• Korean Journal of Food Science and Technology
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• v.17 no.2
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• pp.121-127
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• 1985

In studying the structural work on ciguatoxin, parrot fish collected were identified as Scarus sordidus, S. frenatus, S. scaber and S. pectarlis, in which only S. sordidus contained toxic materials. Crude toxins obtained by silicic acid column chromatography, could be separated on a DEAE-cellulose column into two fractions, ST-1(less polar) and ST-2(polar) eluted with chloroform and chloroform-methanol(1:1). Furthermore ST-1 could be changed into ST-2 by repeated chromatography on DEAE-cellulose. Rf values of ST-1 and ST-2 were 0.60-0.75 and 0.30-0.54 on TLC coated with silica gel 60F-254 developed by chloroform-methanol-water-acetic acid (90:9.5:0.2:0.3) mixture. The peaks of ST-1 and ST-2 were not observed on each HPLC chromatogram at low sensitivity(2X), but by bioassay they were detected in the fraction of 24-27ml(less polar toxin, 120ng) and 22-27 ml (polar toxin, 150 ng). Less polar ciguatoxin from morey eel viscera also showed its peak in the same elution volume(25ml). Being subjected to chromatography on basic aluminum oxide (activity grade I) or to alkaline treatment, followed by basic aluminum oxide (activity grade I) chromatography ST-1 toxin was remarkably converted into the polar toxic component supposed to be polar ciguatoxin in both cases. In the latter case, approximately 74% of the residual toxicity was changed into the polar component, accompanied by about 50% loss of the initial toxicity. More than 26% of ST-2 toxicity was transformed into the less polar toxic component supposed to be less polar ciguatoxin on a deactivated aluminum oxide (activity grade V) column.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.2
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• pp.207-215
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• 2014

Wastewater containing heavy metals such as copper (Cu) and nickel (Ni) is harmful to humans and the environment due to its high toxicity. Crystallization in a fluidized bed reactor (FBR) has recently received significant attention for heavy metal removal and recovery. It is necessary to find optimum reaction conditions to enhance crystallization efficacy. In this study, the effects of crystallization reagent and pH were investigated to maximize crystallization efficacy of Cu-S and Ni-S in a FBR. CaS and $Na_2S{\cdot}9H_2O$ were used as crystallization reagent, and pH were varied in the range of 1 to 7. Additionally, each optimum crystallization condition for Cu and Ni were sequentially employed in two FBRs for their selective removal from the mixture of Cu and Ni. As major results, the crystallization of Cu was most effective in the range of pH 1-2 for both CaS and $Na_2S{\cdot}9H_2O$ reagents. At pH 1, Cu was completely removed within five minutes. Ni showed a superior reactivity with S in $Na_2S{\cdot}9H_2O$ compared to that in CaS at pH 7. When applying each optimum crystallization condition sequentially, only Cu was firstly crystallized at pH 1 with CaS, and then, in the second FBR, the residual Ni was completely removed at pH 7 with $Na_2S{\cdot}9H_2O$. Each crystal recovered from two different FBRs was mainly composed of CuxSy and NiS, respectively. Our results revealed that Cu and Ni can be selectively recovered as reusable resources from the mixture by controlling pH and choosing crystallization reagent accordingly.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.236-246
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• 2014

Pesticide is used to protect the crops, but also become a cause of polluting the environment. Perform a risk assessment using physical and chemical properties, environmental fate and toxicity data in order to determine the pesticide registration. The aquatic model estimates pesticide concentrations in water bodies that result from pesticide applications to rice paddies and apple orchard. The used models are the PRZM, EXAMS and AGRO shell (PA5), Rice Water Quality Model (RICEWQ) and Screening Concentration In GROund Water (SCI-GROW). The residual concentration of water body was estimated using meteorological data, crop calendar and soil series of Korea. The chosen pesticides were butachlor, carbofuran, iprobenfos and tebuconazole. It has shown the potential that the RICEWQ is possible to predict residue level in water of butachlor and iprobenfos, because the maximum value in water monitoring data is lower than the peak concentration of the model, and the minimum value is lower than the average annual concentration of the model. But RICEWQ was insufficient to predict exposure concentrations in ground water. The estimated exposure concentrations of carbofuran in ground water is very higher than in surface water because of its low soil adsorption coefficient. Although tebuconazole were not detected in the water monitoring that means very low concentration, it is possible that the PA5 can be used to predict residue level in water.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1072-1080
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• 2005

The extraction characteristics of heavy metals(HM) from a contaminated soil at existing lead smelters were investigated with ethylene diamine tetraacetic acid(EDTA), citrate and HCl as washing solutions. EDTA was more effective for Pb than for other heavy metals. As the mol ratio of EDTA/HM increased, the removal efficiency of heavy metals became higher. When the mol ratio of EDTA/HM approached to 6.5, it removed Pb most effectively. Citrate was effective especially in extracting Zn. The removal efficiency of HCl was comparatively high in almost all heavy metals, and at 0.3N concentration it was the highest. After soil washing process by the use of EDTA, the great part of exchangeable fractions and most of heavy metals of weakly adsorbed like carbonate fraction were extracted. For washing with citrate and HCl, four heavy metals showed the similar exchange of chemical partitioning and the exchangeable fractions of Pb which has weakly adsorbed to soil were more increased than before the process. As removal efficiency of citrate washing process depends upon the distribution of non-detrital fractions, so it can be contended that only the amount of non-detrital fractions could be removed from all the heavy metal content. EDTA and HCl could remove most of non-residual fractions in all heavy metals except Zn. As a result of EDTA washing, toxicity characteristic leaching procedure(TCLP) concentration of the processed soil met the USEPA Pb limit of 5.0 mg/L.

• Journal of Life Science
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• v.28 no.4
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• pp.483-487
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• 2018

Cypermethrin, a commonly used domestic and agricultural pyrethroid pesticide, is widely considered detrimental to the environment and to many organisms because of its residual property and toxicity. Cellulophaga lytica DAU203, isolated from coastal sediment, was chosen because it degrade cypermethrin. Cellulophaga lytica DAU203 effectively degraded cypermethrin, as the utilized carbon source and substrate, in a mineral salt medium. Effective factors, such as carbon source, nitrogen source, initial pH, and temperature, for cypermethtin biological degradation by Cellulophaga lytica DAU203 were analyzed by one factor at a time method. Temperature ($22{\sim}42^{\circ}C$), initial pH (5~9), and yeast extract concentration (0.1~2.5%[w/v]) were selected as the three most important factors. There were optimized at $33.4^{\circ}C$, pH 7.7, and 2.4%(w/v) by response surface methodology, respectively. The Box- Behnken design consisting of 46 experimental runs with three replicates was used to optimize the independent variables which significantly influenced the cypermethrin biological degradation. This model for cypermethrin degradation by Cellulophaga lytica DAU203 is highly significant (p<0.05). Under the optimized condition, Cellulophaga lytica DAU203 degraded approximately 83.7 % of the cypermethrin within 5 days. These results suggest that Cellulophaga lytica DAU203 may be useful for the biological degradation of cypermethrin in cypermethrin-contaminated environments.

• Journal of Life Science
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• v.19 no.10
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• pp.1389-1395
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• 2009

Generally, it takes a long time to purify wood vinegar, and it contains toxic compounds such as tar, methanol, phenol and benzopyrene. To reduce the toxicity of wood vinegar itself, we have developed a new purification method of wood vinegar using an oxidation-cohesion reaction and distillation with an active carbon. We have investigated the physico-chemical change (pH, specific gravity, refractive index and dissolved tar), the change of amount of toxic compounds (carbonyl group, phenol, benzopyrene and residual solvents) and organic acids (formic acid (FA), acetic acid (AA), propionic acid (PA)) of the purified wood vinegar under the long term and accelerated storage conditions. Also, we have evaluated the effect of the purified wood vinegar on hair growth using an alopecia model of C57BL/6 mice. As a result, we could find out that the purified wood vinegar was stable and remained without decay under the storage conditions and benzopyrene, a carcinogenic agent, was not detected in the purified wood vinegar. After topical treatment of the purified wood vinegar solution or minoxidil (MXD) for 2 weeks to dorsal skin, the hair regrowth of the mice accelerated faster than that of the control, with no clinical signs. In conclusion, we could suggest a guideline for quality control of process to reduce the toxic compounds in wood vinegar and it might be a useful hair growth promoter in the treatment of baldness or alopecia.

• Applied Biological Chemistry
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• v.43 no.3
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• pp.190-195
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• 2000

Tolaasin is a peptide toxin produced by Pseudomonas tolaasii and causes a brown blotch disease forming brown, slightly sunken spots and blotches on the cultivated mushrooms. It is a lipodepsipeptide consisting of 18 amino acids and its molecular mass is 1,985 Da. It forms a pore in plasma membranes, resulting in the disruption of membranes of fungal, bacterial, plant, and animal cells as well as mushroom tissue. In order to measure the toxicity of tolaasin, erythrocytes of blood were used to evaluate the tolaasin-induced hemolysis. Hemolytic activity of tolaasin was measured by observing the absorbance change either at 420 nm, representing the release of hemoglobins from red blood cells(RBCs), or at 600 nm, representing the density of residual cells. The hemolytic activity of culture-extract of P. tolaasii increased at early-stationary phase of growth and was maximal at late stationary phase. The hemolytic activity of tolaasin appeared high in the RBCs of dog and rat. The RBCs of rabbit and hen were less susceptible to tolaasin. The effects of various cations were also measured. $Cd^{2+}$ and $La^{3+}$. as well as $Zn^{2+}$ appeared inhibitory to the tolaasin-induced hemolysis. The effects of various anions on tolaasin-induced hemolysis were measured and carbonate showed the greatest inhibition to the hemolysis. However, phosphate stimulated the tolaasin-induced hemolysis and no effects were observed by chloride and nitrate.

• Research in Plant Disease
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• v.27 no.4
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• pp.129-136
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• 2021

Rice is responsible for the stable crop of 3 billion people worldwide, about half of Asian depends on it, and rice is grown in more than 100 countries. Rice diseases can lead to devastating economic loss by decreasing yield production, disturbing a stable food supply and demand chain. The most commonly used method to control rice disease is chemical control. However, misuse of chemical control can cause environmental pollution, residual toxicity, and the emergence of chemical-resistant pathogens, the deterioration of soil quality, and the destruction of biodiversity. In order to control rice diseases, research on alternative biocontrol is actively pursued including microorganism-oriented biocontrol agents. Microbial agents control plant disease through competition with and antibiotic effects and parasitism against plant pathogens. Microorganisms isolated from the rice rhizosphere are studied comprehensively as biocontrol agents against rice pathogens. Bacillus sp., Pseudomonas sp., and Trichoderma sp. were reported to control rice diseases, such as blast, sheath blight, bacterial leaf blight, brown spot, and bakanae diseases. Here we reviewed the microorganisms that are studied as biocontrol agents against rice diseases.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.363-370
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• 2013

Susceptibility of each developmental stage of Phthorimaea operculella (Lepidoptera: Gelechiidae) were investigated using 16 insecticides which are available in the market in Korea. For the eggs and pupae, only spinosad showed a 71.1% inhibition rate for egg hatchability and a 66.7% inhibition rate for emergence. For the 3rd instar larvae, the feeding toxicities were over 90% for fenitrothion ($LC_{50}$ 336.6 ppm), esfenvalerate ($LC_{50}$ 8.6 ppm), ethofenprox ($LC_{50}$ 35.7 ppm), and emamectin benzoate ($LC_{50}$ 0.05 ppm). Furthermore, the contact toxicities were over 90% for esfenvalerate ($LC_{50}$ 0.87 ppm), ethofenprox ($LC_{50}$ 16.5 ppm), emamectin benzoate ($LC_{50}$ 0.53 ppm), and spinosad ($LC_{50}$ 2.48 ppm) at the recommended concentrations. Deltamethrin and spinosad yielded 100% mortality for adult P. operculella 48 h after treatment. The adult female fecundity was inhibited by deltamethrin, esfenvalerate, emamectin benzoate, spinosad and dinotefuran, which were significantly different from the control. The adult longevities (7.3-8.3 days) were reduced by approximately 1-2 days compared with the control (9.3 day). The emamectin benzoate maintained 100% insecticidal activity 14 days after treatment and ethofenprox maintained over 90% activity 7 days after treatment.

• Journal of Life Science
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• v.18 no.6
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• pp.789-795
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• 2008

To study the possible use of probiotics in fish farming, we evaluated antagonism of antibacterial strain Bacillus amyloliquefaciens H41 against the fish pathogenic bacterium Vibrio anguillarum NCMB1. The purification of growth inhibition factor produced by B. amyloliquefaciens H41 was achieved by obtaining supernatant of this bacterium. The growth inhibition factor was purified to homogeneity by 70% ammonium sulfate precipitation, DEAE-sephadex A-50 ion exchange chromatography, sephadex G-200 gel filtration column chromatography, and sephadex G-50 gel filtration column chromatography with 40.8 fold of purification and 2.9% yield. The molecular weight of the purified growth inhibition factor was 48 kDa as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The optimum pH and temperature for the growth inhibition factor were pH 7.5 and $30^{\circ}C$, respectively. The activity of growth inhibition factor was enhanced slightly by some metal ions, such as $Mg^{+2}$, $Mn^{+2}$, but was inhibited by the addition of $Co^{+2}$, $Hg^{+2}$, $Zn^{+2}$ and $Ag^{+2}$. NaCl stability of the growth inhibition factor was observed with 50% residual activity at 3% NaCl concentration. Toxicity test showed that the purified B. amyloliquefaciens H41 growth inhibition factor did not affect the live of Japanese flounder (Paralichthys olivaceus) and the effectiveness was 78% of residual lethality compared to commercial antibacterial agents.