• Journal of Applied Biological Chemistry
• /
• v.64 no.3
• /
• pp.309-316
• /
• 2021

Kaempferol 3-O-galactoside (Trifolin), a member of the flavonol group, has been reported to have anticancer effects against promyelocytic leukemia, histocytic lymphoma, skin melanoma and lung cancer. Trifolin has been extracted and used from several plants, but the extraction process is complicated and the final yield is low. Biotransformation is an alternative tool to produce high value-added chemicals from inexpensive compounds. To synthesis trifolin from naringenin, three genes (PeFLS and OsUGE-PhUGT) were introduced into Escherichia coli, respectively. In order to synthesis trifolin from naringenin, a co-culture fermentation system was established by optimizing the cell concentration, biotransformation temperature and medium, isopropyl-β-D-thiogalactoside (IPTG) concentration, substrate supply concentration, and recombinant protein induction time. The established optimal conditions for trifolin production were a 3:1 ratio of BL-UGTE to BL-FLS, induction of recombinant protein at 25 ℃ for 4 h after addition of 2.0 mM IPTG, biotransformation at 30 ℃, and supply of 300 μM naringenin. Through the optimized co-culture fermentation system, trifolin was biosynthesized up to 67.3 mg/L.

• Journal of Life Science
• /
• v.25 no.6
• /
• pp.673-679
• /
• 2015

The culture conditions needed to maximize the production of laccase from Pholiota highlandensis mycelia were investigated. Among the tested media for laccase production, Coriolus versicolor medium (CVM; 2% dextrose, 0.4% peptone, 0.6% yeast extract, 0.046% KH₂PO₄, 0.1% K₂HPO₄, 0.05% MgSO₄·7H₂O) showed the highest activity for the enzyme. Then, to optimize culture conditions for laccase activity, the influences of various carbon, nitrogen, phosphorus, and inorganic salt sources in CVM were investigated. The optimum culture medium was 2% fructose, 0.4% peptone with 0.6% yeast extract, 0.05% NaH₂PO₄, and 0.05% MgSO₄·7H₂O as carbon, nitrogen, phosphorus, and inorganic salt sources, respectively. Several aromatic compounds in the medium enhanced laccase activity to varying degrees. Guaiacol induced maximum laccase production, yielding 114.1 U/ml laccase activity after cultivation for 11 days at 25℃. The optimum pH and temperature for laccase production were 8.0 and 35℃, respectively. Native polyacrylamide-gel electrophoresis (PAGE) followed by laccase-activity staining with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as the substrate was performed to identify the presence of laccase under the optimum conditions studied. Zymogram analysis of the supernatant culture showed an enzymatic band with a molecular mass of about 90 kDa.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.9
• /
• pp.1559-1565
• /
• 2017

Naturally occurring ginsenoside F1 (20-O-${\beta}$-$\text\tiny{D}$-glucopyranosyl-20(S)-protopanaxatriol) is rare. Here, we produced gram-scale quantities of ginsenoside F1 from a crude protopanaxatriol saponin mixture comprised mainly of Re and Rg1 through enzyme-mediated biotransformation using recombinant ${\beta}$-glucosidase (BgpA) cloned from a soil bacterium, Terrabacter ginsenosidimutans Gsoil $3082^T$. In a systematic step-by-step process, the concentrations of substrate, enzyme, and NaCl were determined for maximal production of F1. At an optimized NaCl concentration of 200 mM, the protopanaxatriol saponin mixture (25 mg/ml) was incubated with recombinant BgpA (20 mg/ml) for 3 days in a 2.4 L reaction. Following octadecylsilyl silica gel column chromatography, 9.6 g of F1 was obtained from 60 g of substrate mixture at 95% purity, as assessed by chromatography. These results represent the first report of gram-scale F1 production via recombinant enzyme-mediated biotransformation.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.242-242
• /
• 2016

Magnetite, Fe3O4, is a ferrimagnet with a cubic inverse spinel structure and exhibits a metal-insulator, Verwey, transition at about 120 K.[1] It is predicted to possess as half-metallic nature, 100% spin polarization, and high Curie temperature (850 K). Cobalt ferrite is one of the most important members of the ferrite family, which is characterized by its high coercivity, moderate magnetization and very high magnetocrystalline anisotropy. It has been reported that the CoFe2O4/Fe3O4 bilayers represent an unusual exchange-coupled system whose properties are due to the nature of the oxide-oxide super-exchange interactions at the interface [2]. In order to evaluate the effect of interface interactions on magnetic and transport properties of ferrite and cobalt ferrite, the CoFe2O4/Fe3O4 superlattices on MgO (100) substrate have been fabricated by molecular beam epitaxy (MBE) with the wave lengths of 50, and $200{\AA}$, called $25{\AA}/25{\AA}$ and $100{\AA}/100{\AA}$, respectively. Streaky RHEED patterns in sample $25{\AA}/25{\AA}$ indicate a very smooth surface and interface between layers. HR-TEM image show the good crystalline of sample $25{\AA}/25{\AA}$. Interestingly, magnetization curves showed a strong antiferromagnetic order, which was formed at the interfaces.

• The Korean Journal of Malacology
• /
• v.24 no.3
• /
• pp.261-267
• /
• 2008

The tendency of metabolism in oyster, Crassostrea gigas, was investigated in relation to the water temperature and salinity. Oxygen consumption and ammonia excretion were measured and O:N ratio were calculated according to the water temperature from February 2007 to September 2008 and body size. The relationship between oxygen consumption and body weight has been examined in C. gigas. The weight-specific oxygen consumption rate (mg $O_2$/g/h) varied inversely with size. Oxygen consumption and ammonia excretion increased with an increase in water temperature. O:N ratio measured in this study ranged from 8 to 40 under ordinary sea water and the ratio was 8 at $25^{\circ}C$ and 16 at $10^{\circ}C$. This indicates that oyster mainly use the protein as the primary catabolic substrate during gametogenesis. Lower O:N ratio in winter suggests that oysters have to meet their energy demand by metabolizing protein to survive in stressful conditions such as low temperature and lack of sufficient food supply. This studies will provide the basic data for oyster culture farm in assessing the carrying capacity and sustainable management.

• Journal of Mushroom
• /
• v.10 no.1
• /
• pp.9-14
• /
• 2012

This study was carried out to investigated optimum mixing ratio of Korean natural Lindera glauca for production of functional oyster mushroom. Total nitrogen and carbon source of Lindera glauca was 0.16% and 40.9%, respectively and C/N ratio was 215. Total nitrogen source and pH of substrate mixed with Lindera glauca was 2.8~3.0 and 4.8~5.0, respectively. The contents of $P_2O_5$, CaO, MgO and $Na_2O$ were increased by increasing Lindera glauca, but there was no significant difference in $K_2O$ content. Mycerial growth was faster at Lindera glauca treatments than that of control. Yields of fruiting body was the highest at Lindera glauca 20%, and dimeter and thick of pileus were increased according to increase of Lindera glauca addition ratio. The L value of pileus was the highest at the Lindera glauca 10% during mushroom harvest, but there was no significant difference in the a-value and the b-value.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.9
• /
• pp.1279-1286
• /
• 2013

Particle size and metal species are important to both soil microbial toxicity and phytotoxicity in the soil ecosystem. The effects of CuO and ZnO nanoparticles (NPs) and microparticles (MPs) on soil microbial toxicity, phytotoxicity, and bioaccumulation in two crops (Cucumis sativus and Zea mays) were estimated in a soil microcosm. In the microcosm system, soil was artificially contaminated with 1,000 mg/kg CuO and ZnO NPs and MPs. After 15 days, we compared the microbial toxicity and phytotoxicity by particle size. In addition, C. sativus and Z. mays were cultivated in soils treated with CuO NPs and ZnO NPs, after which the treatment effects on bioaccumulation were evaluated. NPs were more toxic than MPs to microbes and plants in the soil ecosystem. We found that the soil enzyme activity and plant biomass were inhibited to the greatest extent by CuO NPs. However, in a Biolog test, substrate utilization patterns were more dependent upon metal type than particle size. Another finding indicated that the metal NP uptake amounts of plants depend on the plant species. In the comparison between C. sativus and Z. mays, the accumulation of Cu and Zn by C. sativus was noticeably higher. These findings show that metal oxide NPs may negatively impact soil bacteria and plants. In addition, the accumulation patterns of NPs depend on the plant species.

• Journal of the Korean institute of surface engineering
• /
• v.49 no.1
• /
• pp.1-13
• /
• 2016

This review deals with one of the surface modification techniques, chemical conversion coating and particularly cerium-based conversion coatings (CeCC) as a promising substitute for chromium and phosphate conversion coating on magnesium and its alloys. The CeCCs are commonly considered environmentally friendly. The effects of surface preparation, coating thickness, bath composition, and e-paint on the corrosion behavior of CeCCs have been studied on the AZ31 magnesium alloy. This review also correlates the coating microstructural, morphological, and chemical characteristics with the processing parameters and corrosion protection. Results showed that the as-deposited coating system consists of a three layer structure (1) a nanocrystalline MgO transition layer in contact with the Mg substrate, (2) a nanocrystalline CeCC layer, and (3) an outer amorphous CeCC layer. The nanocrystalline CeCC layer thickness is a function of immersion time and cerium salt used. The overall corrosion protection was crucially dependent on the presence of coating defects. The corrosion resistance of AZ31 magnesium alloy was better for thinner CeCCs, which can be explained by the presence of fewer and smaller cracks. On the other hand, maximum corrosion protection was achieved when AZ31 magnesium samples with thin CeCCs are e-painted. The e-paint layer further restricts and hinders the movement of chloride and other aggressive ions present in the environment from reaching the magnesium surface.

• Journal of Animal Science and Technology
• /
• v.51 no.2
• /
• pp.171-176
• /
• 2009

A bacterial strain producing intracellular phytase was isolated from cultivable soil near cowsheds and identified as a fluorescent Pseudomonas sp. BUN1. The BUN1 phytase, partially purified by cation and anion exchange chromatography, exhibited its optimal activity at $40^{\circ}C$ and pH 5.5. As for substrate specificity, it was very specific for phytate and showed little activity on other phosphorylated conjugates. Its activity was greatly inhibited by metal ions such as $Cu^{2+}$, $Cd^{2+}$, and $Zn^{2+}$. Addition of corn starch to PSM (phytasesynthetic medium) [0.5% sodium phytate, 0.5% $(NH_4)_2SO_4$, 0.5% KCl, 0.01% $MgSO_4\cdot7H_2O$, 0.01% $CaCl_2\cdot2H_2O$, 0.01% NaCl, 0.001% $FeSO_4\cdot7H_2O$, 0.001% $MnSO_4\cdot4H_2O$; pH 6.5] for the phytase production significantly induced its enzyme activity in comparison with other carbon sources tested.

• Archives of Pharmacal Research
• /
• v.28 no.3
• /
• pp.311-318
• /
• 2005

Oxidative stress has been reported to elevate ceramide level during cell death. The purpose of the present study was to modulate cell death in relation to cellular glutathione (GSH) level and GST (glutathione S-transferase) expression by regulating the sphingolipid metabolism. LLC­PK1 cells were treated with H$_2$O$_2$ in the absence of serum to induce cell death. Subsequent to exposure to H$_2$O$_2$, LLC-PK1 cells were treated with desipramine, sphingomyelinase inhibitor, and N-acetylcysteine (NAC), GSH substrate. Based on comparative visual observation with H202-treated control cells, it was observed that 0.5 $\mu$M of desipramine and 25 $\mu$M of NAC exhibited about 90 and $95\%$ of cytoprotection, respectively, against H$_2$O$_2$-induced cell death. Desipramine and NAC lowered the release of LDH activity by 36 and $3\%$ respectively, when compared to $71\%$ in H$_2$O$_2$-exposed cells. Cellular glutathione level in 500 $\mu$M H202-treated cells was reduced to 890 pmol as compared to control level of 1198 pmol per mg protein. GST P1-1 expression was decreased in H$_2$O$_2$-treated cells compared to healthy normal cells. In conclusion, it has been inferred that H$_2$O$_2$-induced cell death is closely related to cellular GSH level and GST P1-1 expression in LLC-PK1 cells and occurs via ceramide elevation by sphingomyelinase activation.