• Journal of Life Science
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• v.26 no.4
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• pp.453-459
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• 2016

Agarases are classified into α-agarase and β-agarase that produce agarooligosaccharides and neoagarooligosaccharides, respectively. Neoagarooligosaccharides have whitening effect of skin, delay of starch degradation, and inhibition of bacterial growth etc. Hence, the object of this study was to isolate a novel agarase producing marine bacterium and characterization of its β-agarase. A novel agar-degrading bacterium was isolated from seashore of Namhae at Gyeongnamprovine, Korea and purely cultured with Marine agar 2216 media. The isolated bacterium was identified as Simiduia sp. SH-4 after 16S rRNA gene sequencing. The enzymatic sample was obtained from culture media of Simiduia sp. SH-4. Enzymatic activity was highly increased from 20(30% relative activity) to 30℃ (100%) and decreased from 30 to 40℃(75%) and so more. Relative activity was 100% at pH 6 while those were about 91% and 59% at pH 5.0 and 7.0, respectively, meaning the enzyme possesses narrow optimal pH range. Hence, the enzyme exhibited the maximal activity with 120.4 units/l at pH 6.0 and 30℃ in 20 mM Tris-HCl buffer. Thin layer chromatography (TLC) analysis showed that Simiduia sp. SH-4 produces β-agarase, which hydrolyze agarose to produce biofunctional neoagarooligosaccharides such as neoagarotetraose and neoagarobiose. Hence, broad applications would be possible using Simiduia sp. SH-4 and its enzyme in the food industry, cosmetics and medical fields.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.10
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• pp.1460-1466
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• 2016

This study was conducted to develop a savory ingredient using rice material. We made hydrolysates with ratios of rice bran and rice protein of 4:0, 3:1, 2:2, and 1:3 (w/w) using commercial enzymes, and then investigated their quality properties. At a ratio of 3:1, nitrogen degradation ratio (NDR), savory taste, and overall acceptability were the highest compared to other ratios. Rice bran and rice protein with a ratio of 3:1 were hydrolyzed for 13 days, and characteristics of the hydrolysate were investigated after 3, 5, 7, 10, and 13 days. Total nitrogen, amino nitrogen, and NDR of the hydrolysate after 10 days were higher than those of other hydrolysates. SDS-PAGE showed that the molecular weight of the hydrolysate peptide became smaller as hydrolysis time increased. Glutamic acid content was highest among all amino acids in the hydrolysate for 13 days. Amino acids related to bitter taste decreased from 5 to 13 days, whereas amino acids related to sweet taste substantially increased over time. Sensory evaluation showed that the hydrolysate after 10 days was best. These results suggest that rice bran and rice protein at a mixing ratio of 3:1 and hydrolysis for 10 days were optimal hydrolysis condition for development of natural savory ingredients.

• Journal of Soil and Groundwater Environment
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• v.17 no.2
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• pp.15-21
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• 2012

MTBE (Methyl tertiary-butyl ether) has been commonly used as an octane enhancer to replace tetraethyl lead in gasoline, because MTBE increases the efficiency of combustion and decreases the emission of carbon monoxide. However, MTBE has been found in groundwater from the fuel spills and leaks in the UST (Underground Storage Tank). Fenton's oxidation, an advanced oxidation catalyzed with ferrous iron, is successful in removing MTBE in groundwater. However, Fenton's oxidation requires the continuous addition of dissolved $Fe^{2+}$. Zero-valent iron is available as a source of catalytic ferrous iron of MFO (Modified Fenton's Oxidation) and has been studied for use in PRBs (Permeable Reactive Barriers) as a reactive material. Therefore, this study investigated the condition of optimization in MFO-PRBs using waste zero-valent iron (ZVI) with the waste steel scrap to treat MTBE contaminated groundwater. Batch tests were examined to find optimal molar ratio of MTBE : $H_2O_2$ on extent to degradation of MTBE in groundwater at pH 7 with 10% waste ZVI. As the results, the ratio of optimization of MTBE to hydrogen peroxide for MFO was determined to be 1:300[mM]. The column experiment was conducted to know applicability of MFO-PRBs for MTBE remediation in groundwater. As the results of column test, MTBE was removed 87% of the initial concentration during 120days of operational period. Interestingly, MTBE was degraded not only within waste ZVI column but also within sand column. It means the aquifer may affect continuously the MTBE contaminated groundwater after throughout the waste ZVI barrier. The residual products showed acetone, TBF (Tert-butyl formate) and TBA (Tert-butyl acetate) during this test. The results of the present study showed that the recycled materials can be effectively used for not only a source of catalytic ferrous iron but also a reactive material of the MFO-PRBs to remove MTBE in groundwater.

• Journal of Korea Multimedia Society
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• v.12 no.11
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• pp.1593-1608
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• 2009

If a certain relay node in multi-hop wireless networks might become a malicious node that does not cooperate with other nodes or a selfish node, network throughput will be dramatically decreased. Most of existing ad hoc routing protocols assuming that the nodes will fully cooperate with other nodes do not resolve the problem of network performance degradation due to malicious and selfish nodes. This paper presents the CARE (Cooperative Ad hoc routing protocol based REputation) scheme incorporating the reputation management that can achieve a multi-hop wireless network with high throughput performance. The proposed scheme provides the horizontal cross-layer approach which can identify misbehaving malicious, selfish nodes dropped out of the hop-by-hop based packet processing in the network and then set up an optimal packet routing path that will detour misbehaving nodes. And the vertical cross-layer approach contained in the CARE scheme attempts to improve the quality of routing paths by exploiting the quality of link information received from the MAC layer. Besides, it provides high TCP throughput by exploiting the reputation values of nodes acquired from the network layer into the transport layer. A case study on experiments and simulations shows that the CARE scheme incorporating vertical and horizontal cross-layer approaches yields better performance in terms of the low rate of packet loss, fast average packet delivery time, and high TCP throughput between end-to-end nodes.

• Journal of Conservation Science
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• v.32 no.3
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• pp.385-394
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• 2016

A fabric excavated from tombs or passed down is not easy to find its original color as it degrades and discolors by UV and visible rays, oxygen and microorganisms. LC-MS analysis is commonly used for separating and analyzing colors, but color extraction process is complicated and important in dye-qualitative analysis. To extract red colors from a fabric which is dyed with safflower and lac, solvents; hydrogen chloride, pyridine and oxalic acid are used and oxalic acid was the most effective solvent. Meanwhile, dyed samples were put in degradation condition; UV-A for 168 hours and analyzed with LC-MS to find out its colors'chemical changes. As a result, carthamin is detected in $T_R$ 13 min and laccaic acid A is detected in $T_R$ 10 min. However carthamin is not detected in a degraded fabric dying with safflower, it could be identified as a safflower fabric by the molecular weight of m/z 931. Through this study the most optimal method for red color extraction is found so it is expected to be used as a base line data for red color LC-MS analysis.

• Korean Journal of Environmental Agriculture
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• v.11 no.1
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• pp.59-66
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• 1992

An enzyme immunoassay(EIA) was developed for the analysis of insecticide endosulfan and its degradation products. The sensitivity and specificity of the antibody produced were examined. Optimal conditions in the ELISA system for residue analysis were also discussed. A mixed suspension of endosulfan-hemocyanin conjugate(ES-KLH) 1.1 mg/ml and Freund's adjuvant was injected subcutaneously to white rabbits and then collected antisera were tested for titers by indirect ELISA(1/24,000). Because of difficulties in the synthesis of endosulfan peroxidase conjugate, amine derivative of endosulfan-diol was synthesized and it showed 40% of conjugate yields(2mg/ml of conjugate). the highest sensitivity obtained enzyme-conjugate was a concentration of 200ng/ml. The detection limit of endosulfan in ELISA system was 5 ppb on the standard curve. In application of ELISA for residue analysis, the recoveries were really 100% both in the spiked soil and apple sample regardless of endosulfan concentration treated. On the other hand, chlorinated hydrocarbons of similar structure with endosulfan showed low cross-reactivity$(2.2%{\sim}29.2%).$

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.723-730
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• 2016

Domestic Manila clam production has been reduced due to coastline changes and environmental degradation, but aquaculture industry is facing difficulties caused by an increase in imports. It is important to recognize the integral habitat environment in order to do sustainable aquaculture. The habitat environment of Manila clams (Ruditapes philippinarum) is closely related to the productivity of aquaculture farms. This study investigated 3 indexes, survival (sediment type, hydrodynamic), growth (Chlorophyll a, DIN, DIP) and environment (water temperature, dissolved oxygen, sediment chemical oxygen demand, ignition loss) as indicators of habitat characteristics for a tidal flat farm in Geunso Bay (Pado and Beopsan) from June 2015 to May 2016. As a result, Pado (maximums.; sand 48.76 %, hydrodynamic 10.59 cm/s, Chlorophyll a 12.70 ug/L, exposure time 3 hours, DO 18.65 mg/L) had a higher sand content, faster current speed, more abundant nutrients and DO, providing more favorable conditions for Manila clams than Beopsan (maximums.; sand 37.40 %, hydrodynamic 6.02 cm/s, Chlorophyll a 6.41 ug/L, exposure time 7 hour, DO 14.81 mg/L). In fact, Pado showed a higher density than Beopsan. This study considered the habitat environments of Pado and Beopsan to provide a basis for optimal management practices and potential suitable sites in Geunso bay.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.9
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• pp.521-527
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• 2016

Nanoscale zero valent iron (nZVI) has been intensively studied for the treatment of a plethora of pollutants through reductive reaction, however, the nano size should be of concern when nZVI is considered for water treatment, due to difficulties in recovery. The loss of nZVI causes not only economical loss, but also potential risk to human health and environment. Thus, the immobilization onto coarse or structured support is essential. In this study, two representative processes for nZVI immobilization on granular activated carbon (GAC) were evaluated, and optimized conditions for synthesizing Fe/GAC composite were suggested. Both total iron content and $Fe_0$ content can be significantly affected by preparation processes, therefore, it was important to avoid oxidation during preparation to achieve higher reduction capacity. Synthesis conditions such as reduction time and existence of intermediate drying step were investigated to improve $Fe_0$ content of Fe/GAC composites. The optimal condition was two hours of $NaBH_4$ reduction without intermediate drying process. The prepared Fe/GAC composite showed synergistic effect of the adsorption capability of the GAC and the degradation capability of the nZVI, which make this composite a very effective material for environmental remediation.

• The Korean Journal of Mycology
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• v.25 no.4 s.83
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• pp.330-339
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• 1997

Botrytis cinerea T91-1 has shown to produce at least four different polygalacturonases in a liquid medium containing citrus pectin as a carbon source. One of the enzymes, its molecular weight was estimated as 37 kDa by denatured polyacrylamide gel electrophoresis, was purified by a series of procedures including acetone precipitation, ion exchange, heparin affinity, and reverse phase column chromatographies. By viscometric analysis, the enzyme was revealed as an endo-polygalacturonase. The enzyme activity was inhibited by divalent cations such as $Ca^{2+}$, $Co^{2+}$, and $Cu^{2+}$. Km and Vmax for polygalacturonic acid hydrolysis were 0.33 mg/ml and 28.6 nM/min, respectively. The optimum temperature for enzymatic activity was $55^{\circ}C$ and the enzyme showed optimal pH values between 4.0 and 4.5. The enzyme was stable up to 12 hours in the range of pH 4 to 7 and at the temperature below $30^{\circ}C$. Amino acid sequence from N-terminal up to 6 amino acids determined by Edman degradation showed little homology with polygalacturonases from fungi and plants.

• Korean Journal of Microbiology
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• v.43 no.4
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• pp.273-278
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• 2007

As a model compound of PAHs (polycyclic aromatic hydrocarbons) phenanthrene has been regarded as a toxic material, mutagen and carcinogen in various animals. Biodegradation conditions of phenanthrene such as pH, temperature, shaking speed, stabilizer and cofactor of degrading enzymes were investigated with Trametes versicolor and its transformant T. versicolor MrP1 in YMG medium, minimal medium and soil microcosm. T. versicolor MrP1 can overexpress mrp gene encoding Mn-repressed peroxidase that is involved in fungal degradation. Biodegradations of phenanthrene by T. versicolor and T. versicolor MrP1 were optimally performed in conditions of weak-acid (pH 6.0), $30^{\circ}C$, shaken culture and medium containing 5 mM veratryl alcohol or tryptophan. In these optimal conditions, biodegradation of phenanthrene by T. versicolor MrP1 is 31% higher than that of wild type strain in a minimal medium for 20 days. Biodegradation of phenanthrene by T. versicolor MrP1 was also higher than that of wild type in soil microcosm. T. versicolor MrP1 can be a excellent candidate for the bioremediation of PAHs contaminated environments.