• Journal of Microbiology and Biotechnology
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• v.18 no.7
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• pp.1298-1307
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• 2008

In this study, we investigated the inhibition effects of single and mixed heavy metal ions ($Zn^{2+},\;Ni^{2+},\;Cu^{2+},\;and\;Cd^{2+}$) on iron oxidation by Acidithiobacillus ferrooxidans. Effects of metals on the iron oxidation activity of A. ferrooxidans are categorized into four types of patterns according to its oxidation behavior. The results indicated that the inhibition effects of the metals on the iron oxidation activity were noncompetitive inhibitions. We proposed a reduced inhibition model, along with the reduced inhibition constant ($\alpha_i$), which was derived from the inhibition constant ($K_I$) of individual metals and represented the tolerance of a given inhibitor relative to that of a reference inhibitor. This model was used to evaluate the toxicity effect (inhibition effect) of metals on the iron oxidation activity of A. ferrooxidans. The model revealed that the iron oxidation behavior of the metals, regardless of metal systems (single, binary, ternary, or quaternary), is closely matched to that of any reference inhibitor at the same reduced inhibition concentration, $[I]_{reduced}$, which defines the ratio of the inhibitor concentration to the reduced inhibition constant. The model demonstrated that single metal systems and mixed metal systems with the same reduced inhibitor concentrations have similar toxic effects on microbial activity.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.35-47
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• 1999

Mine tailings, soils. stream sediments around Gubong disused mine were analyzed in order to investigate their distribution and pollution levels of heavy metals and cyanide. The average contents of As, Cd, Cu. Hg, Pb, Zn, and CN￣ in mine tailings were 6.93$\times$$10^{3}$, 56.9, 209, 5.03, 3.25$\times$$10^{3}$, 1.89$\times$$10^{3}$, 21mg/kg respectively. The pollution indices that calculated by the tolerance level of Kloke were 42~95 and the pH values were slightly alkaline in mine tailings. The contents of heavy metals and cyanide in field soils near the mine were higher than the paddy soils. The contents of heavy metals in the stream sediment were up to that of the tailings, so contamination from the mine tailings were serious.

• Korean Journal of Environmental Agriculture
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• v.33 no.3
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• pp.220-230
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• 2014

BACKGROUND: Excessive metals in the soil have become one of the most significant environmental problems. Phytoremediation has received considerable attention as a method for restoring the contaminated soils. The microbes having remarkable metal tolerance and plant growth-promoting abilities could also play a significant role in remediation of metal-contaminated soils, because bioaugmentation with such microbes could promote phytoextraction of metals. Therefore, the present study was focused on evaluating the phytoextraction of heavy metals (Co, Pb and Zn) in Helianthus annuus (sunflower) induced by bioaugmentation of a phosphate solubilizing bacterium. METHODS AND RESULTS: A phosphate solubilizing bacterium was isolated from metal-contaminated soils based on the greater halo size (>3 mm) with solid NBRIP agar medium containing 10 g glucose, 5 g $Ca_3(PO_4)_2$, 5 g $MgCl_2{\cdot}6H_2O$, 0.25 g $MgSO_4.7H_2O$, 0.2 g KCl, 0.1 g $(NH_4)_2SO_4$ in 1 L distilled water. Isolated bacterial strain was assessed for their resistance to heavy metals; $CoCl_2.6H_2O$, $2PbCO_3.Pb(OH)_2$, and $ZnCl_2$ at various concentrations ranging from $100-400{\mu}g/mL$ (Co, Pb and Zn) using the agar dilution method. A pot experiment was conducted with aqueous solutions of different heavy metals (Co, Pb and Zn) to assess the effect of bacterial strain on growth and metal uptake by Helianthus annuus (sunflower). The impact of bacterial inoculation on the mobility of metals in soil was investigated under laboratory conditions with 50 mL scaled polypropylene centrifuge tubes. The metal contents in the filtrate of plant extracts were determined using an atomic absorption spectrophotometer (Perkinelmer, Aanalyst 800, USA). CONCLUSION: Inoculation with Enterobacter ludwigii PSB 28 resulted in increased shoot and root biomass and enhanced accumulation of Co, Pb and Zn in Helianthus annuus plants. The strain was found to be capable of promoting metal translocation from the roots to the shoots of H. annuus. Therefore, Enterobacter ludwigii PSB 28 could be identified as an effective promoter of phytoextraction of Co, Pb and Zn from metal-contaminated soils.

• The Korean Journal of Ecology
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• v.27 no.1
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• pp.15-20
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• 2004

With attention to different human activities around Anzali wetland and introduction of different pollutants containing heavy metals into this water ecosystem and absorption and accumulation of heavy metals in shell and muscle of Astacus leptodactylus which is native benthose of Anzali wetland and enjoys food and economic importance; Sampling of waters and sediments from 18 stations and shell and muscle of Astacus leptodactylus from 5 stations had been conducted. After biometric evaluation of Astacus leptodactylus, the chemical analysis of the samples by using international and standard methods and then their heavy metals content was determined by Atomic Absorpotion Spectrophotometer (AAS), model P.U 9400 philips. Result of the analysis stated that; 1) The mean values of Cr, Zn, Pb, Ni, V in Anzali waters were 6.4, 184.5, 28.8, 28.9, 47.1 ($\mu$ gr/lit) respectively, which comparing to the international standards, is not suitable for drinking, but it can be used for agricultural and aquacultural purposes. Even though the concentration of heavy metals in sediments were high, there are in range of acceptable limit for aquatics organisms; 2) Comparatively, the concentration of heavy metals in shell and muscle of Astacus leptodactylus in Anzali wetland (Cr, Zn, Pb, Ni, V in shell were 3.48, 109.3, 14.13, 7.17, 36.2 and in muscle were 2.98, 131.98, 3.12, 4.77, 9.05 ppm respectively) were more than what is determined for Aras dam (in shell were 1.6, 224.3, 7.8, 7.6, 10.3 and in muscle were 1.4, 60.2, 0.45, 2.7, 4.4 mg/kgr respectively); 3) For all samples, concentration of heavy metals in all Astacus leptodactylus in Anzali wetland and Aras dam, was at tolerance level for human consumption; 4) There was no association with significant difference between weight and size of Astacus leptodactylus with absorption and accumulation of heavy metals; but there was a significant association between heavy metals content in water and in sediments, and in sediments, shell and muscle of Astacus leptodactylus in Anzali wetland.

• Journal of Korea Soil Environment Society
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• v.3 no.3
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• pp.33-44
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• 1998

Mine tailings, soils, stream sediments, and ground water around Imcheon disused mine were analyzed in order to investigate their pollution levels of heavy metals and cyanide. The average contents of As, Cd, Cu, Hg, Pb, Zn, and CN￣ in mine tailings were 366, 28.8, 202, 15.2, 1.97$\times$$10^3$, 3.85$\times$$10^3$, 90.6mg/kg respectively, The pollution indices that calculated by the tolerance level of Kloke were 8~19 and the pH values were acidic in mine tailngs. In the field and paddy soils of Imcheon disused mine area except for soils nearby mine tailngs, concentraitons of the heavy metals were less than standards of soil pollution of agricultral area in the environmental protection law. The nitrate contents In the ground water for drink were more than tolerance level of the drinking water of Ministry of Health and Social Affairs.

• Journal of Food Hygiene and Safety
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• v.16 no.4
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• pp.324-332
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• 2001

Foods constitute a large portion of heavy metal exposure toward general population and attract a deep concern with respect to assuring human health. This study summarized published data in Korea on the content, and dietary intake of heavy metals and assessed their risk potential in comparison with foreign data. An analysis for the yearly fluctuation of metal contents including arsenic, cadmium, mercury and lead by flood group (marine fishes, coastal shellfishes, freshwater fishes, cereal grains) exhibited a decreasing trend from the 1970s to the 1990s. When compared with domestic standards of heavy metals, their mean contents were below the limit and their maximum values seldom exceeded the limit. The data on the dietary intake of heavy metals by Koreans showed a decreasing trend from the 1980s to the 1990s. The average intakes offs and Hg were 6∼8% and those of Cd and Pb were 50∼80% of PTWI(provisional tolerable weekly intake), all of which were below the tolerance. As the extreme intakes of these metals may exceed the PTWI, a careful assessment for them may be necessary. Dietary intakes of Cd, Hg and Pb by Koreans lie in the mid-level among countries cited in the GEMS/Food monitoring data. As fishery foods are suspecious of contamination with Hg, Cd and As, and floods in general are with Pb, it is necessary to establish legal limits for these metals and monitor any progress of their contamination. Furthermore, overall assessment of exposure to heavy metals from all sources including floods, air, drinking water and occupation should be made in order to confirm the dietary risk factors and to assure the safety of food resources.

• Microbiology and Biotechnology Letters
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• v.26 no.1
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• pp.83-88
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• 1998

Heavy metal removal by Z. ramigera 115 and soluble slime polymer producing mutant Z. ramigera 115SLR was investigated. Both strains showed similar tolerance against $Cd^{2+}$, $Co^{2+}$, $Cu^{2+}$, $Ni^{2+}$ and $Fe^{2+}$. When cells were cultivated in the presence of 500 ppm $Cd^{2+}$, the mutant strain removed 1.5 fold more metal than the wild type did at same biomass. Metal adsorption capacities were in the order of Z. ramigera l15SLR polymer > Z. ramigera 115 polymer > Z. ramigera 115 cell >Z. ramigera l15SLR cell. The optimum pH for metal adsorption was 7.5. Langmuir and Freundlich isotherms indicated that Qmax and 1/n of Z. ramigera l15SLR polymer were 164.2 mg $Cd^{2+}$/g dw and 0.496, respectively. These results showed that the polymer of Z. ramigera l15SLR could be used as an effective metal adsorbate.

• Journal of Korea Soil Environment Society
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• v.4 no.2
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• pp.175-183
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• 1999

Mine tailings, field soils, and paddy soils around Jingok abandoned mine were analyzed In order to investigate their pollution levels of heavy metals and cyanide. The average contents of As, Cd, Cu. Hg. Pb, Zn, and CN￣in mine tailings were 3.94$\times$$10^3$, 14.3, 266, 6.13, 4.07$\times$$10^3$, 2.51$\times$$10^3$, and 1.19mg/kg, respectively. The pollution indices calculated by the tolerance level of Kloke were 32~58 and the pH values were slightly acidic in mine tailings. In the field and paddy soils of Jingok abandoned mine area except for soils nearby mine tailings, concentrations of the heavy metals were less than standards of soil pollution of agricultural area in the environmental protection law.

• Microbiology and Biotechnology Letters
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• v.32 no.4
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• pp.341-346
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• 2004

The quantification of the toxicological effects of the heavy metals such as Cu, Cd, Cr, Hg, and Zn on the growth of Escherichia coli was performed, and the variations of toxicwith exposure time were evaluated in adaptation procedure. The characteristics of growth inhibition on Escherichia coli by heavy metals were different with metal species, and critical concentration of each metal, which inhibited cell growth completely, were Cu of 3.5 mM, Zn of 2.5 mM, Cd of 1.5 mM, Cr of 1.2 mM, and Hg of 0.12 mM, respectively. The tolerance of E. coli against heavy metals, based on $EC_{50}$ values, increased in order of Cu > Zn > Cr > Cd > Hg. The slopes obtained from the relationship between ECso values and expose time corresponds to adaptability of test organisms to the toxicants. The adaptability of test organisms to the toxicants was much higher at higher slope values. Adaptability of E. coli on heavy metals increased in order to Zn > Cd > CU >> Cr> Hg.

• Korean Journal of Environmental Biology
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• v.20 no.4
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• pp.360-365
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• 2002

The variety and density of entomopathogenic nematodes from the polluted soils of heavy metals were examined. In order to investigate the pollution of heavy metals in soil, 300 sites in kyungsangbuk-do were collected from March to October in 2001. We measured the contents of seven heavy metal elements (Cd, Cu, As, Hg, Pb, Cr^{6+}$, CN) and than cheesed soil of 25 sites with high concentration of heavy metals. The seven strains of nematodes were isolated from seven samples by silkworm host (Bombyx mori mori) and white trap. Isolated nematodes are composed of two families, one order. The members of Rhabditida were isolated in the soil with mean Cd content of 0.870 ppm. And they were isolated in the soil samples with As content less than 0.745 ppm. However they were isolated regardless of concentration of Cu and Pb. The members of Cylindrocorpidae were isolated in the soil samples with Cr^{6+}$ content less than 0.05 ppm. Any entomopathogenic nematode was not detected in the CN polluted soil. Isolated nematodes successfully cultured on the silkworm host and were confirmed the pathogenicity, multiplicity, and tolerance against various condition of preservation. Which proved its potential usefulness as biological agent.