• Journal of Microbiology and Biotechnology
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• v.7 no.1
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• pp.8-12
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• 1997

In order to overproduce D-xylose isomerase, the Escherichia coli D-xylose isomerase (D-xylose ketol-isomerase, EC 5.3.1.5) gene (xylA) was fused to ${\lambda}P_{L}$ promoter. The promoterless xylA gene containing the ribosome binding site and coding region for D-xylose isomerase was cloned into a site 0.3 kb downstream from the ${\lambda}P_{L}$ promoter on a high copy number plasmid. An octameric XbaI linker containing TAG amber codon was inserted between 33rd codon of ${\lambda}N$ and the promoterless xylA gene. The resulting recombinant plasmid (designated as pPX152) was transformed into E. coli M5248 carrying a single copy of the temperature sensitive ${\lambda}cI857$ gene on its chromosomal DNA. When temperature-induced, the transformants produced 15 times as much D-xylose isomerase as that of D-xylose-induced parent strain. The amount of overproduced D-xylose isomerase was found to be about 60% of total protein in cell-free extracts.

• Journal of Microbiology and Biotechnology
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• v.18 no.4
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• pp.639-647
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• 2008

The heat-inducible expression vectors for Corynebacterium glutamicum and C. ammoniagenes were constructed by using the ${\lambda}O_L1$ and the cryptic promoters, CJ1 and CJ4 that express genes constitutively in C. ammoniagenes. Although the promoters were isolated from C. ammoniagenes, CJ1 and CJ4 were also active in C. glutamicum. To construct vectors, the $O_L1$ from the ${\lambda}P_L$ promoter was isolated and fused to the CJ1 and CJ4 promoters by recombinant PCR. The resulting artificial promoters, CJ1O and CJ4O, which have one ${\lambda}O_L1$, and CJ1OX2, which has two successive ${\lambda}O_L1$, were fused to the green fluorescent protein (GFP) gene followed by subcloning into pCES208. The expression of GFP in the corynebacteria harboring the vectors was regulated successfully by the temperature-sensitive cI857 repressor. Among them, C. ammoniagenes harboring plasmid pCJ1OX2G containing GFP fused to CJ1OX2 showed more GFP than the other ones and the expression was tightly regulated by the repressor. To construct the generally applicable expression vector using the plasmid pCJ1OX2G, the His-tag, enterokinase (EK) moiety, and the MCS were inserted in front of the GFP gene. Using the vector, the expression of pyrR from C. glutamicum was tried by temperature shift-up. The results indicated that the constructed vectors (pCeHEMG) can be successfully used in the expression and regulation of foreign genes in corynebacteria.

• Korean Journal of Materials Research
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• v.6 no.8
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• pp.852-857
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• 1996

Crystallization characteristics of titanium oxide thin film during post-annealing of reactive sputter deposition were studied. Amorphous phases of as-deposited films were crystallized into rutile after annealing at $900^{\circ}C$ and anatase at $500^{\circ}C$, respectively when $O_2$ concentration during sputtering was more than 15%. However, rutile was the only phase obtainable after annealing if %$O_2$ was less than 10%. For these films, Magneli phase($Ti_nO_{2n-1}$) were crystallized below $500^{\circ}C$ at first place due to slow oxidation of nonstoichiometric films but $500^{\circ}{\sim}600^{\circ}C$ anatase with nonstoichiometry was crystallized for a short period. It was, therefore, concluded that crystal growth can proceed without phase transition if stoichiometric phase is formed at the first stage of crystallization, and that rutile, the most stable phase, was resulted from any oxygen deficient nonstoichiometric films.

• Korean Journal of Microbiology
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• v.48 no.4
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• pp.293-297
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• 2012

Of the 169 strains of microorganisms stored in Polar and Alpine Microbial Collection of Korea Polar Research Institute, 27 strains were selected for their chitinase activity on ZoBell plates supplemented with 0.4% colloidal chitin. Among them, PAMC 21693 strain have shown the highest chitinolytic enzyme activity toward pNP-$(GlcNAc)_1$ at low temperature and the highest growth rate at $4^{\circ}C$. We cloned a full-length chitinase gene of 2,857 bp which contains an open reading frame of 2,169 bp encoding 872-amino acid polypeptide. Recombinant chitinase protein was expressed in E. coli and its molecular weight was confirmed 96 kDa. In this paper, we suggest the potential use of cold-active chitinase from polar microorganisms in the field of biotechnology.

• Journal of Microbiology and Biotechnology
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• v.2 no.1
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• pp.26-34
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• 1992

The effect of induction temperature on fermentation parameters has been investigated extensively using Escherichia coli M5248[pNKM21], a producer of recombinant human interleukin-2 (rhIL-2). In this recombinant microorganism, the gene expression of rhIL-2 is regulated by the cI857 repressor and $P_L$ promoter system. The recombinant fermentation parameters studied in this work include the cell growth, protein synthesis, cell viability, plasmid stability, $\beta$-lactamase activity, and rhIL-2 productivity. Interrelationships of such fermentation parameters have been analyzed through a quantitative assessment of the experimental data set obtained at eight different culture conditions. While the expression of rhIL-2 gene was repressed at culture temperatures below $34^\circ{C}$ with little effect on other fermentation parameters, under the conditions of rhIL-2 production $>(36~44^\circ{C})$ the cell growth, plasmid stability, and $\beta$-lactamase activity were, as induction temperature was increased, more profoundly reduced. Although the rhIL-2 content in the insoluble protein fraction was maximum at $40^\circ{C}$, total rhIL-2 production in the culture volume was found to be highest at the induction temperature of $36^\circ{C}$. This was in contrast to the previously known optimum induction temperature of the P$_{L}$ promoter system $>(40~42^\circ{C})$.Explanations for such a discrepancy have been proposed based on a product formation kinetics, and their implications have been discussed in detail.l.

• Journal of the Korean Ceramic Society
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• v.35 no.8
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• pp.857-863
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• 1998

The BaTiO3 powders extensively used as MLCC (Multilayer ceramic capacitor) in electronic ceramic in-dustry were synthesized by GNP (Glycine-Nitrate process) The powders were prepared using carbonate and alkoxide as starting materials and nitric acid was used as a solvent for starting materials as well as an oxidant for combustion. The BaTiO3 powders were synthesized using different amounts of glycine as a fuel for combustion. The characteristics of synthesized powders were examined with helium pycnometer X-ray diffraction(XRD) Brunauer-Emmett-Teller with N2 adsorption and scanning electron microscopy(SEM). It was found that single phase BaTiO3 could be formed when the as-synthesized powders were heat-treated at 100$0^{\circ}C$ When the glycine/cation molar ratio was 1,2 specific surface area was 24m2/g

• Journal of Animal Science and Technology
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• v.47 no.5
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• pp.857-866
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• 2005

This study was carried out to evaluate changes in taste compounds of seasoned pork with Korean traditional sauces. The samples, pork loins were cut by the shape of cube($5{\time}15{\time}5$cm) and seasoned pork with Korean traditional sauces such as soy sauce base(T1), red pepper sauce base(T2), and soybean sauce base(T3) in the same proportion of meat seasonings, respectively. The seasoned samples were stored, at $1{\pm}1^{\circ}C$ during 28 days. Citric acid and fumaric acid were higher after 14 days of storage for the treatments, seasoned pork with red pepper sauce had higher compared to other treatments. While propionic acid and lactic acid were higher in seasoned pork with soybean sauce compared to other treatments. Free amino acids was higher in seasoned pork with soybean and red pepper sauce compared to seasoned pork with soy sauce. In all treatments, free amino acids was slightly increased with aging periods. 5'-inosine monophosphate(IMP) was decreased, whereas inosine was increased with increase of aging time. Inosine was higher in seasoned pork with soybean and red pepper sauce compared to seasoned pork with soy sauce. In sensory evaluation, aroma, flavor, tenderness and juiciness were increased with aging period increased in all treatments.

• KSBB Journal
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• v.10 no.5
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• pp.533-539
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• 1995

An autolytic system based on a thermally inducible phage lambda, λHL1, has been applied for the recovery of poly(3-hydroxybutyrate) [PHB] from a recombinant Escherichia coli XL1-Blue, harbouring a plasmid (pSYL105) containing the Alcaligenes eutrophus PHB biosynthesis genes. The lytic capability ofλHL1 was evaluated in flask culture for both lysogens, XL1-Blue (λHL1) and XL1-Blue (λHL1, pSYL105). When the optical density of culture at 600nm(OD600) reached 0.2, cell lysis was induced by increasing the temperature from $30^{\circ}C$ to $42^{\circ}C$. Most cells of XL1-Blue ($\lambda$HL1) were lysed by the autolytic system in an hour after the thermal induction, while the lytic efficiency was slightly lower for XLl-Blue (λHL1, pSYL105). The existence of pSYL105 in cells seemed to inhibit, to some extent, the lytic capability of λHL1 even at low PHB content. The lylic efficiency remarkably decreased as the induction was delayed to allow PHB accumulation. When a chemical induction using 2% (v/v) chloroform was introduced after an hours of thermal induction, we could obtain a good lytic efficiency.

• Korean Journal of Agricultural Science
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• v.26 no.2
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• pp.39-48
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• 1999

This study was carried out to investigate the difference and genetic similarity at the level of molecular genetics. Genomic DNA was extracted from blood of Holstein, Korean cattle, Charolais, and hybrid between Korean cattle and charolais and RAPD(random amplified polymorphic DNAs) was analyzed by PCR(polymerase chain reaction). After genetic similarity value from different breeds are analyzed, genetic similarity was estimated by UPGMA(unweighted pair-group method using average). The results obtained from this study can be summarized as follows: 1. When genomic DNA which was extracted from different breeds was subjected to electrophoresis on 1.5% agarose gel, bigger than 12.2kb was appeared. Ratio by absorbance of $A_{260}/A_{280}$ was 1.75~2.10, indicating that genomic DNA was quite pure for RAPD analysis. 2. Different band patterns by RAPD were appeared according to the breeds in cattle. The best primer used to distinguish Holstein from other breeds was 5'-GAC CGC TTG T-3'. 3. A 340bp fragment was amplified in $33.0^{\circ}C$ of annealing temperature for the Holstein and Charolais breeds, but any amplification was not occurred in this annealing temperature for Korean cattle and hybrid. In addition, a 340bp fragment was amplified in $37.5^{\circ}C$ of annealing temperature for the Holstein and Korean cattle, but any amplification was not occurred in this annealing temperature for Charolais and hybrid. For the reaction of PCR. $37.5^{\circ}C$ and $33.0^{\circ}C$ of annealing temperature was shown to be best for genetic marker identification from Holstein, Charolais, and hybrid between Korean cattle and Charolais. 4. When genetic similarity from different breeds are analyzed at the both temperature of $33.0^{\circ}C$ and $37.5^{\circ}C$, the genetic similarity value of Holstein and Korean cattle, Holstein and Charolais, Korean cattle and Charolais, and Korean cattle and hybrid were 0.666~0.777, 0.615~0.666, 0.400~0.461 and 0.857~0.888, respectively. 5. It could be concluded that different breeds are capable of distinguishing by RAPD used random primer 5'-GAC CGC TTG T-3', genetic similarity from different breeds was appeared the higher genetic similarity value of Korean cattle and Charolais than that of Holstein between Korean cattle and Charolais by UPGMA.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.857-863
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• 1992

Acid type saturated Weston cells that can be used as the standard of electromotive force unit were constructed and their characteristics in a specially designed enclosure were evaluated. Cadmium sulfate was purified by recrystallization under vaccum. Mercurous sulfate with dispersed mercury and the exact composition of cadmium amalgam were obtained by means of electrolysis. The enclosure was constructed using a commercial circulator. Temperature of the enclosure was only drifted in the range of ${\pm}$5 mK in the case of extreme change of room temperature. The electromotive force of standard cells was measured over the temperature range of 5∼${\sim} 30^{\circ}C$. The standard deviation of the electromotive forces was about 1 ppm.