• 한국미생물·생명공학회지
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• 제19권2호
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• pp.116-121
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• 1991

A bacterial strain KN, which highly produced a protease, was isolated from several soil samples and identified to to belong to the genus Bacillus. We selected mutant strain Bacillus sp. KN103N, which was hyperproducer of protease and was resistant to D-cyclowerine, from the strain KN by several steps of mutagenesis. Neutral protease productivity of mutant strain KN103N was about 55 times as much as that of the original strain KN. The optimum pH and temperature for the enzyme activity were 7.0 and 50$^{\circ}C$, respectively and the enzyme was relatively stable at pH6.0~8.0 and below 40$^{\circ}C$. The enzyme was inactivated by EDTA, but not by DFP. These results indicate that the enzyme from Bacillus sp. KN103N was a neutral (metallo-) protease.

• Clinical and Experimental Pediatrics
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• 제50권9호
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• pp.823-834
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• 2007

Interferon (IFN) alpha has been the first line therapy of chronic hepatitis B in children, but HBeAg seroconversion occurred in 26% of treated children compared to 11% of controls in multinational randomized controlled study. Recently, lamivudine was shown to be a potent inhibitor of Hepatitis B virus (HBV) reproduction both in HBeAg positive and in HBeAg negative (the pre-core mutant form) chronic hepatitis in randomized studies worldwide. Lamivudine therapy led to considerable improvement in the seroconversion rate of HBeAg in children with chronic hepatitis B, though long-term therapy resulted in the expansion of lamivudine-resistant mutant viruses. Combination therapy with lamivudine plus alpha-IFN does not seem to improve HBe Ag seroconversion. Above all, the most effective way to prevent hepatitis B is universal HBV vaccination.

• 약학회지
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• 제35권2호
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• pp.111-118
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• 1991

A comparative study was performed on two different strains of Leishmania major, chloroquine sensitive strains (Chl$^{S}$) and its mutant chloroquine resistant strains (Chl$^{R}$). Chl$^{R}$ strains were obtained at 5$\times$$10^{-4}$M chloroquine. Remarkable differences were observed at the initial chloroquine uptake in Chl$^{R}$ and Chl$^{S}$, i.e., the rate of uptake was very reduced in Chl$^{R}$ (Km values were 70 nM and 125 nM, respectively). Influx and accumulation of chloroquine were also compared between wild type and mutant. An increasing tendency in both influx and accumulation of chloroquine was shown in Chl$^{S}$, but Chl$^{R}$ demonstrated a rapid release after a little uptake (influx) at the early stage. This result is thought to be basis of their resistance for Chl$^{R}$ strains.

• 방사선산업학회지
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• 제4권3호
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• pp.247-252
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• 2010

The present study has been performed to select the osmotic tolerant lines using polyethylene glycol (PEG 6000) through an in vitro and in vivo mutagensis with a gamma-ray. During the screening, we selected three mutant lines that seemed to confer elevated osmotic tolerance in high concentrations of PEG 6000. Fruits of these mutants (Os-HK101, Os-HK102 and Os-HK103) were increased to sugar concentration, L-glutamine acid, vitamin C content and lycopine content than those of the wild type. Also the chlorophyll contents were few decreased more in the three mutant lines than the WT plants. Our results suggest that the Os-HK101 is characterized as osmotic stress tolerance considering the sugar concentration and lycopine content. It is expected that the result of this study can be used for breeding more competitive species with respect to contents in sugar or functional chemicals from the selected osmotic resistant lines.

• 한국환경보건학회지
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• 제31권5호
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• pp.360-364
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• 2005

Streptomyces fradiae로부터 Tylosin을 효율적으로 생산하기 위해 지방산 내성균주을 분리 했다. 여러 지방산중에서 oleic acid 1.6 g/l 이상이 첨가될 때 세포 성장이 완전히 저해 되었다. 그러나 oleic arid 1.2 g/l에서 얻어진 TM-224-1 균주는 최대 균체농도와 tylosin 생산이 얻어졌다. 또한 oleic acid 소비속도는 parent strain 비해 3.8배 증가했다. Oleic acid 내성균주, TM-224-1 균주와 parent strain을 이용해서 jar fermentor에서 균체농도, tylosin 생산, 그리고 rapeseed oil 소비를 표준조건하에 5일동안 비교하였다. TM-224-1 균주을 이용할 경우 균체 농도는 초기에 parent strain비해 증가했으나 배양중반부터는 감소하기 시작했다. rapeseed oil 소비의 경우는 거의 비슷했다. 그러나 Tylosin 생산 수율은 parent strain 비해 약 3.2배 증가했다.

• KSBB Journal
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• 제21권4호
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• pp.286-291
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• 2006

본 연구에서는 적효모 X. dendrorhous KCTC 7704로부터 여러 ${\beta}$-ionone 내성 변이균주를 선별하였다. 야생균 KCTC 7704는 ${\beta}$-ionone 0.021 mM 농도에서 생육이 현저히 저하되었지만, NTG처리 후 ${\beta}$-ionone 0.1 mM 농도에서 선별된 변이균주는 ${\beta}$-ionone 0.15 mM에서도 70% 이상의 상대 생육율을 나타내는 매우 강한 ${\beta}$-ionone 내성을 갖고 있었다. 여러 ${\beta}$-ionone 농도에서 선별한 변이균주들을 $20^{\circ}C$에서 4일간 회분식 발효로 배양하여 그 특성을 조사하였다. 선별된 가장 우수한 변이균주는 야생균주보다 카로티노이드 생성능이 2.3배 향상(즉 $1.2{\mu}g$ of total carotenoids per mg of dry cells)되었으며 유기산과 같은 대사산물은 거의 생성하지 않았다. 여러 탄소원 들에 대한 비교 발효특성 연구 결과 과당이나 자당을 사용했을 때봐 비교하여 포도당 배지에서 최종 균체농도 및 총 카로티노이드 생성량이 많았다. 포도당이 제한되는 연속발효(dilution rate $0.04h^{-1}$) 실험을 통하여 pH의 영향을 조사한 결과 균체농도 및 총 카로티노이드 생성은 pH 4.0 조건하에서 최적인 것을 알 수 있었다.

• 한국미생물·생명공학회지
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• 제19권6호
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• pp.583-587
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• 1991

대장균 W3110으로부터 NTG 및 UV를 사용하여 여러 단계의 돌연변이 실험을 거치면서 스레오닌 고생산균주인 대장균 TF427를 선별하였다. 선별된 변이주는 스레오닌 유사체인 AHV 내성, 메치오닌 및 이소루이신 요구성을 특징으로 한다. 5-L 발효조 실험에서 44시간 발효하였을 때 46.5g/l의 스레오닌이 생산되었다. 효모분석에 의하면, TF427의 아스파토키나아제 I의 활성은 스레오닌에 의해 저해받지 않았으며, 이 효소의 합성은 스레오닌과 이소루이신에 의해 억제를 받지 않았다.

• 한국약용작물학회지
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• 제10권4호
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• pp.273-276
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• 2002

Rehmannia glutinosa is one of the most important medicinal crops in Korea. However, various plant pathogens including Fusarium sp. cause great damages and cause enormous economic losses. Therefore, this study was conducted to select Fusarium resistant plants by using mutagen-treated Rehmannia glutinosa. The plant material used was a native accession of Rehmannia glutinosa. As a result, among the Rehmannia glutinosa treated with various concentrations of EMS, R. glutinosa treated with 0. 03M EMS showed higher resistance against infection of F. oxysporum in pot tests, and Rehmannia glutinosa plants treated with 0.12M EMS showed higher resistance against infection of F. oxysporum in field tests.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.135-137
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• 2009

Mathematical models for describing the Human Immunodeficiency Virus(HIV) infection can be devised to better understand how the HIV causes Acquired Immune Deficiency Syndrome(AIDS). The HIV models can then be used to find clues to curing AIDS from a control theoretical point of view. Some models take Cytotoxic T Lymphocytes(CTL) response to HIV infection into account, and others consider mutants against the drugs. However, to the best of our knowledge, there has been no model developed, which describes CTL response and mutant HIV together. Hence we propose a unified model to consider both of these. On the basis of the resulting model, we also present a Model Predictive Control(MPC) scheme to find an optimal treatment strategy. The optimization is performed under the assumption that the Structured Treatment Interruption(STI) policy is employed.

• 한국식물학회:학술대회논문집
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• 한국식물학회 2001년도 춘계학술발표대회:발표눈문요지록
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• pp.15-15
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• 2001