• Applied Biological Chemistry
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• v.44 no.4
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• pp.246-250
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• 2001

In order to produce alkaline protease, psychrotrophic Bacterium which have high enzyme activity, was isolated by using enrichment culture from soil samples and identified as genus Bacillus sp. The optimal pH and temperature for the enzyme activity were pH 6 and $40^{\circ}C$. The temperature range of high enzyme activity was $20{\sim}40^{\circ}C$. The optimal initial pH of culture condition for enzyme was pH 6. The most favorable carbon and nitrogen sources for the production of protease by Bacillus sp. WRD-2 were 3% maltose and 4% yeast extract, respectively.

• The Korean Journal of Zoology
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• v.33 no.3
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• pp.337-345
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• 1990

The properties of three esterases (E2, E6 and E11) which were previously purified from Pieris rapae L. were determined and physiological role of E6 was inferred using immunological methods. Based on inhibitor study, all of the purified esterases were found to be carboxylesterases (EC 3.1.1.1). The Km values for E2, E6 and E11 were determined to be 6.89 X 10-$^4$M. 3.19 $\times$ l0-$^4$M and 3.69 X 10-$^4$M, respectively. The molecular weights of E2, E6 and E11 were estimated to be 42 KD, 81 KD and 174 KD, respectively. The isoelectric points of E2, E6 and E11 were estimated to be pH 5.54, pH 5.89 and pH 6.50, respectively. The concentration of E6 during development was highest at the late 5th instar larval stage and that according to organs at the same stage was highest in midgut. These results suggest that E6 might be a hydrolase involved in the digestion of dietary lipids.

• KSBB Journal
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• v.11 no.6
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• pp.654-662
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• 1996

Bacterial strains which degrade crude oil were isolated by liquid culture from oil-spilled soil, and four isolates were selected among them. The strain Hl7-1 was finally selected after testing emulsifying activity and oil conversion rate. The strain Hl7-1 was identified as a Nocardia sp. based on the test for morphological, biochemical and physiological characteristics. It appears to be highly specialized for growth on crude oil in minimal salts medium since it showed preference for oil or degradation products as substrates for growth. It was found that it could grow on at least fifteen different hydrocarbons. The optimum cultural and environmental conditions were seeked. Cell growth and emulsification activity as a function of time were also determined. Crude oil degradation and the reduction of product peak was identified by the analysis of remnant oil by gas chromatography after 3 days of cultivation. Approximately 83% of oil were converted into a form no longer extractable by organic solvents.

• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.2
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• pp.47-57
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• 2008

Physiological and biochemical changes of five species of genus Quercus exposed to ozone fumigation were investigated to assess their tolerance against ozone toxicity. At the end of 150 ppb ozone fumigation, chlorophyll contents, photosynthetic characteristics, malondialdehyde(MDA) and antioxidative enzyme activities were measured in the leaves of five Quercus species(Quercus acutissima, Q. aliena, Q. palustris, Q. serrata, and Q. variabilis). Chlorophyll and carotenoid contents, net photosynthesis and carboxylation efficiency decreased after ozone treatment, indicating that $O_3$-exposed plants underwent physiological inhibition. The reduction rate of total chlorophyll contents and carboxylation efficiency were respectively 15% and 34% for Q. aliena and 38% and 62% for Q. variabilis. The amount of MDA increased with the highest increase rate of 140% in Q. acutissima which also showed the highest increase rate(60%) of superoxide dismutase(SOD). Ascorbate peroxidase(APX) activity increased in Q. variabilis, Q. serrata and Q. acutissima by ozone treatment. Based on our results, ozone tolerance of the five Quercus species was ranked as Q. aliena>Q. palustris>Q. serrata>Q. variabilis>Q. acutissima. We concluded that chlorophyll contents, photosynthesis, MDA content and antioxidative enzymes were the important physiological markers for tolerance against ozone stress, which were closely related with one another.

• Korean Journal of Veterinary Research
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• v.34 no.3
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• pp.511-516
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• 1994

P multocida was isolated from 80(17.7%) of 450 pneumonic lungs of slaughter pigs. The majority of the biochemical and cultural characteristics of P multocida isolates were identical to those of the reference strains employed. Seventy seven strains(96.3%) among 80 isolates were capsular serotype A while the remaining 3(3.8%) were serotype D. All isolates were very susceptible to ampicillin, ceftiofur, cephalothin, ciprofloxacin and penicillin-G although some of them were resistant to sulfamethoxin and/or streptomycin. Sixty one(76.3%) of all 80 P multocida isolates were dermonecrotic toxin producers. Out of 77 isolates of serotype A and 3 isolates of serotype D, 59(76.6%) and 2(66.7%) were toxigenic, respectively. No difference was noted in dermonecrotic toxigenicity of the isolates in relation to capsular serotypes.

• Korean Journal of Microbiology
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• v.41 no.1
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• pp.74-80
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• 2005

For the reseach of the natural marine antioxidant, an antioxidant-producing bacterium was isolated from seawater in Jeju costal area. The isolated strain SC2-1 was Gram-positive, catalase positive, oxidase negative, motile and small rods. The strain utilized sucrose, dextrose, fructose, mannitol and maltose as a sole carbon and energy source and NaCl required for growth. The radical scavenging activity of the culture supernatant was detemined by DPPH method. This bacterium was identified based on morphological, biochemical characteristics and 16S rDNA sequence analysis, and then was named Exiguobacterium sp. SC2-1. The optimum conditions of culture for production antioxidnat were $25^{\circ}C$, pH 6-8 and $4\%$ NaCl. The stain showed the highest activity and growth cultured in medium which added $1\%$ maltose. Hydroxyl radical activity of the supernatant of Exiguobacterium sp. SC2-1 was $73\%$. The SOD activity of the culture supernatant was estimated about $35\%$.

• Food Industry And Nutrition
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• v.2 no.1
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• pp.7-9
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• 1997

내열설 미생물, Thermus caldophilus CK24에 대한 탄수화물 생합성을 연구하는 과정에서 다양한 탄수화물 관련효소를 탐색하고 그레 대한 생화학적 및 분자생물학적 연구를 수행하고 있다. 일차로 내열성 미생물내 1) 당핵산염 합성효소와 당전이 효소, 2) 탄수화물 대사효소. 3)탄수화물 분해 및 전환효소의 존재를 HPLC/Bio-LC분석을 통하여 확인하고 이들에 대한 연구를 진행하고 있다. 본 연구발표에서는 포도당을 과당으로 전환하는 이성화효소(xylose isomerase), 그리고 맥아당을 트레할로스로 전환하는 트레할로스 합성효소(trehalose synthase)를 소개하고저 한다. 이성화효소는 이미 산업적 과당 생산에서 대규모적으로 사용되고 있는 식품산업효소이다. 본 연구에서는 Thermus caldophilus GK24, Thermus thermophilus HB8, Thermus flavus AT62 3종의 내열성 미생물에 대한 이성화효소 유전자를 클로닝 하고, 각 재조합하고 이성화효소를 대량생산하였다. 이 내열성 이성화효소는 최적 반응 온도가 8$0^{\circ}C$이고, 포도당을 과당으로 전환하는 수유른 55%이었다. 이러한 과당전환률은 이미 산업적으로 사용되고 있는 이성화효소의 과당전환률(43%)보다 훨씬 높은 것으로 과당 생산공정의 단순화의 생산성 향상에 결정적인 요인이라 할 수 있다. 한편 본 이성화효소의 산업적 특성을 증대하기 위하여 구조-기능관계 연구를 착수하였다. 우선 내열성 이산화 효소의 입체 구조를 결정하였고, 구조조정에 따른 기능적 특성을 조사하기 위하여 특정 위치의 선택적 변이 연구를 진행하고 있다. 끝으로 포도당 전이 효소를 추적하던 과정에서 맥아당을 트레할로스로 전환하는 새로운 효소를 Thermus caldo-philus GK24에서 발견하였다. 그 트레할로스 합성효소는 분자량이 약 110kDa이고 최적 반응온도가 75$^{\circ}C$이면, 조효소없이 맥아당을 트레할로스로 80%이상 전환해 주는 가역효소이었다. 본 연구에서는 효소반응의 조건과 특성을 조사하였고, 효소 아미노-밀단의 서열결정정보를 통하여 효소의 유전자를 클로닝 하고 그 유전자의 구조와 발현연구를 진행하고 있다.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2003.04a
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• pp.142-142
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• 2003

본 연구에서는 kiwifruit 과육 속에 들어 있는 단백질분해효소의 gelatin분해활성을 조사하고 그 산업적 방안을 검토하였다. Kiwifruit 과육에서 3개의 단백질분해효소의 활성 밴드(PI, PII, PIII)가 관찰되었다. 단백질분해효소 PI은 220 kD, PII는 51 kD, PIII는 26 kD에 해당하는 것으로 추정할 수 있었다. 이들 단백질분해효소 PI, PII, PIII는 모두 pH 2.0~5.0 범위에서 높은 활성을 보였으며 pH 4.0에서 가장 높게 나타났다. 이들 단백질분해효소 PI, PII, PIII는 모두 cysteine proteinase 저해제인 E-64와 iodoacetate에 의해서 저해되었으며, cysteine proteinase를 촉진하는 DTT, cysteine 및 $\beta$-mercaptoethanol에 의해서 활성이 증가하였다. 그 중 단백질분해효소 PIII는 분자량과 효소의 특성으로 보아 actinidin (EC 3.4.22.14)과 동일한 것으로 판단되었다. 단백질분해효소 PI, PII, PIII는 모두 $Ca^{2+}$, $Mg^{2+}$과 $Mn^{2+}$에 의해 촉진되었으며, $Zn^{2+}$과 Hg$^{2+}$에 의해 완전히 저해되는 것으로 나타났다. 하지만, Co$^{2+}$, Cu$^{2+}$, $Al^{3+}$ , Fe$^{3+}$ 등 금속이온의 영향은 다소 다르게 나타났다. Kiwifruit 과육의 단백질분해효소 PI, PII, PIII 중에서 PI과 PII는 온도가 증가함에 따라 활성이 점차 낮아졌으나 PIII는 비교적 안정한 것으로 조사되었다. 특히, PIII는 5$0^{\circ}C$ 이내의 범위에서 48시간 경과시에도 75% 이상의 활성을 보여 이 범위의 온도에서는 상당 시간 동안 안정한 것으로 나타났다. 단백질분해효소의 산업적 가치를 고려해 볼 때 우선적으로 넓은 기질특이성과 열안정성이 높아야 한다. Kiwifruit에서 추출한 단백질분해효소는 4$0^{\circ}C$ 전후에서 최대의 활성을 보이고, 고온에서도 상당 시간 비교적 안정한 특성을 보여 식품제조, 식육연화 등 식품산업 분야에서의 활용가능성이 높을 것으로 보이며, 나아가 단백질이 갖는 식품학적 기능성을 높이는 데에도 사용할 수 있을 것으로 판단된다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.6
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• pp.801-806
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• 2009

A species producing transglutaminase (EC 2.3.2.13) was isolated from forest soil and identified as Streptomyces platensis YK-2. The transglutaminase was purified from culture broth by 50% methanol precipitation, followed by successive chromatography on DEAE-Sephadex. The yield and purification-fold was 63.4% and 2.2-fold, respectively. The purified microbial transglutaminase (MTG) migrated as a single band of approximately 45 kDa upon sodium dodecyl sulfate polyacrylamide gel eletrophoresis. The isoelectric point determined by multichambered electrofocusing was pH $6.0{\sim}7.0$. The enzyme was strongly inhibited by $Hg^{++}$, but was activated by $Cd^{++}$, $Mg^{++}$, $Mn^{++}$, $Pb^{++}$ and reducing agents such as dithiothreitol and mercaptoethanol.

• Journal of Life Science
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• v.13 no.4
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• pp.535-540
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• 2003

The antagonistic microorganisms against Streptococcus sanguis, S. salivarius and S. mutans causing the dental caries of oral diseases were isolated from Korean traditional soy sauce. Twenty five strains were isolated by pairing culture, paper disc culture and dual culture methods. The isolate NG 06 strain was observed with various cultural and physiological test, and $Biolog^{(R)}$ Bacterial Identification System. The strain was identified as Bacillus racemilacticus. The isolate NG 16 strain was confirmed to Gram-positive, rods, endospore production, utilization of melibiose, casein hydrolysis and starch hydrolysis. Also the second strain NG 16 was identified as $\beta$. amyloliquefaciens.