver of fish, whereas the highest Hg concentrations were measured in the muscle. The maximum metal concentrations in the muscle of bream were on average below the maximum permissible levels for human consumption. Significant positive correlation was found among the heavy metal load of bream and their instantaneous growth rate; hardly any connection was observed related to the physical condition of samples. The relatively low metal concentrations of the ambient water and their poor correlation with the heavy metal load of bream, indicates that for the mature stages of this fish species the metal uptake from food is predominant, and thus the heavy metal load of fish reflect more the pollution state of the sediment and its biota, rather than that of the ambient water.

Animals↗

PubMed2004

Aquatic snails from mining sites have evolved to detect and avoid heavy metals.

Toxicants in polluted environments are often patchily distributed. Hence, rather than being passive absorbers of pollution, some organisms have evolved the ability to detect and avoid toxicants. We studied the avoidance behavior of Physella columbiana, an aquatic pulmonate snail, in a pond that has been polluted with heavy metals for more than 120 years. Populations of this snail are rare at reference sites and are only robust at heavy-metal-polluted sites. We hypothesized that the snails are able to persist because they have evolved the ability to minimize their exposure to metals by actively avoiding metals in their environment. Using a Y-maze flow tank, we tested the avoidance behavior of snails to heavy-metal-polluted sediments and single-metal solutions of cadmium, zinc, or lead. We also tested the avoidance behaviors of the snails' laboratory-reared offspring raised in nonpolluted conditions. In addition, we tested the avoidance behavior of a small population of snails from a reference pond. Although all the snails we tested were able to detect low concentrations of heavy metals, we found that snails from the polluted site were the most sensitive, that their offspring were somewhat less sensitive, and that snails from the reference site were the least sensitive. This suggests that the ability of polluted-site snails to avoid heavy metals is both genetic and environmental. The concentrations of metals avoided by the snails from the polluted site were below the levels found at hot spots within their natal pond. The snails may be able to persist at this site because they decrease their exposure by moving to less-polluted sections of the pond. One application of our findings is the use of aquatic snails and our Y-maze design as an inexpensive pollution detector. Environmental pollutants such as lead, zinc, and arsenic are a problem throughout the world. People in underdeveloped countries often lack sophisticated pollution detection devices. We have developed a behavioral assay of aquatic pollution that is easy to use, is extremely sensitive (detection below 10 ppb), and can be constructed for fewer than 100 US dollars. Pulmonate snails are widely distributed in tropical, subtropical, and temperate parts of the globe, and they are often common in polluted waters. For countries such as India and Bangladesh, which must test thousands of shallow wells for possible contamination with heavy metals, our assay would be a good initial test. Once snails detected metals, then those samples could be confirmed by spectrometers. We encourage scientists in underdeveloped nations to consider our assay as an option.

Animals↗

PubMed1985

N-Acetylcysteine therapy of acute heavy metal poisoning in mice.

Therapy of acute heavy metal poisoning is currently limited to a group of moderately toxic drugs containing sulfhydryl groups. N-Acetylcysteine (NAC) was used in these studies to determine if this sulfhydryl containing amino acid would reduce the overall mortality of a group of heavy metal compounds. D-Penicillamine and dimercaprol (BAL) were also used for comparison. Groups of at least 100 mice (28 g) were injected subcutaneously with 2-190 mg/kg of copper, arsenic, thallium or cadmium for LD50 determinations. Other groups were injected 30-60 min later with NAC (200 mg/kg), d-penicillamine (50 mg/kg), or BAL (10 mg/kg), and mortality was monitored for 2 weeks. The LD50 for each treatment group was determined by regression analysis of log-probit transformed data. In arsenite treatment group the survival time was lengthened in NAC-treated animals although the LD50 was not significantly changed. BAL was only slightly more effective than NAC. The mortality in animals given copper and treated with NAC was almost eliminated, except at the highest doses. BAL provided the greatest protection, whereas d-penicillamine produced the least. The LD50 of copper was significantly changed from 60.5 mg/kg in control groups to 139 mg/kg in NAC-treated groups, and to 150 mg/kg and 91 mg/kg in BAL and d-penicillamine-treated groups. NAC and BAL were totally ineffective in the treatment of thallium and cadmium poisoning.

Acetylcysteine↗

PubMed2025

Partners in root nodule symbiosis respond uniquely to heavy metal stresses in a host genotype-dependent manner.

The mutualistic symbiosis between legume roots and soil rhizobia culminates in the formation of root nodules, where nitrogen is fixed. Root nodule symbiosis is inhibited by heavy metal stress. In this study, we investigated the relative responses of the symbiotic partners to a non-essential heavy metal cadmium (Cd) and an essential heavy metal zinc (Zn) stress and identified patterns in gene expression. We performed dual transcriptomics in nodules, using the Medicago truncatula-Sinorhizobium meliloti symbiotic system. Phenotypes were measured in the wild-type Medicago truncatula and a mutant in an ABC transporter gene (Mtabcg36), which showed compromised nodule formation in control conditions and further after heavy metal treatment. We observed that the rhizobia were particularly sensitive to Zn in mutant nodules. The greatest degree of differential gene expression in the host plant were observed under Cd and Zn treatments in wild-type nodules. Most Cd-regulated host genes were also differentially regulated by Zn, revealing little discernment between an essential and a non-essential ion under increased exposure. Furthermore, the host response to both the stresses affected auxin and iron homeostasis genes in a host genotype-dependent manner. Our results suggested impaired cadmium export from the mutant nodules. These results have potential implications in agricultural management systems and bioremediation strategies.

Symbiosis↗

PubMed2001

A preliminary model for predicting heavy metal contaminant loading from an urban catchment.

The toxicity of heavy metals to biota in urban catchments has been regarded as a very important non-point source pollution issue. Numerous studies on heavy metal pollution in urban receiving waters have found that metal transport by surface runoff is closely correlated to the partitioning of the metal forms between dissolved and particulate phases, where sediment plays an important role in the transport process. Sediment cycling on urban streets, metal binding form, and rainfall character in the catchment area are considered to be the key factors for metal transport. A preliminary model is developed based on these considerations. Starting from classical build-up and wash-off processes for the suspended sediment (SS) on the urban impervious surface, the model links the transport of suspended sediment to the transport of metal species. Monitoring data from a small highway catchment were used in the model development. A total of 47 rain events over 1 year were monitored intensively at short time intervals (5-10 min) for hydrological data, rainfall intensity, and stormwater quality. In developing the model, lead was used for the metal load prediction, as it has been a common fuel additive for urban transportation. Agreement between model results and monitoring data indicates that the model can be used in predicting metal load from impervious urban areas, such as streets and roadways, on a long-term basis.

Animals↗

PubMed1984

Bacterial transformations of and resistances to heavy metals.

Bacteria carry out chemical transformations of heavy metals. These transformations (including oxidation, reduction, methylation, and demethylation) are sometimes byproducts of normal metabolism and confer no known advantage upon the organism responsible. Sometimes, however, the transformations constitute a mechanism of resistance. Many species of bacteria have genes that control resistances to specific toxic heavy metals. These resistances often are determined by extrachromosomal DNA molecules (plasmids). The same mechanisms of resistance occur in bacteria from soil, water, industrial waste, and clinical sources. The mechanism of mercury and organomercurial resistance is the enzymatic detoxification of the mercurials into volatile species (methane, ethane, metallic HgO) which are rapidly lost from the environment. Cadmium and arsenate resistances are due to reduced net accumulation of these toxic materials. Efficient efflux pumps cause the rapid excretion of Cd2+ and AsO4(3-). The mechanisms of arsenite and of antimony resistance, usually found associated with arsenate resistance, are not known. Silver resistance is due to lowered affinity of the cells for Ag+, which can be complexed with extracellular halides, thiols, or organic compounds. Sensitivity is due to binding of Ag+ more effectively to cells than to Cl-.

Antimony↗

PubMed2004

Heavy metal content of ayurvedic herbal medicine products.

CONTEXT: Lead, mercury, and arsenic intoxication have been associated with the use of Ayurvedic herbal medicine product (HMPs). OBJECTIVES: To determine the prevalence and concentration of heavy metals in Ayurvedic HMPs manufactured in South Asia and sold in Boston-area stores and to compare estimated daily metal ingestion with regulatory standards. DESIGN AND SETTING: Systematic search strategy to identify all stores 20 miles or less from Boston City Hall that sold Ayurvedic HMPs from South Asia by searching online Yellow Pages using the categories markets, supermarkets, and convenience stores, and business names containing the word India, Indian cities, and Indian words. An online national directory of Indian grocery stores, a South Asian community business directory, and a newspaper were also searched. We visited each store and purchased all unique Ayurvedic HMPs between April 25 and October 24, 2003. MAIN OUTCOME MEASURES: Concentrations (microg/g) of lead, mercury, and arsenic in each HMP as measured by x-ray fluorescence spectroscopy. Estimates of daily metal ingestion for adults and children estimated using manufacturers' dosage recommendations with comparisons to US Pharmacopeia and US Environmental Protection Agency regulatory standards. RESULTS: A total of 14 (20%) of 70 HMPs (95% confidence interval, 11%-31%) contained heavy metals: lead (n = 13; median concentration, 40 microg/g; range, 5-37,000), mercury (n = 6; median concentration, 20,225 microg/g; range, 28-104,000), and/or arsenic (n = 6; median concentration, 430 microg/g; range, 37-8130). If taken as recommended by the manufacturers, each of these 14 could result in heavy metal intakes above published regulatory standards. CONCLUSIONS: One of 5 Ayurvedic HMPs produced in South Asia and available in Boston South Asian grocery stores contains potentially harmful levels of lead, mercury, and/or arsenic. Users of Ayurvedic medicine may be at risk for heavy metal toxicity, and testing of Ayurvedic HMPs for toxic heavy metals should be mandatory.

Arsenic↗

PubMed1999

Atmospheric heavy metal deposition plumes adjacent to a primary lead-zinc smelter.

A method for the determination of atmospheric heavy metal deposition rates has been developed using 0.5-m2 deposition trays at 0.1 m from the ground. Trays were spaced at 150-m intervals along a 1500-m line 500 m east of a Pb-Zn smelter. Ten sampling events of 1-3-h duration were conducted under westerly wind conditions so as to determine the sources of heavy metals deposited near the smelter. Deposited materials were sampled from the trays using wipes. There was good agreement between deposition trays placed side-by-side and exposed in pairs. Under certain conditions, however, the method is not appropriate owing to the potential for local contamination. Geometric mean deposition rates for Pb, Zn, Fe, Cu, As and Cd averaged over a nominal plume width of 600 m amounted to 18.8, 22.2, 12.2, 0.614, 0.403 and 0.052 mg m-2 day-1, respectively. Gaussian deposition profiles were seen for Pb, Zn, Fe, Cu, As and Cd downwind from the blast furnace, sinter plant, and refinery area. Zinc deposition could also be attributed to a northern Zn production area. This northern site was not generally associated with elevated Pb deposition. On the basis of this work, the deposition of heavy metals in residential areas adjoining the smelter is likely to occur downwind from the smelter site, with deposition rates increasing with wind speed. The strategic measurement of heavy metal dry-deposition rates over short periods of time using large collection surfaces provides source-specific information not obtainable by conventional long-term 'passive' deposition sampling. Lower detection limits than those achieved here are likely to be achieved in non-smelter settings. Previous suggestions implicating a sink of city surface dusts as the probable source of Pb recontamination of residential settings in the absence of ongoing smelter emissions are not supported by this work.

Air Pollutants↗

PubMed2006

Characterization of the proteins of bacterial strain isolated from contaminated site involved in heavy metal resistance--a proteomic approach.

The present study describes response of a bacterial strain isolated from a polluted river to heavy metal toxicity. The bacterium was identified to be Klebsiella pneumoniae by biochemical tests using API 20E strips and 16S ribotyping. The isolate was studied for its tolerance to two heavy metals, i.e., cobalt (Co(2+)) and lead (Pb(2+)) by growing it in citrate mineral medium (CMM). Proteomic approach involving two-dimensional polyacrylamide gel electrophoresis (2D PAGE) and mass spectrometry (MS) was used to identify the differentially expressed proteins under heavy metal stress. Two of the differentially expressed proteins were identified to be l-isoaspartate protein carboxymethyltransferase type II and DNA gyrase A. To our knowledge, this is for the first time that K. pneumoniae has been reported to be present in metal contaminated site and l-isoaspartate protein carboxymethyltransferase type II protein to be over expressed under heavy metal stress. The role of these proteins in metal tolerance is discussed.

Bacterial Proteins↗