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Small-Scale Pond Effects on Reducing Pollutants Load from a Paddy Field (논의 양분유출 저감을 위한 저류지 효과)

  • Kim, Min-Kyeong;Kwon, Soon-Ik;Jung, Goo-Bok;Hong, Seong-Chang;Chae, Mi-Jin;Yun, Sun-Gang;So, Kyu-Ho
    • Korean Journal of Environmental Agriculture
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    • v.32 no.4
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    • pp.355-358
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    • 2013
  • BACKGROUND: Water-born pollution loads by agricultural non-point source (NPS) pollution are expected to become intensified due to ongoing precipitation change. Therefore, it is essential to develop a best management practice (BMP) that is suitable to agricultural environments in Korea. This study aimed to develop an environmental-friendly BMP to reduce NPS pollution load by agricultural activities. An eco-friendly way, small drainage pond, was suggested in this study to avoid direct drainage of agricultural runoffs and eventually reduce the amount of pollutants discharged into the surrounding aqua-environment. METHODS AND RESULTS: A small pond ($12m^2$) was constructed at the corner of a rice paddy field ($1,715m^2$) located in Suwon, Korea. Water was allowed to drain only via a small drainage pond. Sampling was repeatedly made at two locations, one from an entrance and the other from an exit of a pond, during the rice cultivation period (May to October, 2012). Generally, sampling was made only when runoff water drained through a pond, such as during and/or after rain (irrigation). The water quality analysis showed that all quality parameters (SS, $COD_{Mn}$, T-N, and T-P) were improved as water passed through the pond. The amount of runoff water was reduced by 96~100%. Suspended solids and COD concentrations was reduced by 79.3% and 45.6%, respectively. In case of T-N and T-P concentrations, the reduction rates were 52.2% and 60.5%, respectively and the amount of T-N and T-P were reduced by 16.3~73.0% and 15.4~70.1%, respectively. CONCLUSION(S): Our data implies that agricultural NPS pollution from rice paddy fields can be effectively managed when an appropriate drainage water management practice is imposed. In this paper, it was suggested that an installation of a small drainage pond can be effective to prevent not only the nutrient loss from rice fields but also pollutant discharge to surrounding water environments.

Study on the Change of Nutrients Contents according to the Use of various Multi-Functional Grinder (믹서의 종류에 따른 영양소 함량 변화에 대한 연구)

  • Choi, Byung Bum;Kim, Chun Huem;Kim, Young Soon
    • Culinary science and hospitality research
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    • v.20 no.6
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    • pp.262-274
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    • 2014
  • In this study, changes of nutrients such as vitamins, minerals, and antioxidants were determined by using a multi-functional grinder. Contents of vitamin C and vitamin $B_1$ were measured by HPLC, and antioxidant activity was estimated toward free radical scavenging effect in using DPPH. Contents of minerals(Zn, Mn, Fe, Mg, K, and Ca) were computed by ICP-Mass. Results identified that the contents of vitamin C was $44.06{\pm}10.86mg/kg$ in mandarine, $132.1{\pm}22.80mg/kg$ in orange, and $12.79{\pm}2.01mg/kg$ in pineapple by using the hand blender for 3 minutes, and the loss rate of vitamin C contents were 12%, 7%, and 12% in comparison with the control group. In addition, the contents of vitamin C were $41.89{\pm}5.55mg/kg$ in mandarine, $131.51{\pm}12.67mg/kg$ in orange and $16.76{\pm}1.47mg/kg$ in pineapple when using of the grinder for 3 minutes, and the loss rate of vitamin C contents were 16%, 8%, and 17%. The results of vitamin $B_1$ showed a tendency to decrease in the same manner as the content of vitamin C even if there was no significant difference. Furthermore, the result of antioxidant activity revealed that free radical scavenging effect of sample was 60% decreased when using a hand blender and 10% decreased when using a grinder. Thus decrease rate of antioxidant activity when using the hand blender was higher than grinder. Lastly, current study could find any significant differences among the 16 food samples for cooking when employing the multi-functional grinder(p<0.05).

Effect of SipJeonDaeBo-Decoction on Target Organ Metal Level in Rats (십전대보탕을 투여한 흰쥐의 중요장기중 금속농도변화에 대한 연구)

  • Yoon Seong-Wook;Lee Sun-Dong
    • Journal of Society of Preventive Korean Medicine
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    • v.4 no.1
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    • pp.51-69
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    • 2000
  • This dissertation was to research how some metal level within SipJeonDaeBo - Decoction, one of oriental prescriptions, influence Sprague-Dawley animals. 1. Under the experiment with drinking waters there was no metal ${\sim}0.65\;mg/L$ detected. A metal with feed found 0.001-376.983mg/kg. 2. In the mice's kidney, brain, bones used experiment, As searched 0.474 mg/kg, 0.486 mg/kg, 0.314 mg/kg 0.834 mg/kg respectively ; Cd 0.060 mg/kg, 0.045 mg/kg, 0.030 mg/kg, 0.353 mg/kg, ; Co 0.105 mg/kg, 0.063 mg/kg, 0.030 mg/kg, 0.399 mg/kg, ; Cr 0.292 mg/kg, 0.304 mg/kg, 0.234 mg/kg, 0.962 mg/kg, ; Cu 4.201 mg/kg, 3.759 mg/kg, 1.923 mg/kg, 0.484 mg/kg, ; Fe 57.535 mg/kg, 150.571 mg/kg, 17.178 mg/kg, 281.506 mg/kg, ; no Hg, Mn 0.612 mg/kg, 2.968 mg/kg, 0.528 mg/kg, 4.205 mg/kg, ; Ni 0.094 mg/kg, 0.072 mg/kg, 0.078 mg/kg, 27.714 mg/kg, ; Pb 0.269 mg/kg, 0.293 mg/kg, 0.283 mg/kg, 43.142 mg/kg ; Zn 4.149 mg/kg, 21.861 mg/kg, 8.088 mg/kg, 226.283 mg/kg respectively. 3. In level of hazardous metal within idney control group searched 0.194 {\pm}\; 0.052 mg/kg, experimental I g개up $0.189{\pm}0.036\;mg/kg$, experimental I group $0.264 {\pm}{\pm}\;0.179\;mg/kg$. In level of non hazardous metal control group searched $15.917{\pm}5.575\;mg/kg$, experiment I group $17.064{\pm}2.246\;mg/kg$, experiment II group $16.892{\pm}3.586\;mg/kg$. Besides in total level of metal control g.cup detected $6.484{\pm}2.258\;mg/kg$, experiment I group $6.940{\pm}0.914\;mg/kg$, experiment II group $6.915{\pm} 1.508\;mg/kg$ There all was no statistical significance. 4. In level of hazardous metal within the liver control group searched $0.187{\pm}0.048\;mg/kg$, experiment I g개up $0.168[\pm}0.079\;mg/kg$, experiment II group $0.277{\pm}0.159\;mg/kg$. In level of non hazardous heavy metal control group detected $44.925{\pm}18.468\;mg/kg$, experiment I group $39.917{\pm}12.772\;mg/kg$, experiment II group $49.525{\pm}33.484\;mg/kg$. Besides in total concentration control group searched $18.082{\pm}7.395\;mg/kg$, experiment I group $16.068{\pm}5.128\;mg/kg$, experiment II group $19.977{\pm}13.443\;mg/kg$. There was no statistical significance but hazardous metal gets more level in the experilnent group than in the control group. 5. In level of hazardous metal within brain control group searched $0.145{\pm}0.056\;mg/kg$, experiment I group $$0.167{\pm}0.030\;mg/kg, erperiment II group $0.172{\pm}0.123\;mg/kg$. In level of non hazardous heavy metal control group detected $6.488{\pm}0.965\;mg/kg$, experiment I group $7.290{\pm}0.588\;mg/kg$, experiment II group $7.010{\pm}1.627\;mg/kg$. Besides in total concentration control group searched $2.683{\pm}7.395\;mg/kg$, experiment I group $3.017{\pm}0.238\;mg/kg$, experiment II group $2.908 {\pm} 0.711\;mg/kg$. Therefore there was no statistical significance. 6. In level of hazardous metal within bone control group searched $8.172{\pm}5.195 \;mg/kg$, experiment I group $9.128{\pm}4.143\;mg/kg$, experiment II group $9.401{\pm}6.924\;mg/kg$. There is statistical significance(p<0.05). In level of non hazardous metal control group detected $94.065{\pm}36.035\;mg/kg$, experiment I group $147.563 {\pm}79.939\;mg/kg$, experiment II group $142.730{\pm}77.374\;mg/kg$. Besides in total level control group searched $48.530{\pm}16.523\;mg/kg$, experiment I group $64.502{\pm}31.078\;mg/kg$, experiment II group $62.733 {\pm}34.641\;mg/kg$. Therefore there was no statistical significance. 7 In the correlative research as to how each metal influences to ingestion Cd and Co searched 0.954 and Pb and Ni -0.0884 from kidney. Co and Cd was 0.995 and Zn and As -0.190 from liver. Co and Cd were 0.995 and Zn and Cu -0.393 from brain. Co and Cd were 0.998 and Zn and Mn -0.206 from bones

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Factor Analysis of Soil and Water Quality Indicators in Different Agricultural Areas of the Han River Basins (한강수계 농업지대에서 토양과 수질 지표에 대한 요인 분석)

  • Jung, Yeong-Sang;Yang, Jae-E;Joo, Jin-Ho;Kim, Jeong-Je;Kim, Hyun-Jeong;Ha, Sang-Keun
    • Korean Journal of Soil Science and Fertilizer
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    • v.32 no.4
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    • pp.398-404
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    • 1999
  • Factor analysis technique was employed to screen the principal indicators influencing soil and water qualities in the intensively cultivated areas of the Han River Basin. Soil chemical parameters were analyzed for the soil samples collected at intensive farming area in Pyungchang-Gun, and water quality monitoring data were obtained from the agricultural small catchments of Han River Basin during 1996 and 1997. Among the $11{\times}11$ cross correlation matrix, 29 correlations were significant out of 55 soil quality indicator pairs. The overall Kaiser's measure of sampling adequacy(KMS) value was acceptable with 0.60. Most indicators except iron were acceptable. Among soil indicators, the first factors showing high factor loadings were pH, Ca and Mg. The factor loading was the highest for Ca. The second factor could be characterized as phosphate and micronutrient. The third factor was organic matter and EC, and the fourth factor was potassium and Fe. Out of 190 water quality indicators, 86 correlations were significant. Overall KMS value was 0.74, but the KMS values for pH, TSS, Cd, Cu and Fe were lower than 50. The first factor of EC accounts 27.1 percents of the total variance, and showed high factor loadings with Na, Ca, $SO_4$, Mg, K, Cl, $NO_3$, and T-N. The second factor showed high loadings with Zn, Fe, Mn and Cd. The third to seventh factors could be characterized as $PO_4$, TSS, inorganic nitrogen, pH and T-P, and Cu factors, respectively. The factor score for EC was the highest in Kuri, followed by Chunchon, Dunnae and Daegwanryng. The factor score for heavy metals were the highest in the Daegwanryng. The results demonstrated that the factor analysis could be useful to select the most principal factor influencing soil and water qualities in the agricultural watershed.

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The effect of ceramic thickness and number of firings on the color of a zirconium oxide based all ceramic system fabricated using CAD/CAM technology

  • Bachhav, Vinay Chila;Aras, Meena Ajay
    • The Journal of Advanced Prosthodontics
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    • v.3 no.2
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    • pp.57-62
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    • 2011
  • MATERIALS AND METHODS. Ceramics have a long history in fixed prosthodontics for achieving optimal esthetics and various materials have been used to improve ceramic core strength. However, there is a lack of information on how color is affected by fabrication procedure. The purpose of this study was to evaluate the effects of various dentin ceramic thicknesses and repeated firings on the color of zirconium oxide all-ceramic system (LavaTM) fabricated using CAD/CAM technology. MATERIALS AND METHODS. Thirty disc-shaped cores, 12 mm in diameter with a 1 mm thickness were fabricated from zirconium oxide based all ceramic systems ($Lava^{TM}$, 3M ESPE, St Paul, MN, USA) and divided into three groups (n = 10) according to veneering with dentin ceramic thicknesses: as 0.5, 1, or 1.5 mm. Repeated firings (3, 5, 7, or 9) were performed, and the color of the specimens was compared with the color after the initial firing. Color differences among ceramic specimens were measured using a spectrophotometer (VITA Easyshade, VITA Zahnfabrik, Bad $S{\ddot{a}}ckingen$, Germany) and data were expressed in CIELAB system coordinates. A repeated measures ANOVA and Bonferroni post hoc test were used to analyze the data (n = 10, ${\alpha}=.05$). RESULTS. $L^{\ast}a^{\ast}b^{\ast}$ values of the ceramic systems were affected by the number of firings (3, 5, 7, or 9 firings) (P<.001) and ceramic thickness (0.5, 1, or 1.5 mm) (P<.001). Significant interactions were present in $L^{\ast}a^{\ast}b^{\ast}$ values between the number of firings and ceramic thickness (P<.001). An increase in number of firings resulted in significant increase in $L^{\ast}$ values for both 0.5 mm and 1.5 mm thicknesses (P<.01, P=.013); however it decreased for 1 mm thickness (P<.01). The $a^{\ast}$ values increased for 1 mm and 1.5 mm thicknesses (P<.01), while it decreased for 0.5 mm specimens. The $b^{\ast}$ values increased significantly for all thicknesses (P<.01, P=.022). As the dentin ceramic thickness increased, significant reductions in $L^{\ast}$ values (P<.01) were recorded. There were significant increases in both $a^{\ast}$ and $b^{\ast}$ values (P<.01) as the dentin ceramic thickness increased. CONCLUSION. The number of firings and dentin ceramic thickness have a definite effect on the final color of all ceramic system tested. The mean ${\Delta}E$ value increased as the dentin ceramic thicknesses increased for zirconium-oxide based all ceramic specimens tested. However, the mean ${\Delta}E$ values were less than 3.7${\Delta}E$ units which is rated as a match in the oral environment.

Chemical Components and Physiological Activities of Bamboo (Phyllostachys bambusoides Starf) Extracts Prepared with Different Methods (추출방법에 따른 대나무(왕대) 추출물의 화학성분 및 생리활성)

  • Ju, In-Ok;Jung, Gi-Tai;Ryu, Jeong;Choi, Joung-Sik;Choi, Yeong-Geun
    • Korean Journal of Food Science and Technology
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    • v.37 no.4
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    • pp.542-548
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    • 2005
  • Chemical components and physiological activities Bamboo (Phyllostachys bambusoides Starf) extracts obtained by burning, dry heating or extracting with water or 70% ethanol and were investigated. Contents of soluble solid and total phenolic compounds were highest in the ethanol extract. Contents of polyphenols such as catechin, chlorogenic acid, caffeic acid, 3-hydroxy benzoic acid and ferulic acid were determined. Free sugars consisted of galactose, glucose, fructose, and sucrose. Organic acids including citric, tartaric, malic, succinic, and acetic acid were present in the bamboo extracts. Antioxidant activities of dry heat and ethanol extracts were higher than those of BHA or ${\delta}-tocopherol$. Nitrite- scavenging effect of extracts ranged from 84.7 to 99.6% at pH 1.2 ana 3.0. Tyrosinase-inhibitory activity was higher in the water extract, and SOD-like and ACE-inhibitory activity were highest in tile dry kent extract. Antimicrobial activities of the bamboo extracts were strong against Bacillus subtilis, Escherichia coli O157, and Staphylococcus aureus.

Environmental Geochemistry and Heavy Matel Contamination of Ground and Surface Water, Soil and Sediment at the Kongjujuil Mine Creek, Korea (공주제일광산 수계에 분포하는 지하수, 지표수, 토양 및 퇴적물의 환경지구화학적 특성과 중금속 오염)

  • 이찬희
    • Economic and Environmental Geology
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    • v.32 no.6
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    • pp.611-631
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    • 1999
  • Enviromental geochemisty and heary metal contamination at the Kongjueil mine creek were underaken on the basis of physicohemical properties and mineralogy for various kinds of water (surface, mine and ground water),soil, precipitate and sediment collected of April and December in 1998. Hydrgeochemical composition of the water samples are characterized by relatively significant enricant of Ca+Na, alkiali ions $NO_3$ and Cl inground and surfore water, wheras the mine waters are relatively eneripheral water of the mining creek have the characteristics of the (Ca+Mg)-$(HCO_3+SO_4)$type. The pH of the mine water is high acidity (3.24)and high EC (613$\mu$S/cm)compared with those of surface and ground water. The range of $\delta$D and $\delta^{18}O$ values (relative to SMOW) in the waters are shpwn in -50.2 to -61.6% and -7.0 to -8.6$\textperthousand$(d value=5.8 to 8.7). Using computer program, saturation index of albite, calcite, dolomite in mine water are nearly saturated. The gibbiste, kaolinite and smectite are superaturated in the surface and ground water, respectively. Calculated water-mineral reaction and stabilities suggest that weathing of silicate minerals may be stable kaolinite owing to the continuous water-rock reaction. Geochemical modeling showed that mostly toxic heavy metals may exist larfely in the from of metal-sulfate $(MSO_4\;^2)$and free metal $(M^{2+})$ in nmine water. These metals in the ground and surface water could be formed of $CO_3$ and OH complex ions. The average enrichment indices of water samples are 2.72 of the groundwater, 2.26 of the surface water and 14.15 of the acid mine water, normalizing by surface water composition at the non-mining creek, repectively. Characteristics of some major, minor and rate earth elements (Al/Na, K/Na, V/Ni, Cr/V, Ni/Co, La/Ce, Th/Yb, $La_N/Yb_N$, Co/Th, La/Sc and Sc/Th) in soil and sediment are revealed a narrow range and homogeneous compositions may be explained by acidic to intermediate igneous rocks. And these suggested that sediment source of host granitic gneiss colud be due to rocks of high grade metamorphism originated by sedimentary rocks. Maximum concentrations of environmentally toxic elements in sediment and soil are Fe=53.80 wt.% As=660, Cd=4, Cr=175, Cu=158, Mn=1010, Pb=2933, Sb=4 and Zn=3740 ppm, and extremely high concentrations are found are found in the subsurface soil near the ore dump and precipitates. Normalizing by composition of host granitic gneiss, the average enerichment indices are 3.72 of the sediments, 3.48 of the soils, 10.40 of the precipitates of acid mine drainage and 6.25 of the soils near the main adit. The level of enerichment was very severe in mining drainage sediments, while it was not so great in the soils. mineral composition of soil and sediment near the mining area were partly variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. reddish variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. Reddish brown precipitation mineral in the acid mine drainage identifies by schwertmanite. From the separated mineralgy, soil and sediment are composed of some pyrite, arsenopyite, chalcopyrite, sphalerite, galena, malachite, goethite and various kinds of hydroxied minerals.

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Activities of the Hydrolytic Enzymes Produced by Plant Pathogenic Fungi, Sclerotium rolfsii, Sclerotinia Sclerotinia and Sclerotiorum, and Helminthosporium sigmoideum var. irregulare (수종의 식물병원균(흰비단병균$\cdot$균핵병균 및 좀검은 균핵병균)이 생산하는 가수분해효소의 활성)

  • Cho B. H.;Kim K.
    • Korean journal of applied entomology
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    • v.16 no.4 s.33
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    • pp.199-208
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    • 1977
  • Activities of various hydrolytic enzymes produced by three plant pathogenic fungi, Sclerotium rolfsii Sacc., Sclerotinia sclerotiorum (Lieb.) deBary and Helminthosporium sigmoideum var. irregulare Crallery et Tullius, were measured. Activties and amounts of the enzymes in mycelia, cultural filtrates, and sclerotia(except of sclerotia of H. sigmoideum var. irregulare) were estimated at various pH levels in order to find out optimal pH for their enzymatic activities. Enzymes such as cellulase (ex), invertase, xylanase, $\beta-amylase$, polymethylgalacturonase, polygalacturonase, phosphatase and protease were estimated. Culture solution for production of enzymes was prepared by adding of 10g, D-glucose, 1.3g $NH_4NO_3,\; 0.5g\; MgSO_4,\;7H_2O,\; and\; 1.0g\; KH_2PO_4$ into 1 liter of potato decoction plus 2ml of micro element solution consisting of 0.2mg. Fe, 0.2mg Zn, and 0.1mg Mn as the sulphates into 1 liter of distilled water. All tested mycelia and cultural filtrates were obtained from the cultures incubarted in previous solution for ten days at $25^{\circ}C$, and sclerotia were harvested from PDA plates of 3. days old, The crude enzyme solutions were prepared according to the method of Miyazaki etal. Ten days after incubation, activities of Cx produced by Scl. sclerotiorum were higher than those of the other fung and each of Cx from three fungi showed different pH optima, such as S. rolfsii and Scl. schlerotiorum in acid side (around pH 3.0), H. sigmoideum var. irregulare in neutral side (around pH 6.3). Invertase activities of S. rolfsii were 20 times higher than those of the other fungi in all samples. All tested fungi, however, showed no significant difference between the enzymatic activities of their cultural filtrate and mycelia and the activities in sclerotia of S. rolfsii and Scl. sclerotiorum were hardly recognized. There were multiple peaks on the xylanase activity curves of three fungi in terms of pH values. High activities of the xylanase were revealed in sclerotia of S. rolfsii and Scl. sclerotiorum, and in mycelia of H. sigmoideum var. irregulare. The highest activities of $\beta-amylase$ were shown both in mycelia and cultural filtrate of H. sigmoideum var. irregulae among the tested fungi, and their optimal pH was 6.2 in both mycelia and cultural filtrate. In the S. rofsii and Sel. sclerotiorum, however, the activities of cultural filtrates were higher than those of the other fungi, and optimal pH was 3.0 and 6.2 for cultural filtrate and both mycelia and sclerotia, respectively. Activities of PMG were high in cultural filtrates of all tested fungi, especially in Scl. sclerotiorum and H. sigmoideum var. irregulare. Mycelia of themalso showed the considerable activities. Optimal pH for enzymatic activities were variable with thekind of fungi or with the samples measured. The highest activities of PG were presented by mycelia of S. rolfsii and Scl. sclerotiorum. $9.l\mu /min.\; and\; 9.5\mu g/min.$, respectively. Optimal pH for activity of PG in mycelia was around 4.5 in S. rolfsii and around 3.0 in Scl. sclerotiorum. Phosphatase of S. rolfsii and Scl. sclerotiorum was more active in acid side (optimal PH3. 5) and that of H. sigmoideum var. irregulare showed one peak each in acid, neutral and alkaline side. But the highest peak was at pH 9.5. Protease of all tested fungi was more active at pH 10.0, especially that of the cultural filtrate of H. sigmoideum var. irregualre.

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Dihydroxy-acid Dehydratase Involved in the Biosynthesis of the Branched-Chain Amino acids, Isoleucine and Valine, from the archaeon Sulfolobus solfataricus

  • Kim, Seong-Hun;Lee, Sun-Bok
    • 한국생물공학회:학술대회논문집
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    • 2005.04a
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    • pp.327-333
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    • 2005
  • Dihydroxy-acid dehydratase (DHAD, 2,3-dihydroxy-acid hydrolyase, EC 4.2.1.9) is one of the key enzymes involved in the biosynthetic pathway of the branched chain amino acid isoleucine and valine. Although the enzyme have been purified and characterized in various mesophiles including bacteria and eukarya, the biochemical properties of DHAD has bee not yet reported from hyperthermophilic archaea. In this study, we cloned, expressed, and purified a DHAD homologue from the thermoacidophilic archaeon Sulfolobus solfataricus P2, which grows optimally at $80\;^{\circ}C$ and pH 3, in E. coli. Characterization of the recombinant S. solfataricus DHAD (rSso_DHAD) revealed that it is the dimeric protein with a subunit molecular weight of 64,000 Da in native structure. rDHAD showed the highest activity toward 2,3-dihydroxyisovaleric acid among 17 aldonic acid substrates Interestingly, this enzyme also displayed 50 % activities toward some pentonic acids and hexonic acids when compared with the activity of this enzyme to the natural substrate. Moreover, rSso_DHAD indicated relatively higher activity toward D-gluconate than any other hexonic acids tested in substrates. $K_m$ and $V_{max}$ values of rSso_DHAD were calculated as $0.54\;{\pm}\;0.04\;mM$ toward 2,3dihydroxyisovalerate and $2.42\;{\pm}\;0.19\;mM$ toward D-gluconate, and as $21.6\;{\pm}\;0.4\;U/mg$ toward 2,3-dihydroxyisovalerate and $13.8\;{\pm}\;0.4\;U/mg$ toward D-gluconate, respectively. In the study for biochemical properties, the enzyme shows maximal activity between $70^{\circ}C$ and $80^{\circ}C$, and the pH range of pH 7.5 to 8.5. The half life time at $80^{\circ}C$ was 30 min. A divalent metal ion, $Mn^{2+}$, was only powerful activators, whereas other metal ions made the enzyme activity reduced. $Hg^{2+}$, organic mercury, and EDTA also strongly inhibited enzyme activities. Particularly, the rSso_DHAD activity was very stable under aerobic condition although the counterparts reported from mesophiles had been deactivated by oxygen.

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Synergistic Effect of Grapefruit Seed Extract, EDTA and Heat on Inactivation of Bacillus cereus Spore (자몽종자추출물, EDTA와 열 병행에 의한 Bacillus cereus 포자 불활성화 상승효과)

  • Yang, Seung-Kuk;Kim, Jung-Jee;Kim, Seok-Joong;Oh, Se-Wook
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.40 no.10
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    • pp.1469-1473
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    • 2011
  • The efficacy of antimicrobial agents and heat treatments on spore inactivation was investigated. Grapefruit seed extract (GFE) and ethylenediaminetetraacetic acid (EDTA) were used and as antimicrobial agents, and heat treatments were conducted at $70^{\circ}C$, $80^{\circ}C$, and $90^{\circ}C$ for 30 minutes. Heat treatments at $90^{\circ}C$ were the most effective on spore inactivation as a single treatment and caused a 2.3 log reduction. When combined with a single treatment to discover synergistic effects, 1% GFE with $80^{\circ}C$ heat treatments and 0.5 mM EDTA with $80^{\circ}C$ heat treatments resulted in 2.1 log and 3.2 log reductions, respectively, though they did not show reductions at each single treatment (GFE 1% (v/v), EDTA 0.5 mM, $80^{\circ}C$). So it was concluded that by combining GFE, EDTA in low concentration treatment, and heat treatment, B. cereus spores can be effectively inactivated.