• 한국미생물·생명공학회지
• /
• 제13권2호
• /
• pp.103-107
• /
• 1985

B. subtilis의 항생물질 내성균주에 대하여 여러 plasmid curing 시약인 sodium dodecyl sulfate, acriflavine, ethidium bromide, mitomycin-C등을 처리하여 streptomycin 감수성 변이주를 만들었다. Sodium dodecyl sulfate 처리의 경우 0.1% 농도에서 균체성장 극대기에 도달한 후부터 항생물질 감수성 비율이 증가되었으며, acriflavine 처리의 경우는 4$\mu\textrm{g}$/$m\ell$ 농도에서, ethidium bromide 처리의 경우에는 10$\mu\textrm{g}$/$m\ell$ 농도에서. 그리고 mitomycin-C 처리의 경우에는 200$\mu\textrm{g}$/$m\ell$ 농도에서 가장 curing빈도가 높았다. 또 이들 curing 작용은 B. subtilis의 streptomycin과 terramycin 내성균주에서 보는 바와 같이 경쟁적 작용으로 일어났다.

• Bulletin of the Korean Chemical Society
• /
• 제24권9호
• /
• pp.1324-1328
• /
• 2003

The simultaneous determination of anions ($SO_4 ^{2-},\;Cl^-,\;and\;NO_3^-$) and cations ($Na^+,\;NH^{4+},\;K^+,\;Mg^{2+},\;and\;Ca^{2+}$) in natural water obtained by Nakdong River waters system in Korea were performed by ion-exclusion/cationexchange chromatography with conductimetric detection. The stationary phase was a polymethacrylate-based weakly acidic cation-exchange resin column in the $H^+$-form and a weak-acid eluent. When using only a 1.4 mM sulfosalicylic acid/6 mM 18-crown-6 ether as an eluent, good resolution of both anions and cations, minimum time required for the separation, and satisfactory detection sensitivity were obtained in a reasonable time. The method was successfully applied to the simultaneous determination of anions and cations in natural waters.

• Bulletin of the Korean Chemical Society
• /
• 제27권4호
• /
• pp.524-528
• /
• 2006

Three different style capillary columns, a packed capillary with temporary quartz wool frit, a packed capillary with immobilized frit, and an immobilized packed-capillary, were easily prepared with a commercially available (S)-N-(3,5-dinitro-benzoyl)leucine-N-phenyl-N-alkylamide derived chiral stationary phase. Liquid chromatographic chiral separations of some racemic amino acid derivatives on these columns were performed and the results were compared to each other. The packed capillary with immobilized frit showed some merits in chiral chromatography.

• 대한치과기공학회지
• /
• 제21권1호
• /
• pp.139-144
• /
• 1999

토양시료로부터 치아우식원인균인 S. mutans에 대하여 항균력을 나타내는 방선균주를 순수분리하여 분리균주를 공시균주로 하여 항생물질 생성에 미치는 환경인자를 규명하였다. 본 공시균주의 항생물질 생성 최적배지조성은 Bacto-soytone 1%, glucose 1%, NaCl 0.5%, $CaCO_3$ 0.1% 였으며 배지의 초기 pH는 7.0이었다. 또한 항생물질은 $28^{\circ}C$에서 진탕배양시 생성의 최적조건이었으며 본 공시균주는 24시간 유도기를 거쳐 배양 72시간째 항생물질의 생성과 더불어 균의 최대증식도를 나타내었다.

• International Journal of Ocean System Engineering
• /
• 제1권3호
• /
• pp.136-143
• /
• 2011

In this paper, three-dimensional free-surface flows are simulated by using two different numerical methods, the constrained interpolation profile (CIP)-based and finite volume (FV)-based methods. In the CIP-based method, the governing equations are solved on stationary staggered Cartesian grids by a finite difference method, and an immersed boundary technique is applied to deal with wave-body interactions. In the FV-based method, the governing equations are solved by applying collocated finite volume discretization, and body-fitted meshes are used. A free-surface boundary is considered as the interface of the multi-phase flow with air and water, and a volumeof-fluid (VOF) approach is applied to trace the free surface. Among many variations of the VOF-type method, the tangent of hyperbola for interface capturing (THINC) and the compressive interface capturing scheme for arbitrary meshes (CICSAM) techniques are used in the CIP-based method and FV-based method, respectively. Numerical simulations have been carried out for dam-breaking and wave-body interaction problems. The computational results of the two methods are compared with experimental data and their differences are observed.

• Preventive Nutrition and Food Science
• /
• 제7권1호
• /
• pp.28-32
• /
• 2002

A Micrococcus sp. producing catalase was isolated from soil, and a commercial-scathe cultivation and purification of catalase were conducted. The maximum catalase activity was about 103 BU/mL obtained after 46 hr of cultivation in a 30 L fermenter containing 2% glucose, 2% peptone, 4% yeast extract, and 0.5% NaCl. Soybean sauce, CSL (corn steep liquor), and yeast extract were also studied as media substitutes in the media 30 L fermenter. The optimum medium components for the production catalase were found to be 2% glucose, 4% soybean sauce, and 16% CSL. In a 18 kL fermenter, the stationary phase in the cell growth and maximum catalase activity (112 BU/mL) were reached after 46 hr of cultivation, which was the same result as in the 30 L fermenter. The catalase activity was purified with over 17 folds in four steps with a 33.6% yield. From 104,250 mg of protein after cell lysis, 1,966 mg of the purified enzyme with a specific activity of 192.7 kBU/mg was obtained. The residual activity with the addition of 10% NaCl exhibited more than 100%. The use of just NaCl produced a higher residual activity than combination of bencol (benzyldimethyl ammoniumchloride) and PG (propyleneglycol).

• Bulletin of the Korean Chemical Society
• /
• 제25권6호
• /
• pp.900-906
• /
• 2004

An RPLC-postcolumn detection method has been developed for the fluorimetric determination of dichloroacetamide (DCAD) in water. After ammonia and DCAD were separated on a $C_{18}$ nonpolar stationary phase with 2.5% methanol-0.02 M phosphate buffer at pH 3, the column eluant was reacted with post column reagents, o-phthaldialdehyde (OPA) and sulfite ion at pH 11.5, to produce a highly fluorescent isoindole fluorophore, which was measured with a fluorescence detector ( ${\lambda}_{ex}$ = 363 nm, ${\lambda}_{em}$ = 425 nm). With the optimized conditions for RPLC and the postcolumn derivatization, the calibration curve was found to be linear in the concentration ranges of 0.5 and 20 ${\mu}$M for DCAD, and the detection limit for DCAD was 0.18 ${\mu}$M (23${\mu}$g/L). This corresponded to 18 pmol per 100 ${\mu}$L injection volume for a signal-to-noise ratio of 3, and the repeatability and reproducibility of this method were 1.0% and 2.5% for five replicate analyzes of 2 ${\mu}$M DCAD, respectively. The degradation yields DCAD to ammonia were 94 and 99%, and the percent recoveries of DCAD from 4 and 6 ${\mu}$M DCAD-spiked tap water were shown mean more than 97%.

• BMB Reports
• /
• 제40권1호
• /
• pp.113-118
• /
• 2007

Tolaasin, a pore-forming peptide toxin, is produced by Pseudomonas tolaasii and causes brown blotch disease of the cultivated mushrooms. P. tolaasii 6264 was isolated from the oyster mushroom damaged by the disease in Korean. In order to isolate tolaasin molecules, the supernatant of bacterial culture was harvested at the stationary phase of growth. Tolaasin was prepared by ammonium sulfate precipitation and three steps of chromatograpies, including a gel permeation and two ion exchange chromatographies. Specific hemolytic activity of tolaasin was increased from 1.7 to 162.0 HU $mg^{-1}$ protein, a 98-fold increase, and the purification yield was 16.3%. Tolaasin preparation obtained at each purification step was analyzed by HPLC and SDS-PAGE. Two major peptides were detected from all chromatographic preparations. Their molecular masses were analyzed by MALDI-TOF mass spectrometry and they were identified as tolaasin I and tolaasin II. These results demonstrate that the method used in this study is simple, time-saving, and successful for the preparation of tolaasin.

• Archives of Pharmacal Research
• /
• 제21권5호
• /
• pp.576-580
• /
• 1998

When glycosaminoglycan (GAG)-degrating enzymes were measured in normal human stool suspensions, all 5 tested different stools degraded titrable heparin and acharan sulfate. GAG-degrading bacteria were screened from the isolates of human stools. Among them, HJ-15 had the most potent activities of heparinases (GAGs-degrading enzymes). However, HJ-15 produced the enzyme even if in the media without heparin. Acharan sulfate lyase was induced by acharan sulfate and heparin. Heparinase production was also induced by these GAGs. These enzymes, acharan sulfate lyase and heparinase, were produced in exponential and stationary phase of HJ-15 growth, respectively. Optimal pHs of the acharan sulfate lyase and heparinase activities were 7.2 and 7.5 respectively. the biochemical properties of HJ-15 was similar to those of B. stercoris. However, difference from B. stercoris was utilization of raffinose. this HJ-15 also degraded chondroitin sulfates A and C.

• Bulletin of the Korean Chemical Society
• /
• 제26권10호
• /
• pp.1533-1538
• /
• 2005

We have determined the contents of monosaccharides in the hydrolysates of some yogurt and orange juice products by derivatizing monosaccharides with p-aminobenzoic acid ethyl ester (ABEE). The separation of the ABEE-derivatized monosaccharides was efficiently carried out by HPLC using a microcolumn packed with the Alltima $C_{18}$ stationary phase. The concentrations of monosaccharides were determined based on the measured peak area/height counts. ABEE derivatization of fructose and its detection have never been successfully carried out before this work. In this study, two peaks were observed in a fixed ratio for ABEE-fructose, and the ratio was maintained over a wide range of fructose concentration. In order to prove the validity of the above method, we compared the concentrations of glucose, galactose and fructose determined by ABEE derivatization and UVD (ultraviolet detector) chromatography with those determined by RID (refractive index detector) chromatography without derivatization. The determined concentrations of monosaccharides obtained from the two chromatographic methods were found close to each other within acceptable error ranges.