• 한국조리학회지
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• 제9권3호
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• pp.114-129
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• 2003

This study aimed at drawing a scheme for more developmental and rational improvement of the screening examination system to cope with the rapidly changing industrial environment positively, enhance the food service industry qualitatively, and reinforce engaged specialty of those engaged in the industry. To set a rational improvement scheme for a cook screening system, the study conducted a prior study on job analysis of those engaged in cooking, a review on relevant laws, and a theoretical research on those problems in the current cook screening examination system. On this basis, it understood the actual condition of the current cook screening system and implemented a demonstrative analysis through a survey to draw a section on a future improvement scheme. The results were analyzed largely from two viewpoints: the general condition of the cook screening system and the future improvement scheme for the system.

• 한국잡초학회지
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• 제13권2호
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• pp.81-88
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• 1993

광합성 전자전달저해제의 탐색을 위한 biorational biorational screening 방법으로 광합성 박테리아의 일종인 cyanobacteria의 표준형과 $D_1$단백질의 구성 아미노산이 변환된 변이주 Di-1, G-264, Di-22, TRY-5를 사용하여 기존 약제의 혼합효과와 몇가지 합성화합물의 Hill반응 저해활성을 측정 조사하였고, 또한 시금치로 부터 분리한 chloroplast와 cyanobacteria로 부터 분리한 thylakoid membrane에 대한 기존 제초제의 반응성을 조사하였다. 1. 광합성억제형 제초제에 대한 반응성 비교에서 cyanobacteria로 부터 분리한 thylakoid membrane이 시금치로 부터 분리한 chloroplast보다 약제에 대하여 민감한 반응을 나타내어 광합성 전자전달저해제의 탐색을 위한 재료로 보다 적합하였다. 2. Diuron에 대하여 wild type보다 Di-22와 D-5 변이주는 각각 약 2,000배와 800배의 저항성을 나타내었고 atrazine에 대하여는 G-264 변이주만이 약 1,000배의 저항성을 나타내었으며, 기타 네 약제에 대하여는 뚜렷한 저항성을 나타내는 변이주가 없었다. 3. D1 단백절의 264번 위치의 serine이 다른 아미노산으로 치환된 Di-1과 D-22 및 G-264 변이주에 대한 diuron과 atrazine의 혼합처리 효과를 검토한 결과 상호 경합적으로 작용하였으며 그 정도는 G-264 변이주에 대해서 가장 뚜렷하게 나타났다. 그러나 diurone과 atrazine의 혼합처리에 의한 thermoluminescence band의 변화는 인정할 수 없었다. 4. 변이주 Di-1과 D-22는 dinoseb에 대해서 저항성을 나타내지 않았으나. dinoseb과 diuron의 혼합처리시 diuron에 대한 저항성이 크게 약화되었다.

• KSBB Journal
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• 제20권5호
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• pp.376-382
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• 2005

AVM $B_{1a}$는 Streptomyces avermitilis가 생합성하는 이차대사산물로, 강력한 구충효과를 갖는 polyketide 계열의 물질이다. AVM $B_{1a}$ 생합성의 전구체로 isoleucine이 사용되고 AVM의 생합성 경로가 지방산 합성과 유사하므로, 전구체를 과량생합성하고 polyketide 생합성 경로로 진행되는 탄소원의 흐름이 증가된 변이주를 선별하기 위하여 isoleucine의 아미노산 유사체 (O-methyl threonine)와 지방산 합성 저해물질 (p-fluoro phenoxy acetic acid)에 대한 저항성 변이주를 선별하고자 하였다. 모균주의 AVM $B_{1a}$ 생산성은 약 100 units/L로 매우 낮은 반면, 100 ppm의 pFAC에 대한 저항성 변이주인 PFA-1는 약 4,200 units/1의 AVM $B_{1a}$를 생산하는 것으로 관찰되었다. 이 균주를 모균주로 하여 OMT에 대한 저항성을 지속적으로 증가시킬 경우 AVM $B_{1a}$ 생산성이 2배 더 증가한 약 9,000 units/1의 생합성 능력을 보이는 고생산성 변이주를 개발할 수 있었다. 또한 주목할 만하게도 지방산 저해물질인 PFAC에 대한 변이주의 저항성을 지속적으로 증가시킴으로써 AVM $B_{1a}$ 생산성이 11,000 units/L에 이르는 고역가 변이주를 선별할 수 있었다. 한편 상기의 OMT와 pFAC를 이용한 rational screening 전략을 통해 지속적으로 선별한 변이주들에 대한 AVM $B_{1a}$의 생산성 분포를 histogram을 통해 분석해 본 결과, 초반부에 선별된 돌연변이주들은 AVM $B_{1a}$의 생합성 능력에 있어서 거의 모두가 ($95\%$ 이상) 4,000 units/1 이하의 비교적 낮은 범위에 분포하는 반면, OMT와 pFAC의 농도를 높여가며 유도된 저항성 돌연변이주들의 경우에는 이들 중에 고생산성 균주의 비율이 뚜렷하게 증가 (OMT 에서 $5,000\~7,000$ unit/l 범위에 $71\%$; pFAC에서 $6,000\~7,000$ unit/L 범위에 $47\%$) 하는 것으로 확인되었다. 이로부터 polyketide 생합성 경로와 AVM $B_{1a}$의 생합성 경로의 이해를 통해 수행된 rational screening 전략이 AVM $B_{1a}$ 고생산성 뿐만 아니라 고 안정성의 특성을 갖는 균주를 선별하는데 매우 효율적임을 알 수 있었다.

• 대한약학회:학술대회논문집
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• 대한약학회 2001년도 Proceedings of International Convention of the Pharmaceutical Society of Korea
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• pp.244.3-245
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• 2001

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.228-232
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• 2003

Lovastatin produced by Aspergillus terreus via polyketide pathway is a secondary metabolite with high anti-hypercholesterolemic activity. In this paper we are going to present effective strain development strategies for lovastatin production by comparing the productivity of the mutants obtained through traditional rational screening process and protoplast fusion method. Mutants resistant against various antibiotics and/or antimetabolites showed significantly higher lovastatin productivity than the corresponding mother strains, demonstrating that rational screening method was very efficient in selecting high yielding producers. Recombinant fusants obtained using protoplast fusion between high producers were observed to have very different morphology and physiology as represented by the production and secretion of lovastatin, as well as cell growth pattern. In parallel with the strain development, optimization process for the production medium was carried out in order to find optimal concentrations of the medium components using such a powerful statistical method as response surface method (RSM). It was concluded that not only the optimum production medium but also good morphological characteristics of the high-yielding producers led to higher lovastatin production.

• Journal of Microbiology and Biotechnology
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• 제29권3호
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• pp.419-428
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• 2019

Phytases are enzymes that can hydrolyze phytate and its salts into inositol and phosphoric acid, and have been utilized to increase the availability of nutrients in animal feed and mitigate environmental pollution. However, the enzymes' low thermostability has limited their application during the feed palletization process. In this study, a combination of B-value calculation and protein surface engineering was applied to rationally evolve the heat stability of Escherichia coli phytase. After systematic alignment and mining for homologs of the original phytase from the histidine acid phosphatase family, the two models 1DKL and 1DKQ were chosen and used to identify the B-values and spatial distribution of key amino acid residues. Consequently, thirteen potential amino acid mutation sites were obtained and categorized into six domains to construct mutant libraries. After five rounds of iterative mutation screening, the thermophilic phytase mutant P56214 was finally yielded. Compared with the wild-type, the residual enzyme activity of the mutant increased from 20% to 75% after incubation at $90^{\circ}C$ for 5 min. Compared with traditional methods, the rational engineering approach used in this study reduces the screening workload and provides a reference for future applications of phytases as green catalysts.

• Journal of Microbiology and Biotechnology
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• 제33권10호
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• pp.1257-1267
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• 2023

Although rational genetic engineering is nowadays the favored method for microbial strain improvement, building up mutant libraries based on directed evolution for improvement is still in many cases the better option. In this regard, the demand for precise and efficient screening methods for mutants with high performance has stimulated the development of biosensor-based high-throughput screening strategies. Genetically encoded biosensors provide powerful tools to couple the desired phenotype to a detectable signal, such as fluorescence and growth rate. Herein, we review recent advances in engineering several classes of biosensors and their applications in directed evolution. Furthermore, we compare and discuss the screening advantages and limitations of two-component biosensors, transcription-factor-based biosensors, and RNA-based biosensors. Engineering these biosensors has focused mainly on modifying the expression level or structure of the biosensor components to optimize the dynamic range, specificity, and detection range. Finally, the applications of biosensors in the evolution of proteins, metabolic pathways, and genome-scale metabolic networks are described. This review provides potential guidance in the design of biosensors and their applications in improving the bioproduction of microbial cell factories through directed evolution.

• Journal of Preventive Medicine and Public Health
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• 제24권1호
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• pp.16-28
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• 1991

Service diversification is recognized as an important strategy against turbulent environmental change. This study is designed to find out the trend of service diversification in Korean health care organizations and also to identify factors associated with the degree of service diversification. Data were collected from 69 hospitals out of 71 hospitals with over 300 beds. Important findings are summarized below. 1. Types of diversification are closely related to hospital size. Large hospitals have a tendency to provide sophisticated services requiring specialized skills and equipment, while small hospital have concentrated their efforts on health screening programs. 2. The more competitive and bigger hospitals are, the greater number of services that provide. Also, hospitals operating rational management information systems provide more services. Contrary to the expectation hospitals with a low performance during last 3 years showed more service diversification. 3. A trend of more diversification was observed in hospitals whose chief executive officer used a prospector strategy. 4. A multiple regression analysis revealed that bed size, competitive environment, degree of rational management, and the growth pattern were significantly associated with the service diversification.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.92-93
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• 2002

With the recent development of combinatorial chemistry, recombinant biotechnology and rational drug design, millions of compounds are being produced in the laboratories of pharmaceutical companies. These new drug candidates are evaluated their efficacy and toxicity through in vivo animal model studies which is very important in drug development. From these studies, very successful drug candidates are selected. (omitted)

• Journal of Pharmaceutical Investigation
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• 제33권3호
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• pp.157-162
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• 2003

The feasibility of [P(AA-co-PEGMM)] film as a buccal mucoadhesive patch was previously reported by estimating mucoadhesiveness and release characteristics. To find a rational penetration enhancer of [P(AA-co-PEGMM)] film containing butorphanol tartrate (Bt), penetration of Bt from [P(AA-co-PEGMM)] film which contained various additives was estimated by measuring its flux, Papp and lag tme in in vitro buccal membrane of porcine. EDTA showed almost no increase of Bt permeability, wherease SGC, STDHF and SLS increased the permeability of Bt with the order of SGC > STDHF > SLS. The rational additive concentration of SGC was 4% and its Papp and lag time were $1.93{\times}10^{-4}{\pm}4.21{\times}10^{-6},\;126.60{\pm}21.88min\;(control\;:\;Papp\;0.45{\times}10^{-4};\;lag\;time\;211.01{\pm}16.77\;min)$, respectively.