• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.5
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• pp.141-153
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• 2004

Wetland system is widely accepted as one of natural water purification systems around the world for nonpoint sources pollution control. Constructed wetlands have become a popular technology for treating contaminated surface and waste water. In this study, the field experiment to reduce nonpoint source pollution loadings from polluted stream waters using wetland system was performed from June 2002 to March 2004. Four wetlands were used and the size of each one was 0.8ha. Water of Dangjin stream flowing into Seokmun estuarine reservoir was pumped into wetlands. Inflow and hydraulic residence time of the system was 500 $m^3$/day∼1,500 $m^3$/day, 2∼5 days, respectively. After 2 year operation, plant-coverage of the wetlauds was about 70% from bare soil surface at initial stage . Average water quality of the influent was $BOD_5$ 4.17 mg/L, TSS 18.45 mg/L, T-N 4.32 mg/L, and T-P 0.30 mg/L. The average removal rate of $BOD_5$, TSS, T-N and T-P during the study period was 5.6%, 46.6%, 45.7%, and 54.8%, respectively. Organic ($BOD_5$) removal rate was low and the reason might be low influent concentration. Wetland removal rate of T-P was about 10% higher than T-N. Performance of the experimental system was compared with existing data base (NADB), and it was within the range of general system performance. Overall, the wetland system was found to be adequate for treating polluted water stream with stable removal efficiency even during the winter period. Most of the nonpoint source pollutions from watershed are transported by streams or ditches, and they could be controled by constructed wetland system before entering the lake or reservoir.

• Journal of Ecology and Environment
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• v.33 no.1
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• pp.15-18
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• 2010

Mangroves are special plant communities that live along intertidal zones in tropical and subtropical areas. They are regarded as one of the most important types of natural ecosystem in the world because of the many ecosystem functions that they perform, of which water purification is the most complex. Mangrove ecosystems are conducive to the deposition and retention of heavy metals. So it is important to understand the impact of heavy metals on mangrove ecosystems, and especially on soil subsystems. We examined the levels of heavy metals in the soil of mangroves in the Dongzhaigang Mangrove National Nature Reserve. Dongzhaigang, the first mangrove nature reserve established in China, is located south of Haikou in Hainan Island and encompasses $33.37\;km^2$, of which mangroves comprise $20.56\;km^2$. To assess the impact of human activities, we collected a large number of soil samples in four sampling areas (the protection station, the harbor, a tour area, and Yeboluo island) in the study area. We measured the concentrations of Cu, Pb, Zn and Cd in the soil samples using the spectra of polyatomic molecules. The average concentrations of Cu, Pb, Zn and Cd were $5.04\;{\mu}g/g$, $10.36\;{\mu}g/g$, $20.06\;{\mu}g/g$ and $0.06\;{\mu}g/g$, respectively, and the heavy metal concentrations were lowest in the protected area, highest in the harbor, and intermediate in Yeboluo Island and the tour area. The heavy metal concentrations in the soil collected from different sample plots are related not only to the physical and chemical properties of the soil, but also to the heavy metal emitted by nearby pollution sources. Our analysis indicates that tourist boats are the main pollution sources in the study area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.4
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• pp.456-464
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• 1996

Fructans are the major vegetative storage carbohydrate in wheat(Triticum aestivum L.). The depolymerization of fructans occurs by the sequential removal of terminal fructosyl residues by a specific fructan exohydrolase(FEH). The objective of this study was to isolate and characterize this enzyme in wheat. From stems and sheaths of field-grown wheat(cv. Clark), FEH was purified 356-fold using salt precipitation and a series of chromatographic procedures including size exclusion, anion exchange, and affinity chromatography. FEH had a molecular weight of 63.7 kD and an optima at pH 5.5 and 3$0^{\circ}C$. The $K_{m}$s for $\beta$(2 longrightarrow1) linked oligofructans varied, from 10 to 37mM, with the lowest $K_{m}$ for tetrasaccharide. The $V_{max}$ increased as degree of polymerization (DP) increased. Wheat FEH hydrolyzed only, $\beta$(2 longrightarrow1) linked fructans but not, $\beta$(2 longrightarrow6) linked timothy fructan or sucrose. The role of this FEH in fructan metabolism in wheat is discussed.sed.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.10
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• pp.580-587
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• 2016

This study aims to estimate the values of freshwater ecosystem services from demand and supply perspectives. From demand side, unit-values of ecosystem services are derived from Environmental Valuation Information System (EVIS) and aggregated to 5 main watersheds in Korea. The derived unit-values are based on the willingness to pay estimates per household from stated preference methods. The nation-wide average total values of water quantity supply, water purification, and natural disaster control are estimated as 501.2, 410.4, and 242.4 billion won/year, respectively. From supply side, we examine the direct and indirect public expenditures (or investment) in 2013 to improve freshwater ecosystem services by the government. The total sum of government expenditures corresponds to 8,882 billion won in 2013, where 12.9, 81.3, 0.3 and 5.3% are spent to improve provisioning, regulating, supporting and cultural services, respectively, indicating that most efforts are concentrated in enhancing regulating services.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.2
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• pp.75-86
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• 2008

The wetlands have functions those were retention of diverse biota, purification of water quality, control of climate and flood, eco-tourism and supply of agricultural water, and that was the ecosystem of high biodiversity as the zone of transition between inland and water. Therefore, this study showed the conservation and management plan by analyzing in the abiotic and biotic environment of forest swamp, Gyeongsangbuk-do. The results were as follows. Examining the management plan of the abiotic environment, there will need to establish the hydrological plan in continuous expediting the supply of water to maintain a humid soil of swamp, and to try to find the organic farming, use of low toxic agrichemicals and so on to prevent occurring a non-point source pollutants. To prevent changing the flowing of ground water and inflow of earth and sand in modifying the land character, there will be needed to restrict the construction of farmland and slope around swamp. To manage the biotic environment, there needed to offer the habitat by removing the regular interval and individual of a dead tree, and to improve the growth environment of vegetation. Because the naturalized plants disturb the natural vegetation, they will be removed. The afforested trees like Robinia pseudoacacia and Amorpha truticosa will be renewed to prevent the heterogeneity of landscape ecology, and the active conservation plan on wetland species will be established. As this study was carried out to study on the partial swamp, Gyeongsanbuk-do, the ecological environments distributing a swamp in Korea show a some problem. In the future, the study will accomplish to study the accurately and objectively ecological environment and management of a swamp by analyzing the extensive sites.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.4
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• pp.370-375
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• 2014

BACE2 is a membrane-bound aspartic protease that is highly homologous with BACE1. While BACE1 processes the amyloid precursor protein (APP) at a key step in generating ${\beta}$-amyloid peptide and presumably causes Alzheimer's disease (AD), BACE2 has not been demonstrated to be involved in APP processing directly, and its physiological functions are unknown. To determine its function and to develop inhibitors from marine sources, we constructed an overexpression vector for producing BACE2. The gene encoding human BACE2 protease was amplified using the polymerase chain reaction and cloned into the pET11a expression vector, resulting in pET11a/BACE2. Recombinant BACE2 protease was overexpressed successfully in E. coli as inclusion bodies, refolded using the rapid-dilution method, and purified via two-step fast protein liquid chromatography using Sephacryl S-300 gel filtration and Resource-Q column chromatography. The BACE2 protease produced was an active form. This study provides an efficient method not only for studying the basic properties of BACE2, but also for developing inhibitors from natural marine sources.

• Journal of Microbiology and Biotechnology
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• v.9 no.2
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• pp.173-178
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• 1999

The extracellular cytosine deaminase (EC 3.5.4.1) from Chromobacterium violaceum YK 391 was purified 264.7-fold with an overall yield of 14.3%. The enzyme was for the first time homogeneous by the criteria of polyacrylamide gel electrophoresis performed in the absence and in the presence of sodium dodecyl sulfate. The molecular weight of the purified enzyme was estimated to be about 156 kDa. The enzyme consisted of two identical subunits of approximate molecular weight 78 kDa. The isoelectric point of the enzyme was pH 5.55. The enzyme had a pH optimum of 7.5 and a temperature optimum of around 40 to $45^{\circ}C$. Besides cytosine, the enzyme deaminated 5-fluorocytosine, cytidine, 5-methylcytosine, and 6-azacytosine, but not 5-azacytosine. The extracellular cytosine deaminase is believed to be unique because it was active not only on cytosine but also on cytidine. The apparent $K_m$ values for cytosine, 5-fluorocytosine, cytidine, and 5-methylcytosine were determined to be 1.55 mM, 5.52 mM, 10.4 mM, and 67.2 mM, respectively. The enzyme activity was strongly inhibited by heavy metal ions such as $Fe^{2+},Pb^{2+},Cd^{2+},Zn^{2+}, Hg^{2+}, and Cu^{2+}$ at 1 mM, and completely by $\alpha,\alpha$'-dipyridyl, and $\rho$-chloromercuribenzoate at 1 mM, and weakly inhibited by 1mM ο-phenanthroline. The enzyme activity was not affected by various nucleosides and nucleotides.

• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.461-468
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• 2016

In recent years, various naturally occurring defence peptides such as plectasin have attracted considerable research interest because they could serve as alternatives to antibiotics. However, the production of plectasin from natural microorganisms is still not commercially feasible because of its low expression levels and weak stability. A tandemly arrayed plectasin gene (1,002 bp) from Pseudoplectania nigrella was generated using the isoschizomer construction method, and was inserted into the pPICZαA vector and expressed in Pichia pastoris. The selected P. pastoris strain yielded 143 μg/ml recombinant plectasin (Ple) under the control of the methanol-inducible alcohol oxidase 1 (AOX1) promoter. Ple was estimated by SDS-PAGE to be 41 kDa. In vitro studies have shown that Ple efficiently inhibited the growth of several gram-positive bacteria such as Streptococcus suis and Staphylococcus aureus. S. suis is the most sensitive bacterial species to Ple, with a minimum inhibitory concentration (MIC) of 4 μg/ml. Importantly, Ple exhibited resistance to pepsin but it was quite sensitive to trypsin and maintained antimicrobial activity over a wide pH range (pH 2.0 to 10.0). P. pastoris offers an attractive system for the cost-effective production of Ple. The antimicrobial activity of Ple suggested that it could be a potential alternative to antibiotics against S. suis and S. aureus infections.

• Journal of the Korean Institute of Landscape Architecture
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• v.32 no.3
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• pp.43-50
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• 2004

This study looked into the water quality improvement effect of reed (Phragmites communis), bur reed (Sparaganium stoloniferum), Alisma canaliculatum, and Hydrocharis dubia in order to develop native hydrophytes suitable to natural-type wetlands for ecological restoration. The result confirms that the concentration of wastewater was lowered in most plants indicating a possibility in wastewater treatment. Among four species, reed (Phragmites communis) and bur reed (Sparaganium stoloniferum) were most effective in removing a majority of contaminants. Considering that reed (Phragmites communis) is a species that has been used most often among hydrophytes, bur reed (Sparaganium stoloniferum), which is a native species in Korea, showed equivalent level of outstanding effect. In the physiological and growing activity and its relations to water quality improvement effect, each species appeared differently. Reed (Phragmites communis) and bur reed (Sparaganium stoloniferum) were best also in physiological and growing activity. In the case of Hydrocharis dubia, growth was strong in polluted water environment but its physiological activity was poor, indicating that it was under stress. The growth and physiological activity of Alisma canaliculatum were also poor, indicating that it too is being stressed. However, measuring organic contents in the plants of each species shows that the organic contents of Alisma canaliculatum was high. Alisma canaliculatum is a species effective in removing pollutants in water, although it is under stress. A unique phenomenon in removing water pollution with plants is that each species removed different pollutants. In the case of Alisma canaliculatum, which was relatively poor in removing pollution, it was remarkable in reducing nitrogen and phosphorus. Hydrocharis dubia was also effective in eliminating floating matter.

• Korean Chemical Engineering Research
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• v.47 no.2
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• pp.258-261
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• 2009

In this work, we the ettect on extraction amounts and general composition content of phytoestrogen genistein and formononetin extracted from Sophoraflavescens Aiton by various ultrasonic waves(35, 72, and 170 KHz) and extraction time(30, and 60 min) were compared using extraction solvent water 100%. The pretreatment step was composed of ultrasonic waves extraction, filtration, concentration, and membrane filtration. The extracted sample was analyzed by reversed-phase high performance liquid chromatography(RP-HPLC). And the mobile phase applied was linearly changed with A/B of 80/20~65/35 vol% for 60 min(A water/acetic acid, 99.9/0.1 vol%, B acetonitrile/acetic acid, 99.9/0.1 vol%). The experimental results, general composition carbohydrate(0.255 to 0.413%) excepts, other ingredients was confirmed almost similarly. Also, The highest yield of extraction amount 3.17g was obtained by ultrasonic waves with a frequency of 170 KHz and an extraction time of 60 min. This work offers would be useful for chemical and biological studies of natural plants and its products.