• Journal of the Mineralogical Society of Korea
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• v.17 no.1
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• pp.49-59
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• 2004

Organic smectite was hydrothermally synthesized by treating the opal-rich siliceous mudstone from the Pohang area with TMAOH solutions and 1:1 solutions of TMAOH+NaOH at $80^{\circ}C$ and concentrations ranging 10∼15%. Smectite was solely formed without accompanying any mineral products in case of TMAOH, whereas NaP and hydroxysodalite was synthesized together with smectite under the blending solution of TMAOH+NaOH. The synthesized smectite is identified as an organic smectite intercalating $TMA^{+}$ within its interlayer site, specifically corresponding to monmorillonite species, through mineralogical characterization by XRD, DTA, and IR analyses. The experimental results indicate that main precursor of the synthesized smectite is undoubtedly opal-CT, and the original sedimentary smectite included as considerable amounts in the mudstone seems to play a major role as Al-sources necessary far the smectite formation. Original inert components such as quartz and mica do not affect mostly to the synthesis reaction, and thus, are resultantly found as impurities in the synthetic products. These experimental results may imply that a new effective method for the low-temperature (less than $100^{\circ}C$) hydrothermal synthesis of organic smectite will be established if some Al-sources adequate for this synthetic system are available.

• Korean Journal of Microbiology
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• v.43 no.4
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• pp.341-345
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• 2007

Fifty endophytic bacteria, which produced slime around the colonies, were isolated from Pueraria roots. In particular, HDN-14, TDG-3, and TNB-3 strains, which appeared to be high viscosity producers, were selected. These strains produced high levels of polysaccharides in Puerara root medium extract. The purified polysaccharide was digested with 1N HCI and analyzed by HPLC, with glucose ($45.6{\sim}63.1%$), maltose ($14.6{\sim}23.7%$), and fructose ($17.4{\sim}23.7%$) detected as constitutive sugars. When determined by the homology relationship of the 16S rDNA sequence with the relative taxa, the HDN-14 and TNB-3 strains were closely ($99.06{\sim}99.32%$) related to the Pseudomonas $koreensis^T$ and Pseudomonas $jessenii^T$, while TDG-3 were closely ($99.48{\sim}99.74%$) related to Pseudomonas $plecoglossicida^T$, Pseudomonas $mosselii^T$, and Pseudomonas $monteilii^T$. The major cellular Pseudomonas acids are $3OH-C_{10:0}$, $2OH-C_{12:0}$, $3OH-C_{12:0}$, and $3OH-C_{12:1}$, with these strains being further differentiated in species belonging to the genus Pseudomonas.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.419-426
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• 2015

The aims of this study were to isolate spore-forming Bacillus strains that exhibit high digestibility and anti-pathogenic bacteria toward feed for calves. Total 136 spore-forming strains were isolated from finished feeds and their ingredients. Among them, 93 strains were identified as Bacillus species when analyzed by 16S rRNA sequencing. For industrial use, three strains named as Bacillus licheniformis SHS14, B. subtilis LCB7, B. amyloliquefaciens LCB10 were selected after evaluating the industrial standards that are related with heat and acid resistance, enzyme activities, and anti-pathogenic activities against Samonella dublin ATCC15480 and E. coli K99. After each culture, 3 selected strains were mixed together at 1:1:1 (v/v/v) ratio and then prepared as the mixed starter culture for feeding. The changes in microbial community were analyzed via 16S rRNA metagenomics. The initial community ratio among three strains was maintained even after manufacturing into final products. Also, in vitro, enzymatic and anti-pathogenic activities were almost same as those when cultured in single culture, and results of anti-pathogenic activities conducted with calves showed 90% activities against lincomycin, which would be indicative of a promising feed starter.

• Korean Journal of Microbiology
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• v.43 no.4
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• pp.250-255
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• 2007

The RecA protein of Deinococcus radiodurans is essential for the extreme radiation resistance of this organism. The central steps involved in recombinational DNA repair require DNA-dependent ATP hydrolysis by recA protein. Key feature of RecA protein-mediated activities is the interactions with ssDNA and dsDNA. The ssDNA is the site where RecA protein filament formation nucleates and where initiation of DNA strand exchange takes place. The effect of sequence heterogeneity of ssDNA was examined in this experiment. The rate of homopolymeric synthetic ssDNA-dependent ATP hydrolysis was constant or nearly so over a broader range of pHs. For poly(dT)-dependent ATP or dATP hydrolysis, rates were generally faster, with a broader optimum between pH 7.0 and 8.0. Activities of RecA protein were affected by the ionic environment. The ATPase activity was shown to have different sensitivity to anionic species. The presence of glutamate seemed to slimulate the hydrolytic activity. Dr RecA protein was shown to require $Mg^{2+}$ ion greater than 2 mM for binding to etheno ssDNA and the binding stoichiometry of 3 nucleotide for RecA protein monomer.

• Journal of the Korean Chemical Society
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• v.40 no.1
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• pp.44-49
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• 1996

The cadmium(Ⅱ)-carboxylate complexes of monocarboxylates and poly(acrylic acid) (PAA) in an aqueous solution were investigated using 113Cd NMR spectroscopy. From these spectral data the chemical shifts of the monocarboxylate (e.g. acetate, benzoate and propanoate) complexes of Cd(Ⅱ) were evaluated (CdL+: -22 to -24 ppm range; CdL2: -39 to -40 ppm range; L: carboxylate). The chemical shift of cadmium(Ⅱ) bound on PAA changed in value from -36.6 to -38.2 ppm when the [PAA]/[Cd] ratios were varied from 12 to 118 eq/mol at a constant pH of 6. The 113Cd chemical shift was sensitive to the change in solution pH: the chemical shift changed from 1.6 to -37.6 ppm when the pH was rasied from 1 to 6 at a constant [PAA]/[Cd] ratio of 39 eq/mol. These results show that under these conditions, the dominant species formed in solution is 1 : 2 complex (CdL2), and 1 : 1 complex (CdL+) is only formed at low pH, when polyanion concentration is low.

• Journal of the Korean Ceramic Society
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• v.42 no.3 s.274
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• pp.165-170
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• 2005

Sol-gel methods offer many advantages over conventional slip-casting, including the ability to produce ceramic membranes. They are purer, more homogeneous, more reactive and contain a wider variety of compositions. We produced ormosil sol using sol-gel process under various molecular weight of polymer species[polyethylene glycol(PEG)] in total system [Tetraethyl ortho silicate(TEOS)-polyethylene glycol(PEG)]. The properties of as-prepared ormosil sol such as viscosity and gelation time are characterized. Also, the ceramic membrane was prepared by dip-coating with synthetic sol and its microstructure was observed by scanning electron microscopy. The permeability and rejection efficiency of membrane for oil/water emulsion were evaluated as cross­flow apparatus. The ormosil sol coated membrane was easily formed by steric effect of polymer and it improved flux efficiency because infiltration into porous support decreased. Its flux efficiency was elevated about $200\;l/m^2h$ compared with colloidal sol coated membrane at point of five minutes from starting test.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.1
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• pp.34-39
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• 2007

Penaeidins are members of a special family of antimicrobial peptides existing in several species of shrimp and play a crucial role in the immunological defense of shrimp. In this study, we isolated and characterized one EST clone (penaeidin) from cDNA library of fleshy prawn Fenneropenaeus chinensis hemocytes. Amino acids sequence comparison and phylogenetic analysis with other known penaeidins revealed that our clone was completely identical to F. chinensis Penaeidin 3-2 (Accession no. ABC33920), which composed of 71 amino acids with a putative signal peptide (1-19) and a cysteine-rich domain (C-terminal part). The expression and distribution of Penaeidin 3-2 transcripts in shrimp were detected in hemocytes, hepatopancreas, and muscles, and that Penaeidin 3-2 was constitutively expressed mainly in hemocytes. The artificial infection of white spot syndrome virus to F. chinensis resulted in Penaeidin 3-2 mRNA up-regulation in hemocytes, suggesting that the possible role of Penaeidin 3-2 in host defense system of F. chinensis.

• Development and Reproduction
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• v.10 no.2
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• pp.127-133
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• 2006

[ $17\;{\alpha}-hydroxylase/17,20-lyase(P450_{C17})$ ] is the key enzyme mediating the conversion of progesterone to $17\;{\alpha}-hydroxyprogesterone$, ultimately to androstenedione during steroidogenesis. R. dybowskii's ovarian $P450_{C17}$ cDNA was cloned to understand the regulatory mechanism of ovarian steroidogenic pathway at the molecular level in amphibian. A 2.5kb cDNA clone encoding a single open-reading frame with a 519 deduced amino acid was isolated with the screening of ovarian cDNA library. This sequence contained the three highly conserved domains as seen in $P450_{C17}$ of other species. The comparison of amino acid sequence of Rana $P450_{C17}$ with other animal's $P450_{C17}$ showed relatively high identity with 76% in Xenopus, 63% in chicken, 60% in rainbow trout, and 45% in human. Phylogenic analysis also indicated that Rana $P450_{C17}$ gene was evolutionary well conserved among vertebrate. Northern analysis indicated that the two different sizes of $P450_{C17}$ transcripts with approximately 2.5 and 3.6kb were detected in ovary tissue, but not in other tissues. The expression vector of Rana $P450_{C17}$ clearly showed the $17\;{\alpha}-hydroxylase$ activity converting the exogenous progesterone into $17\;{\alpha}-hydroxyprogesterone$ in the nonsteroidogenic COS-1 cells. Therefore, Rana $P450_{C17}$ cDNA is very useful to investigate the molecular mechanism of the ovarian steroidogenesis in amphibian.

• The Plant Pathology Journal
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• v.16 no.5
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• pp.269-279
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• 2000

Alfalfa mosaic alfamoviruses(AIMV) were isolated from infected potato (Solanum tuberosum) and azuki bean (Paseolus angularis) in Korea. Two AIMV isolated from potatoes were named as strain KR (AIMV-KR1 and KR2) and AIMV isolated from azuki bean was named as strain Az (AIMV-Az). Each isolated AIMV strain was characterized by using their host ranges, symptom developments, serological relations and nucleotide sequence analysis of coat protein (CP) gene. Strains KR1, KR2, and Az were readily transmitted to 20 of 22 inoculated plant species including bean, cowpea, tomato, tobacco, and potato. AIMV-KR1 and KR2 produced the typical symptoms like chlorotic or necrotic spots in Chenopodium quinoa and Solanum tuberosum cv. Superior. AIMV-Az caused bright yellow mosaic symptom and leaf malformation in Nicotiana glauca, which were different from the common mosaic symptom caused by AIMV-KR1 and KR2. Electron microscope observation of purified virus showed bacilliform virions containing a single-stranded plus-strand RNAs of 3.6, 2.6, 2.0 and 0.9 kbp in length, respectively, similar in size and appearance to those of Alfamovirus. In SDS-PAGE, the coat protein of the two viruses formed a consistent band that estimated to be about 24kDa. The CP genes of the AIMV strains, KR1, KR2, and Az have been amplified by RT-PCR using the specific primers designed to amplify CP gene from viral RNA-3, cloned and sequenced. Computer aided analysis of the amplified cDNA fragment sequence revealed the presence of a single open reading frame capable of encoding 221 amino acids. The nucleotide and peptide sequence of viral CP gene showed that strain KR1, KR2, and Az shared highest nucleotide sequence identities with AIMV strain 425-M at 97.7%, 98.2%, and 97.2%, respectively. CP gene sequences of two strains were almost identical compared with each other. Altogether, physical, serological, biological and molecular properties of the purified virus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.11
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• pp.1507-1514
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• 2008

Cholesterol oxidase catalyses the conversion of cholesterol to 4-cholesten-3-one. This enzyme has been used for clinical assay of human serum cholesterol and for reduction of cholesterol level in foods and feeds. In order to search the microorganism which has a high extracellular and stable activity of cholesterol oxidase, soil microorganisms were screened. As a result, the one with the highest extracellular cholesterol oxidase activity was obtained and named as the BEN 115. The BEN 115 strain was identified as one of the Nocardia species based on our taxonomic studies. The cholesterol oxidase from this strain was shown to have two bands of extracellular proteins on SDS-PAGE and Western blot. Their molecular masses were estimated to be about 55 and 57 kDa, respectively. In addition, this cholesterol oxidase was considerably stable at the broad range of pH $3.5{\sim}9.5$ and at the temperature of $25{\sim}55^{\circ}C$. The optimum pH and temperature of this cholesterol oxidase were pH 5.5 and $35^{\circ}C$, respectively. The activity of extracellular cholesterol oxidase could be enhanced 1.6 to 2.0 folds by the addition of nonionic detergent such as Triton X-114, Triton X-100, or Tween-80 into the culturing broth. The substrate specificities against campesterol, sitosterol and stigmasterol were measured to be 50%, 50%, and 27%, respectively, compared to the cholesterol. These results suggest that Nocardia sp. BEN 115 may be useful as a microbial source of cholesterol oxidase production.