• 한국환경과학회지
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• 제21권3호
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• pp.369-375
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• 2012

We investigated usefulness of chicken feather as bioadsorbent for removal of hexavalent chromium[Cr(VI)] and oil from aqueous solution. Chicken feather was chemically treated with DTPA, EDTA, NaOH and SDS, respectively. Among them, EDTA was the most effective in adsorbing Cr(VI). Cr(VI) uptake by chicken feather was increased with decreasing pH; the highest Cr(VI) uptake was observed at pH 2.0. By increasing Cr(VI) concentration, Cr(VI) uptake was increased, and maximum Cr(VI) uptake was 0.34 mmol/g. Cr(VI) adsorption by chicken feather was well described by Freundlich isotherm than Langmuir isotherm and Freundlich constant(1/n) was 0.476. As the concentration of chicken feather was increased, Cr (VI) removal efficiency was increased but Cr(VI) uptake was decreased. Most of Cr(VI) was adsorbed at early reaction stage(1 h) and adsorption equilibrium was established at 5 h. On the other hand, chicken feather adsorbed effectively oils including bunker-A and bunker-C. In conclusion, our results suggest that chicken feather waste could be used to remove heavy metal and oil; it is a potential candidate for biosorption material.

• Journal of Microbiology and Biotechnology
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• 제29권10호
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• pp.1522-1542
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• 2019

To adapt to environmental changes and to maintain cellular homeostasis, microorganisms adjust the intracellular concentrations of biochemical compounds, including metal ions; these are essential for the catalytic function of many enzymes in cells, but excessive amounts of essential metals and heavy metals cause cellular damage. Metal-responsive transcriptional regulators play pivotal roles in metal uptake, pumping out, sequestration, and oxidation or reduction to a less toxic status via regulating the expression of the detoxification-related genes. The sensory and regulatory functions of the metalloregulators have made them as attractive biological parts for synthetic biology, and the exceptional sensitivity and selectivity of metalloregulators toward metal ions have been used in heavy metal biosensors to cope with prevalent heavy metal contamination. Due to their importance, substantial efforts have been made to characterize heavy metal-responsive transcriptional regulators and to develop heavy metal-sensing biosensors. In this review, we summarize the biochemical data for the two major metalloregulator families, SmtB/ArsR and MerR, to describe their metal-binding sites, specific chelating chemistry, and conformational changes. Based on our understanding of the regulatory mechanisms, previously developed metal biosensors are examined to point out their limitations, such as high background noise and a lack of well-characterized biological parts. We discuss several strategies to improve the functionality of the metal biosensors, such as reducing the background noise and amplifying the output signal. From the perspective of making heavy metal biosensors, we suggest that the characterization of novel metalloregulators and the fabrication of exquisitely designed genetic circuits will be required.

• 상하수도학회지
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• 제20권4호
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• pp.637-643
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• 2006

The bench-scale chlorine exposure study was performed to investigate the effect of pretreatment by free chlorine and monochloramine ($NH_2Cl$) on the performance of RO membranes made of polyamide (PA). Feed monochloramination at 2mg/L did not cause significant productivity loss compared to free chlorine. However, metal coagulants reacted with monochloramine, the PA membrane suffered from a gradual loss of membrane integrity by chlorine oxidation, which was characterized as a decrease in salt rejection. Especially, RO membranes exposed to alum coagulants with monochloramine revealed the salt rejection lower than those exposed to iron coagulants. XPS membrane surface analysis demonstrated that the chlorine uptake on the membrane surface increased and carbon peaks were shifted significantly when exposed to alum coagulants with monochloramine.

• 한국결정성장학회지
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• 제20권2호
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• pp.74-79
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• 2010

The synthesis and reactivities of molybdenum carbide crystallites were examined in this study. Especially, the effect of synthesis conditions were scrutinized on the preparation of molybdenum carbide crystallites. In order to perform this purpose, various characterization techniques such as BET surface area and oxygen uptake measurements were employed for the synthesized molybdenum carbide crystallites. First of all, the molybdenum carbide crystallites were synthesized using molybdenum oxide crystallites and methane gas or methane-hydrogen mixture. The experimental results showed that BET surface areas ranged from $7.4m^2/g$ to $31m^2/g$ and oxygen uptake values varied from $8.1{\mu}mol/g$ to $24.3{\mu}mol/g$. The Mo compounds were found to be active for ammonia decomposition reaction. Even though there are some molybdenum carbide crystallites that were exceeded by Pt/$Al_2O_3$ crystallite, the steady state reactivities for other molybdenum carbide crystallites were comparable to or even higher than that determined for the Pt/$Al_2O_3$ crystallite. These results implied that molybdenum carbide crystallites could be one of the promising crystallites that might be substitutes for Pt-like noble metal crystallites in the petroleum processes.

• 한국토양비료학회지
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• 제50권4호
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• pp.251-258
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• 2017

This study was conducted to identify transition characteristics of arsenic (As), cadmium (Cd), and lead (Pb) and to calculate bio-concentration factors (BCF) in the three perennial root medicinal plants, namely Codonopsis lanceolata (Deoduck), Platycodon grandiflorum (Balloon flower) and Panax ginseng (Korean ginseng) grown in major medicinal plant producing districts in Korea. Average BCF values ranged from 0.009~0.029 in As, 0.334~1.453 in Cd, and 0.021~0.023 in Pb in three perennial root medicinal plants. The BCF values increased in the order of ginseng (0.029) > deodeok (0.012) > balloon flower (0.009) for As, balloon flower (1.453) > deodeok (0.685) > ginseng (0.334) for Cd, and ginseng (0.023) > deodeok (0.022) > balloon flower (0.021) for Pb. The BCF values calculated in this study will be useful for predicting the uptake of heavy metal (loid)s. Further study on uptake and accumulation mechanism of toxic metal (loid)s by agricultural products is required to assess the human health risk associated with soil contamination.

• Biomolecules & Therapeutics
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• 제10권4호
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• pp.293-302
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• 2002

The classical concept for iron uptake into mammalian cells has been the endocytosis of transferrin( $T_{f}$ )-bound F $e^{3+}$ via the $T_{f}$ - $T_{f}$ receptor cycle. In this case, we could not explain the uptake of F $e^{2＋}$ ion and the export of iron from endosome. Studies on iron transport revealed that other transport system exists in epithelial cells of the intestine. One of non- $T_{f}$ -receptor-mediated transport systems is Nramp2/DMT1/DCT1 which transports M $n^{＋＋}$, $Mg^{＋＋}$, Z $n^{＋＋}$, $Co^{＋＋}$, N $i^{＋＋}$ or C $u^{＋＋}$ ion as well as F $e^{+2}$ ion. DMT1 was cloned from intestines of iron-deficient rats and shown to be a hydrogen ion-coupled iron transporter and a protein regulated by absorbed dietary iron. DMT1 is founded in other cells such as cortical and hippocampal glial cells as well as endothelial cells in duodenum. Two F $e^{3+}$ ion bound to transferrin( $T_{f}$ ) are taken up via the $T_{f}$ - $T_{f}$ receptor cycle in the intestinal epithelial cell. F $e^{3+}$ in endosome was converted to F $e^{2＋}$ ion, and then exported to cytosol via DMT1. F $e^{2＋}$ ion is taken up into cytosol via DMT1. Several other transporters such as FET, FRE, CCC2, AFT1, SMF, FTR, ZER, ZIP, ZnT and CTR have been reported recently and dysfunction of the transporters are related with diseases containing Wilson's disease, Menkes disease and hemochromatosis. Evidences from several studies strongly suggest that DMT1 is the major transporter of iron in the intestine and functions critically in transport of other metal ions.

• 한국환경농학회지
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• 제40권3호
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• pp.231-238
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• 2021

BACKGROUND: Metal contamination of farmlands nearby abandoned mines is a serious environmental problem. This study was conducted to evaluate the efficiency of stabilizers on different type of the soils contaminated with metals. METHODS AND RESULTS: The texture of silt loam soil initially contaminated with heavy metal was artificially adjusted to loam and sandy loam by adding sand, and the soil organic matter content (1.5%) was also altered by adding peat to the soils at 3.5 and 8.0%. The soils were mixed with 3% (w/w) of each limestone, dolomite, and steel slag. For the soils with different textures, the bioavailability of As was found to be the lowest in sandy loam compared to others metals such as Cu, Pb, and Zn. The efficacy of limestone and dolomite was not significantly different compared to the soils having different organic matter contents, but the stabilization efficiency of steel slag increased as the soil organic matter content increased. Moreover, stabilizers showed inhibition effect on the uptake of metals to plant. CONCLUSION: The stabilizers were found as effective materials to immobilize metals in soil and to decrease plant uptake of metals. Studies are needed to deeply elucidate the interaction between influencing factors and various stabilizers.

• Journal of Microbiology and Biotechnology
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• 제31권8호
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• pp.1045-1059
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• 2021

Various abiotic stressors like drought, salinity, temperature, and heavy metals are major environmental stresses that affect agricultural productivity and crop yields all over the world. Continuous changes in climatic conditions put selective pressure on the microbial ecosystem to produce exopolysaccharides. Apart from soil aggregation, exopolysaccharide (EPS) production also helps in increasing water permeability, nutrient uptake by roots, soil stability, soil fertility, plant biomass, chlorophyll content, root and shoot length, and surface area of leaves while also helping maintain metabolic and physiological activities during drought stress. EPS-producing microbes can impart salt tolerance to plants by binding to sodium ions in the soil and preventing these ions from reaching the stem, thereby decreasing sodium absorption from the soil and increasing nutrient uptake by the roots. Biofilm formation in high-salinity soils increases cell viability, enhances soil fertility, and promotes plant growth and development. The third environmental stressor is presence of heavy metals in the soil due to improper industrial waste disposal practices that are toxic for plants. EPS production by soil bacteria can result in the biomineralization of metal ions, thereby imparting metal stress tolerance to plants. Finally, high temperatures can also affect agricultural productivity by decreasing plant metabolism, seedling growth, and seed germination. The present review discusses the role of exopolysaccharide-producing plant growth-promoting bacteria in modulating plant growth and development in plants and alleviating extreme abiotic stress condition. The review suggests exploring the potential of EPS-producing bacteria for multiple abiotic stress management strategies.

• Horticulture, Environment, and Biotechnology : HEB
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• 제59권6호
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• pp.775-786
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• 2018

To test the hypothesis that humic acid (HA), anaerobically digested pig slurry filtrate (APS), and their combination would differently affect the chemical speciation and extractability of metals (cadmium, copper, and zinc) and their uptake by plants, we conducted a pot experiment using wormwood in two texturally contrasting soils (sandy loam and clay loam) collected from a field near an abandoned Cu mine. Four treatments were laid out: HA at $ 23.5g\;kg^{-1}$ (HA), APS at $330mL\;kg^{-1}$ (APS), HA at $ 23.5g\;kg^{-1}$ and APS at $330mL\;kg^{-1}$ (HA + APS), and a control. Each treatment affected the chemical speciation and mobility of the metals, and thereby resulting in variable patterns of plant biomass yield and metal uptake. The APS supported plant growth by increasing nutrient availability. HA supported or hindered plant growth by impacting the soil's water and nutrient retention capacity and aeration, in a soil texture-dependent manner, while consistently enhancing the immobilization of heavy metals. Temporal increases in whole-plant dry matter yield and metal accumulation suggested that the plants were capable of metal hyperaccumulation. The results were discussed in terms of the mobility of metals and plant growth and corroborated by the $^{15}N$ recovery of soil- and plant-N pools under H and HS treatments. Therefore, for effective phytoremediation of polluted soils, an appropriate combination of plant growth promoters (APS) and chelating agents (HA) should be predetermined at the site where chemical stabilization of pollutants is desired.

• Applied Biological Chemistry
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• 제39권6호
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• pp.494-500
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• 1996

중요한 환경문제로 대두되고 있는 중금속 오염의 대처 방안으로 식물을 이용한 경제적인 정화 방법을 모색하고자 미나리의 중금속 흡수능력을 검정하고 카드늄 결합단백질을 동정하였다. 미나리의 중금속 흡수능력은 미나리를 카드늄 $(Cd^{2+})$, 크롬 $(Cr^{3+})$ 및 납 $(Pb^{2+})$의 농도를 달리한 배양액에서 재배한 후 미나리에 잔류하는 중금속을 정량함으로써 측정되었다. 중금속의 처리 기간은 3일과 7일로 하였고, 생장 저해가 일어나는 농도까지 처리하였다. 카드늄은 16.68 ppm, 크롬은 20 ppm까지 지속적으로 잔류량이 증가하였고 그 농도 이상에서는 생장 저해가 일어나면서 잔류량의 증가율이 둔화되었다. 식물체 부위별 카드늄과 크롬의 잔류량은 뿌리에서 월등하게 높게 나타났고 줄기와 잎의 순으로 낮아졌다. 납의 경우는 카드늄과 크롬에 비하여 잔류량이 가장 높은 뿌리에서 4배 정도 잔류량이 높게 나타났다. 20 ppm의 중금속 용액에서 7일간 재배한 미나리 뿌리에는 건조중량 1 g에 대하여, 카드늄이 6.1 mg, 크롬은 5.2 mg 그리고 납은 23.6 mg이 잔류하고 있었다. 이것은 잔류하고 있는 중금속 중에서 카드늄은 80%, 크롬은 92%그리고 납은 96%이상이 미나리 뿌리에 잔류하고 있는 것이다. 20 ppm카드늄이 함유된 배양액에서 7일간 자란 미나리 뿌리 추출액을 Sephadex G-50과 DEAE-Cellulose 크로마토그래피를 수행하여, polyacrylamide gel 전기영동 상으로 단일 단백질 분리대의 중금속 결합단백질을 정제하였다. 이 단백질의 분자량은 gel filtration 상에서 약 5,000 Da이었고 아미노산의 조성을 보면 산성 아미노산이 27.3%, cystein이 9.9%로서 중금속 결합단백질의 특성을 가지고 있었다. 그러나 그 아미노산 조성은 지금까지 알려진 phytochelatin과는 다른 새로운 중금속 결합단백질로 나타났다.