• Journal of Microbiology and Biotechnology
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• 제11권5호
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• pp.804-811
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• 2001

In many Gram-negative bacteria, autoinducers, such as N-acyl-L-homoserine lactone(acyl-HSL) and its derivative molecules, mediate the cell-density-dependnet expression of certain operons. The current study identified the autoinducers produced by Burkholderia cepacia G4, a trichloroethylene-degrading lagoon isolate, using TLC bioassays with Agrobacterium tumefaciens NT1(pDCI141E33) and Chromobacterium violaceum CVO26, and a GC-MS analysis. The ${R_f}\;and\;{R_t}$ values and mass spectra were compared with those of synthetic compounds. Based on the analyses, it was confirmed that G4 produces N-hexanoyl (C6)-, N-octanoyl (C8)-, N-decanoyl (C10)-, N-dodecanoyl (C12)-HSL, and an unknown active species. The integration of the GC peak areas exhibited a ratio of C8-HSL:C10-HSL:C12-HSL at 3:17:1 with C6-HSL and C10-HSL production at trace and micromolar levels, respectively, in the culture supernatants. Nutants partially defective in producing acyl-HSLs were also partially defective in the biosynthesis of an antibiotic substance. These results indicate that the autoinducer-dependent gene regulation in G4 is dissimilar to the clinical B. cepacia strains isolated from patients with cystic fibrosis.

• Journal of Microbiology and Biotechnology
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• 제12권5호
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• pp.849-853
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• 2002

Metal ions have an adverse effect on anaerobic digestion. In an acetate degradation test of upflow of anaerobic sludge blanket granules with $Cu^{2+}$, not all of the acetate that disappeared was stoichiometrically converted to methane. In the presence of 400 mg/g-VSS (volatile suspended solids) $Cu^{2+}$, only 26% of the acetate consumed was converted to methane. To study acetate conversion by other anaerobic microorganisms, sulfate and nitrate reductions were investigated in the presence of $Cu^{2+}$ Sulfate and nitrate reductions exhibited more resistance to $Cu^{2+}$than methanogenesis, and the granules reduced 2.2 mM and 5.4 mM of nitrate and sulfate, respectively, in the presence of 400 mg/g-VSS copper ion. However, the acetate degraded by sulfate and nitrate reductions was only 24% of the missing acetate that could have been stoichiometrically converted to $CO_2$. Accordingly, 76% of the acetate consumed appeared to have been converted to other unknown compounds.

• 한국정보과학회 언어공학연구회:학술대회논문집(한글 및 한국어 정보처리)
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• 한국정보과학회언어공학연구회 2004년도 제16회 한글.언어.인지 한술대회
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• pp.65-72
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• 2004

본 논문에서는 백오프 통계 정보를 이용하여 일반적인 복합명사 뿐만 아니라 외래어 미등록어를 포함한 복합명사도 잘 분해하는 방법을 제안한다. 본 시스템은 입력으로 형태소분석기가 내주는 많은 분석 후보들을 받는다. 단음절 명사를 포함한 분석 후보도 포함되므로 입력 분석 후보의 수는 대단히 많게 된다. 본 모듈의 주요 작업은 이 중에서 가장 좋은 분석후보를 선택하는 것이 된다. 미등록어가 포함된 경우 이에 부합되는 분석 후보를 잘 선택하는 시스템의 개발을 목표로 한다. 이를 위해서 본 시스템에서 사용하는 주요 정보는 단어간 어휘 바이그램 통계정보이다. 또한 외래어 미등록어의 인식 정확성을 높이기 위해 음절 바이그램 정보도 이용한다. 통계정보는 대량의 품사 태깅 말뭉치에서 추출하였다. 데이터 부족 문제를 해소하기 위해서 우리는 백오프(back-off) 평탄화(smoothing) 기법을 이용하였다. 미등록어가 포함된 복합명사의 분석 후보의 수를 줄이기 위한 기술도 연구하였다.

• 약학회지
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• 제26권4호
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• pp.223-229
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• 1982

Uremia is associated with defective protein binding of weakly acidic drugs, whereas the protein binding of basic drugs tends to be normal. The exact chemical nature of compound(s) and mechanism for these changes as yet is unknown, and has not been defined. Organic solvent extraction of pooled normal human urine following hydrolysis by hydrochloric acid produced an extract, which when added to normal human serum, was capable of inducing binding defects similar to those in uremia. Binding defects were observed with the weakly acidic drugs such as nafcillin, salicylate, sulfamethoxazole and phenytoin while the binding of the basic drugs such as trimethoprim and quinidine were unaffected. The binding defects induced by the hydrolyzed urine extract could readily be corrected by same organic solvent extraction of acidified serum and the defects could be transferred to the normal human serum using the organic solvent layer at the physiologic pH (7.4). Followed by reacidification ind extraction of the binding defects induced serum with the same solvent, separated several fractions were obtained on thin-layer chromatography. One of these fractions could reinduce the binding defects and this factor(s) is apparently weakly acidic compounds and tightly bound to serum at physiologic pH, but extractable at acidic pH, and its molecular weight range is approximately 500 or less similar to those seen in uremia. These findings strongly support the hypothesis that the drug binding defect in uremia is due to the accumulation of endogenous metabolic products which arc normally excreted by the kidneys but accumulate in renal failure.

• 대한화학회지
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• 제5권1호
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• pp.9-14
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• 1961

Ethanol extracts of Mung Bean seeds and seedings were analysed by 2-dimensional and circular paper partion chromatography for Nitrogen compounds as a part of the study on the Amino acids metabolism. In the seeds, 18 ninhydrin positive substances were present, before germination, but the number increased to 21 after germination. There were 3 unknown substances and one of it formed newly after germination. After 2-days germination, the amount of amides, such as Asparagine and Glutamine. where increased very large which were very small amount before it. Those were accumulated more in dark place than in light and the amount of Asparigine were more than that of Glutamine. Through the germination, there were large amount of Glutarmic acid, Aspartic acid and Alanine which seems to be concerned in transamination reaction in seedings. Valine, Leucine, and Phenylalanine increased to considerable amount after germination. This is very remarkable fact as those Amino acids were reported to be concerned in transamination reaction recently. ${\gamma}$-amino butyric acid was detected in both Cotyledon and Embroy through the germination. It seemed that there is no any Nitrogen Metabolism in the unbroken seed even if it is preserved very long period.

• 한국분말재료학회지
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• 제28권2호
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• pp.91-96
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• 2021

Rare earth magnets with excellent magnetic properties are indispensable in the electric device, wind turbine, and e-mobility industries. The demand for the development of eco-friendly recycling techniques has increased to realize sustainable green technology, and the supply of rare earth resources, which are critical for the production of permanent magnets, are limited. Liquid metal extraction (LME), which is a type of pyrometallurgical recycling, is known to selectively extract the metal forms of rare earth elements. Although several studies have been carried out on the formation of intermetallic compounds and oxides, the effect of oxide formation on the extraction efficiency in the LME process remains unknown. In this study, microstructural and phase analyses are conducted to confirm the oxidation behavior of magnets pulverized by a jaw crusher. The LME process is performed with pulverized scrap, and extraction percentages are calculated to confirm the effect of the oxide phases on the extraction of Dy during the reaction. During the L ME process, Nd is completely extracted after 6 h, while Dy remains as Dy₂Fe₁₇ and Dy-oxide. Because the decomposition rate of Dy₂Fe₁₇ is faster than the reduction rate of Dy-oxide, the importance of controlling Dy-oxide on Dy extraction is confirmed.

• Journal of Microbiology and Biotechnology
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• 제32권8호
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• pp.982-988
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• 2022

Licorice (Glycyrrhiza) has been used as preventive and therapeutic material for hyperpigmentation disorders. Previously, we isolated noble compounds including dehydroglyasperin C (DGC), dehydroglyasperin D (DGD) and isoangustone A (IAA) from licorice hexane/ethanol extracts. However, their anti-melanogenic effects and underlying molecular mechanisms are unknown. The present study compared effects of DGC, DGD and IAA on pigmentation in melan-a melanocytes and human epidermal melanocytes (HEMn). DGD exerted the most excellent anti-melanogenic effect, followed by DGC and IAA at non-cytotoxic concentrations. In addition, DGD significantly inhibited tyrosinase activity in vitro cell-free system and cell system. Western blot result showed that DGD decreased expression of microphthalmia-associated transcription factor (MITF), tyrosinase and tyrosinase-related protein-1 (TRP-1) in melan-a cells and HEMn cells. DGD induced phosphorylation of MITF, ERK and Akt signal pathway promoting MITF degradation system. However, DGD did not influence p38 and cAMP-dependent protein kinase (PKA)/CREB signal pathway in melan-a cells. These result indicated that DGD inhibited melanogenesis not only direct regulation of tyrosinase but also modulating intracellular signaling related with MITF level. Collectively, these results suggested a protective role for DGD against melanogenesis.

• Journal of Microbiology and Biotechnology
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• 제17권3호
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• pp.496-510
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• 2007

This paper describes the use of a discrete mathematical model to represent the basic mechanisms of regulation of the bacteria E. coli in batch fermentation. The specific phenomena studied were the changes in metabolism and genetic regulation when the bacteria use three different carbon substrates (glucose, glycerol, and acetate). The model correctly predicts the behavior of E. coli vis-a-vis substrate mixtures. In a mixture of glucose, glycerol, and acetate, it prefers glucose, then glycerol, and finally acetate. The model included 67 nodes; 28 were genes, 20 enzymes, and 19 regulators/biochemical compounds. The model represents both the genetic regulation and metabolic networks in an integrated form, which is how they function biologically. This is one of the first attempts to include both of these networks in one model. Previously, discrete mathematical models were used only to describe genetic regulation networks. The study of the network dynamics generated 8 $(2^3)$ fixed points, one for each nutrient configuration (substrate mixture) in the medium. The fixed points of the discrete model reflect the phenotypes described. Gene expression and the patterns of the metabolic fluxes generated are described accurately. The activation of the gene regulation network depends basically on the presence of glucose and glycerol. The model predicts the behavior when mixed carbon sources are utilized as well as when there is no carbon source present. Fictitious jokers (Joker1, Joker2, and Repressor SdhC) had to be created to control 12 genes whose regulation mechanism is unknown, since glycerol and glucose do not act directly on the genes. The approach presented in this paper is particularly useful to investigate potential unknown gene regulation mechanisms; such a novel approach can also be used to describe other gene regulation situations such as the comparison between non-recombinant and recombinant yeast strain, producing recombinant proteins, presently under investigation in our group.

• 한국산림과학회지
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• 제69권1호
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• pp.51-55
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• 1985

Pinus thunbergii를 교배모수(交配母樹)로 하고 대만(台灣)으로부터 도입(導入)된 P. massoniana 화분(花粉)으로 인공교배(人工交配)한 교잡종(交雜種)과 그의 모수(母樹) 풍매차대(風媒次代)들에 대(對)한 충실종자생산(充實種子生産), 생장(生長), 외부형태학적(外部形態學的) 특성(特性) 및 Phenol 물질함량(物質含量)을 조사(調査)하였다. 1) 구과당(毬果當) 충실종자(充實種子) 생산량(生産量)은 교잡종(交雜種)이 평균(平均) 2.3립(粒)으로 풍매(風媒) 26립(粒)에 비(比)하여 저조(低調)하였다. 2) 유묘시(幼苗時) 묘고생장(苗高生長)은 교잡종(交雜種)이 풍매차대(風媒次代)에 비(比)해 평균(平均) 151%로 우수(優秀)하였으며 120~208%의 변이(變異)를 나타냈다. 3) 침엽(針葉)의 외부형태학적(外部形態學的) 특성(特性)은 교잡종(交雜種)이 풍매차대묘(風媒次代苗)에 비(比)하여 침엽(針葉)이 부드럽고, 연(軟)하고, 길며, 연록색(軟綠色)을 나타내고 해부형태(解剖形態)에 있어서는 수지구(樹脂溝)의 위치(位置)가 P. thunbergii 풍매차대(風媒次代)는 중위(中位)인데 비(比)하여 교잡종(交雜種)들은 중위(中位)와 외위(外位)가 동시(同時)에 나타났다. 4) Phenol 물질분석(物質分析)에 있어서는 교잡종(交雜種)과 P. thunbergii 풍매차대간(風媒次代間)에 뚜렷한 차이(差異)가 없었으나 Unknown 4와 6의 물질(物質)이 교잡종(交雜種)에만 나타난 사실(事實)은 특이(特異)하나 이것이 화분수(花粉樹)에서 유래(由來)된 것인지의 여부(與否)는 좀 더 구명(究明)되어야 할 과제(課題)이다.

• Applied Biological Chemistry
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• 제8권
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• pp.11-20
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• 1967

증자대두(蒸煮大豆)에 납두균(納豆菌)(Bacillus subtilis Natto 492-2)을 접종(接種)하고 $38^{\circ}C$에서 발효(醱酵)시키면서 매(每) 10 시간(時間)마다 시료(試料)를 채취(採取) 처리(處理)하여 납두(納豆) 제조과정중(製造過程中)에 일어나는 단백질(蛋白質)의 변화(變化)와 peptide 및 amino acid의 생성양상(生成樣相)에 관(關)하여 다음과 같이 결과(結果)를 얻었다. 1. 증자대두(蒸煮大豆)의 불용성(不溶性) 단백태(蛋白態) 질소(窒素)가 84%에서 발효(醱酵) 50 시간(時間)에 44%로 감소(減少)하였고, 수용성(水溶性) 단백태(蛋白態) 질소(窒素)는 약간(若干)의 증가(增加)를 했지만, peptide, amino acid 및 ammonia 태(態) 질소(窒素)가 8%에서 45%로 증가(增加)하여 단백질(蛋白質)의 가수분해(加水分解)가 현저(顯著)하였다. 2. 납두균(納豆菌)에서 분비(分泌)된 효소(酵素)에 의(依)해 분해(分解)된 peptide 및 amino acid으로 분자사별(分子篩別)한 결과(結果), 대체(大體)로 A.P.L.이 작은 저급(低級) peptide가 많이 생성(生成)됨을 알 수 있으며 발효(醱酵) 30 시간(時間) 이후(以後)에는 이전(以前)보다 단백질(蛋白質) 분해(分解)가 미약(微弱)하게 일어나면서 비교적(比較的) 큰 분자(分子)의 peptide 분해(分解)가 주(主)로 일어나 저급(低級) peptide 및 amino acid 생성(生成)이 많았다. 3. 분자사별(分子篩別)한 X-16 fraction을 시료(試料)로하며 paper chromatography에 의(依)한 amino acid 및 peptide를 동정(同定)한 결과(結果), 16종(種)의 amino acid와 그종(種)의 unknown amino acid가 동정(同定)되었는데, 이들 중(中) phenylalanine은 발효(醱酵) 10 시간(時間) 이후(以後), methionine은 20 시간(時間), proline은 30 시간(時間) 이후(以後)부터 각각(各各) 출현(出現)하였고, 또 Rf치(値)가 다른 3점(點)의 peptide 중(中) 1개(個)는 처음부터 나타나서 발효(醱酵) 20시간이후(時間以後) 소실(消失)하였고, 다른 그점(點)은 20 시간(時間), 40 시간이후(時間以後)부터 각각(各各) 계속(繼續)하여 출현(出現)하였다.