Dahyeok Kweon

We examined butanol fermentation by Clostridium beijerinckii NCIMB 8052 using various hydrolyzates obtained from rice bran, which is one of the most abundant agricultural by-products in Korea and Japan. In order to increase the amount of fermentable sugars in the hydrolyzates of rice bran, various hydrolysis procedures were applied. Eight different hydrolyzates were prepared using rice bran (RB) and defatted rice bran (DRB) with enzyme or acid treatment or both. Each hydrolyzate was evaluated in

This study was carried out to optimize the conditions for the extraction of antioxidative materials from licorice root, Glycyrrhiza glabra. Chipped licorice roots were extracted with several solvents and their antioxidative activities were tested to determine the optimal extraction solvent. Among the solvents tested, 95% ethanol gave the highest free radical scavenging activity, and was therefore chosen as the optimal extracting solvent. The optimum extraction temperature and time were 20oC and

Conditions for extraction of antimicrobial materials from licorice root, Glycyrrhiza glabra, were optimized. Among solvents tested, 95% ethanol gave highest antimicrobial activity, and was chosen as optimal extracting solvent. Extraction temperature and time were optimal at room temperature and for 12 hr, respectively. Minimal inhibitory concentration (MIC) of 95% ethanol extracts was determined against 14 microorganisms. Reference microorganisms included 6 Gram(-) bacteria, 4 Gram(+) bacteria,

Conversion of the normal soluble form of prion protein, PrP (PrPC), to proteinase K-resistant form (PrPSc) is a common molecular etiology of prion diseases. Proteinase K-resistance is attributed to a drastic conformational change from α-helix to β-sheet and subsequent fibril formation. Compelling evidence suggests that membranes play a role in the conformational conversion of PrP. However, biophysical mechanisms underlying the conformational changes of PrP and membrane binding are still elusive.

The PhoP response regulator and PhoQ sensor, which are encoded by the phoPQ operon, constitute the PhoP/PhoQ two-component system. Genome-wide transcription ana-lysis revealed that heterologous expression of the RstB protein, a sensor of the RstA/RstB two-component system, leads to enhanced transcription of PhoP-activated genes in wild-type Salmonella. We determined that RstB-induc-tion increases the levels of phoP mRNA as well as PhoP protein, while lack of the phoPQ genes abolishes RstB-promot

2'-Fucosyllactose (2'-FL), the most abundant fucosylated oligosaccharide in human milk, has multiple beneficial effects on human health. However, its biosynthesis by metabolically engineered Escherichia coli is often hampered owing to the insolubility and instability of α-1,2-fucosyltransferase (the rate-limiting enzyme). In this study, we aimed to enhance 2'-FL production by increasing the expression of soluble α-1,2-fucosyltransferase from Helicobacter pylori (FucT2). Because structural inform

본 연구는 어류 병원균의 비 유전성을 가지는 항생제 내성균인 persister cell에 관한 연구이다. Persister cell은 기존의 항생제를 분해하는 저항균체(resistant cell)와는 다른 특성으로 항생제에 대한 저항성을 가지는데, 항생제가 존재하는 환경에서 새로운 기작으로 항생제에 대한 내성을 형성한다. 그래서 기존의 양식장에서 어류를 키울 때 어류에 투여하는 항생제는 일반적인 균주의 사멸 항생제 농도보다 더 높은 농도의 항생제를 투여하게 된다. 특히, E. tarda에 대한 다양한 항생제가 개발되어 있지만 내성균의 출현으로 그 효과가 좋지 않으며, 또한 persister cell에 의한 질병 재발을 방지하기 위해 균사멸 농도보다 훨씬 높은 농도의 항생제를 처리하고 있다. Persiser cell의 특이적인 저감 효과를 확인 하기 위하여 선별된 3종의 식물 추출물(돌외, 예덕나무, 상산)을 항생제와 함께 사용하였으며, 돌외와 예덕나무가 100 μg/ml, 상산은 2

2’-Fucosyllactose (2’-FL) is one of the most important human milk oligosaccharides and has several health benefits for infants. The levels of 2’-FL in breast milk or samples from other sources can be quantified by high-performance liquid chromatography. However, this method cannot be used for simultaneous detection of the target compound in numerous samples. Here, we developed a simple method for quantifying 2’-FL in a microplate format. The method involves two steps: (i) release of L-fucose fro

Optimum conditions for production of casein phosphopeptides (CPP) from sodium casenate by immobilized cell culture of Streptococcus faecalis var. liquefaciens were investigated. Immobilized cells were made by mixing 60% sodium alginate solution with an equal volume of culture broth at the end of exponential phase and subsequently dropping the mixture into CaCl2 solution. Optimum conditions for CPP production by the immobilized cells were the same as those (50℃, pH 7.0, and 10% substrate concentr

Foot-and-mouth disease virus (FMDV) is a small single- stranded RNA virus which belongs to the family Picornaviridae, genus Apthovirus. It is a principal cause of FMD which is highly contagious in livestock. In a wild type virus infection, infected animals usually elicit antibodies against structural and non-structural protein of FMDV. A structural protein, VP1, is involved in neutralization of virus particle, and has both B and T cell epitopes. A RNA-dependent RNA polymerase, 3D, is highly cons

Epothilone B (EpoB) is a paclitaxel (PTX)-like microtubule-stabilizing agent that induces mitotic arrest and apoptosis in cells. EpoB is a promising anti-tumor agent, and is thought to have the potential to overcome well-known PTX resistance. However, EpoB is barely soluble in water, and is fatal to normal cells due to extremely potent cytotoxicity. To reduce the unwanted cytotoxicity of EpoB to normal cells, a reconstituted highdensity lipoprotein (rHDL)-like nanoparticle of EpoB (EpoB-rHDL) wa

Recently, the clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (CRISPR/Cas9) system, a genome editing technology, was shown to be versatile in treating several antibiotic-resistant bacteria. In the present study, we applied the CRISPR/ Cas9 technology to kill extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli. ESBL bacteria are mostly multidrug resistant (MDR), and have plasmid-mediated antibiotic resistance genes that can be easily transfer

Gel resins modified with different phenylboronic acid derivatives were prepared for selective separationof catechol-containingflavonoids. The phenylboronic acid gel (PBA-gel) resins showed pH-dependentadsorption and release of catechol-containingflavonoid quercetin. Under optimal pH control, the PBA-gelresins exhibited high quercetin binding capacity of up to 120 mg/g of resin and demonstrate quantitativerelease of the specifically bound quercetin. In addition, the recyclability of PBA-gel resin

Policosanol production process from crude waxes obtained after rice bran oil was studied. First, the amount of NaOH which is added for the hydrolysis of crude waxes into fatty alcohols and fatty acids was optimized. By adding NaOH into crude waxes with 8:1 molar ratio, fatty alcohols were released. Subsequently 30% CaCl2 solution was added into the mixture of fatty alcohols and fatty acids for double decomposition, which resulted in the precipitation of fatty acids. After crystallization and was