• Journal of Applied Biological Chemistry
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• 제51권3호
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• pp.128-135
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• 2008

A total of 142 samples comprising vegetables, soil, and water collected from different agricultural farms (five provinces) were analyzed for total aerobic bacteria (aerobic plate count [APC]), Bacillus cereus, Escherichia coli, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus. The average of total APC in all the samples ranged from $4.72{\times}10^5$ to $8.62{\times}10^8\;CFU/g$ (mL). The prevalence of B. cereus, E. coli, L. monocytogenes, S. spp., and S. aureus for all samples was 17.60%, 2.11 %, 1.4%, 0%, and 2.11 % respectively, and their counts averaged to $4.87{\times}10^4\;CFU/g$ (mL), $4.34{\times}10^3\;CFU/g$ (mL), $2.15{\times}10^2\;CFU/g$, 0 CFU/g, and $3.12{\times}10^3\;CFU/g$ respectively. Among the 3 different types of samples, 6 vegetables (10.34%), 24 soil (38.70%), and 3 water (13.64%) samples were found to be positive for bacterial pathogens. The result showed that the occurrence of bacterial pathogen in the samples analyzed was low. Further time to time monitoring and need to wash of raw agricultural products is recommended.

• Journal of Microbiology and Biotechnology
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• 제18권6호
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• pp.1064-1069
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• 2008

Levan fructotransferase (LFTase) preferentially catalyzes the transfructosylation reaction in addition to levan hydrolysis, whereas other levan-degrading enzymes hydrolyze levan into a levan-oligosaccharide and fructose. Based on sequence comparisons and enzymatic properties, the fructosyl transfer activity of LFTase is proposed to have evolved from levanase. In order to probe the residues that are critical to the intramolecular fructosyl transfer reaction of the Microbacterium sp. AL-210 LFTase, an error-prone PCR mutagenesis process was carried out, and the mutants that led to a shift in activity from transfructosylation towards hydrolysis of levan were screened by the DNS method. After two rounds of mutagenesis, TLC and HPLC analyses of the reaction products by the selected mutants revealed two major products; one is a di-D-fructose-2,6':6,2'-dianhydride (DFAIV) and the other is a levanbiose. The newly detected levanbiose corresponds to the reaction product from LFTase lacking transferring activity. Two mutants (2-F8 and 2-G9) showed a high yield of levanbiose (38-40%) compared with the wild-type enzyme, and thus behaved as levanases. Sequence analysis of the individual mutants responsible for the enhanced hydrolytic activity indicated that Asn-85 was highly involved in the transfructosylation activity of LFTase.

• Korean Chemical Engineering Research
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• 제55권1호
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• pp.80-85
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• 2017

최근 고부가가치 산물의 생산이 가능한 미세조류는 이산화탄소의 생물학적 전환 측면에서 많은 주목을 받고 있다. 그렇지만 미세조류 종 자체가 지닌 낮은 광합성 효율 및 생산성의 한계는 미세조류를 활용한 공정의 상업화를 막는 장애요인이다. 따라서 본 연구에서는 대표 미세조류 Chlamydomonas reinhardtii의 광독립영양 성장성 분석을 위한 미세액적 광생물반응기를 개발하였다. PDMS 기반의 미세유체 칩 내에 미세기둥을 배열하고 미세챔버의 높이를 조절하여 미세액적 내 이산화탄소의 전달속도를 증가시켰으며, 이는 세포 성장성과 형광 세기 변화를 통해 확인하였다. 마지막으로 미세액적 광생물반응기를 활용하여 다양한 이산화탄소 농도 및 광량 조건에서 C. reinhardtii의 광독립영양배양에서 성장성을 96 시간동안 관찰하고 분석하였다. 본 연구 결과를 통해 미세액적 광생물반응기는 성장성 및 유용물질 생산성이 우수한 미세조류 종을 빠르게 분석하고 쉽게 분리할 수 있는 효율적인 플랫폼임을 입증하였다.

• Molecules and Cells
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• 제46권8호
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• pp.513-525
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• 2023

Orange carotenoid protein (OCP) of photosynthetic cyanobacteria binds to ketocarotenoids noncovalently and absorbs excess light to protect the host organism from light-induced oxidative damage. Herein, we found that mutating valine 40 in the α3 helix of Gloeocapsa sp. PCC 7513 (GlOCP1) resulted in blue- or red-shifts of 6-20 nm in the absorption maxima of the lit forms. We analyzed the origins of absorption maxima shifts by integrating X-ray crystallography, homology modeling, molecular dynamics simulations, and hybrid quantum mechanics/molecular mechanics calculations. Our analysis suggested that the single residue mutations alter the polar environment surrounding the bound canthaxanthin, thereby modulating the degree of charge transfer in the photoexcited state of the chromophore. Our integrated investigations reveal the mechanism of color adaptation specific to OCPs and suggest a design principle for color-specific photoswitches.

• 한국약용작물학회지
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• 제24권2호
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• pp.143-151
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• 2016

Background: The public has increasing concerns about herbal crops owing to insufficient information on biological hazards such as foodborne pathogens. Therefore, the objective of this study is the development of a herbal crop quality control system through monitoring with biological hazard analysis. Today, it is estimated that millions of people become ill every year from food contamination. The public demands agricultural products of stable and consistent quality. Governments have the responsibility of establishing the standards, legislation and enforcement programs necessary to control food quality and safety. However, research on the biosafety of herbal crop products is still insufficient. Therefore, the implementation of monitoring systems with high standards is critical for public safety. Methods and Results: In this study, we collected 52 samples of herbal crop products, and conducted both quantitative and qualitative biological hazard analysis. With biological hazard analysis, aerobic bacteria, Staphylococcus aureus, Salmonella spp., Escherichia coli, Coliforms, and Listeria spp. could be detected. Conclusions: Herbal crops were found to be contaminated with aerobic bacteria at $3.69{\pm}0.32log\;CFU/g$. Staphylococcus aureus, Salmonella spp., Escherichia coli, Coliforms, and Listeria spp. were not detected in any of the samples. This research suggests that continuous monitoring of biological hazards is required to improve the quality of herbal crops.

• 한국식품위생안전성학회지
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• 제34권2호
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• pp.191-198
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• 2019

쑥갓의 안전성 확보를 위하여 쑥갓 재배기간 중 bifenthrin 및 chlorothalonil의 잔류양상을 연구하였다. 쑥갓에 유효성분 bifenthrin을 살포 후 0일(3시간)은 $0.90{\pm}0.07mg/kg$을 보였고, 26일후에는 $0.14{\pm}0.01mg/kg$이었으며, chlorothalonil은 0일(3시간)에 $79.12{\pm}6.02mg/kg$, 26일후에는 $4.60{\pm}1.33mg/kg$으로 나타났다. 쑥갓 중 bifenthrin과 chlorothalonil의 회수율은 각각 $88.67{\pm}7.97%$와 $99.90{\pm}16.03%$로 유효한 회수율 범위를 보였다. 쑥갓의 생육 기간 중 농약의 잔류량 변화는 first order kinetics model을 적용하여 해석한 결과 bifenthrin의 반감기는 9.63일이었으며, chlorothalonil은 6.54일이었다. 산출된 두 농약의 감소상수를 이용하여 생산단계 잔류 허용기준을 산출한 결과 bifenthrin의 수확 26일 전 잔류량은 11.7 mg/kg이었으며, chlorothalonil은 24.1 mg/kg이었는데 수확 예정일에는 두 농약의 잔류허용기준이 모두 5.0 mg/kg 이하로 잔류하여 안전할 것으로 판단되었다. 쑥갓 생산단계 농산물의 농약 잔류허용기준을 설정하는데 기초자료로 활용하여 농산물 유통단계의 부적합에 따른 생산자의 경제적 손실을 최소화하고 소비자에 대한 안전성을 강화할 수 있다고 사료된다.

• 한국유변학회:학술대회논문집
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• 한국유변학회 2006년도 춘계 학술발표회 논문집
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• pp.81-84
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• 2006

Slot coating process, in continuous and patch modes, has been applied for the many precise coating products, e.g., flat panel displays and second batteries. However, manufacturing uniform coating products is not a trivial task at high-speed operations because various flow instabilities or defects such as leaking, bubbles, ribbing, and rivulets are frequently observed in this process. It is no wonder, therefore, that many efforts to understand the various aspects of dynamics and coating windows of this process have been made both in academia and industry. In this study, as the first topic, flow dynamics within the coating bead in slot coating process has been investigated using the one-dimensional viscocapillary model by lubrication approximation and two-dimensional model by Flow-3D software. Especially, operability windows in both 1D and 2D cases with various slot die lip designs have been successfully portrayed. Also, effects of process conditions like viscosity and coating gap size on slot coating window have been analyzed. Also, some experiments to find minimum coating thickness and coating windows have been conducted using slot die coater implemented with flow visualization device, corroborating the numerical results. As the second topic, flow dynamics of both Newtonian and Non-Newtonian fluids in patch or pattern slot coating process, which is employed in manufacturing IT products such as secondary batteries, has been investigated for the purpose of optimal process designs. As a matter of fact, the flow control in this system is more difficult than in continuous case because od its transient or time-dependent nature. The internal die and die lip designs for patterned uniform coating products have been obtained by controlling flow behaviors of coating liquids issuing from slot. Numerical simulations have been performed using Fluent and Flow-3D packages. Flow behavior and pressure distribution inside the slot die has been compared with various die internal shapes and geometries. In the coating bead region, efforts to reduce irregular coating defects in head and tail parts of one patterned coating unit have been tried by changing die lip shapes. It has been concluded that optimal die internal design gas been developed, guaranteeing uniform velocity distribution of both Newtonian and shear thinning fluids at the die exit. And also optimal die lip design has been established, providing the longer uniform coating layer thickness within one coating unit.

• 한국해양바이오학회지
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• 제2권1호
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• pp.11-22
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• 2007

This aims to review natural products transformed by mimic intestinal metabolisms with microorganisms and hydrolytic enzymes, which exhibit enforced biological activity, higher extraction yield and identification of active components. In the process, transformation to the smaller active compounds with enzymes and microbes mimics the pharmacological action of natural products by intestinal bacteria. In order to establish conditions for the fermentation and enzyme reaction, it is required to choose several natural products for biotransformation and investigate the optimal conditions for the fermentation or the enzyme reaction such as composition, temperature, pH, inoculum, and cultivation time. It is expected an increase of the internal absorption of the active materials without regard to the intestinal microbes or its ability through biosynthesis of the active materials by the microbes and enzymes. And this techniques can be applied to biotransformation of natural products such as sesaminol, resveratrol, 1-deoxy nojirimycin, naringenin, quercetin, and baicalin and to the metabolism study using the animal model.

• 한국작물학회지
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• 제51권spc1호
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• pp.1-6
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• 2006

Tocotrienol의 건강식품 및 의료용 가공품으로의 고부가가치화 가능성을 평가하기 위하여 미강에서 추출한 tocotrienol의 항암 효과 및 독성평가를 실시하였다. HepG2 간암 세포를 대상으로 한 항암효과 분석 결과 tocotrienol이 간암세포의 증식을 억제함을 입증할 수 있었다. 또한 랫드를 이용한 경구독성 검사를 수행한 결과 tocotrienol 최종 생산물은 경구투여 한계량인 $2,000mg\;kg^{-1}$ 수준에서도 사망률, 일반 증상, 체중 변화 등에 이상을 보이지 않았으며, 부검 후 흉강 및 복강의 모든 장기에 대한 육안적 부검 소견 등에서도 아무런 독성학적 변화가 유발되지 않음을 알 수 있었다.

• 한국응용과학기술학회지
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• 제28권4호
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• pp.438-448
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• 2011

Chitosan is widely used in cosmetics and medical fields. Special emphasis has been put on the chemical modification of chitosan to explore its full potential. We have described the synthesis and biological activity of novel peptide amino acid derivatives. The polyamino acid derivatives were synthesized by introducing alkylamine functional group on chitosan at C-6. The poor aqueous solubility of chitosan derivatives hinder both pharmacological studies and pharmaceutical development. To make amino acid coupled chitosan derivatives with improved biological effect and solubility, some attempts have been taken to consist of amino peptide group like aspartic acid and phenylalanine-aspartic acid derivatives onto chitosan C-6. The resultingly substituted chitosan was characterized by solubility in various solvents. We measured chitosan derivatives with $^1H$-NMR and $^{13}C$-NMR. Also, We were investigated on the physical properties and biological activities of these products.