• Korean Journal of Food Science and Technology
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• v.22 no.7
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• pp.812-816
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• 1990

This study describes the sorbitol production with permeabilized cells of Zymomonas mobilis immobilized in Ca-alginate. Toluene treated cells lose activity of glucose-fructose oxidoreductase due to the leaking of enzyme from the cells. To prevent this leakage, the permeabilized cells were treated with 0.25% glutaraldehyde by stirring for 1 h at room temperature. A continuous process with glutaraldehyde treated cells was developed and no significant reduction in the degree of conversion occurred during 210 h operation. The productivities were estimated to be about $7.2{\sim}7.5\;g/l-h$ for sorbitol at dilution rate $0.18\;h^{-1}$.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.345-350
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• 2006

This study investigated the removal of recalcitrant organics in dyeing wastewater using a fluidized bed reactor(FBR) that contained cell-immobilized pellets. The pellets were manufactured and condensing the gel phase by mixing PEG-polymer and cells to form micro-porous PEG-polymer pellets whose size were ${\Phi}\;4mm{\times}H\;4mm$ on average. An industrial activated sludge without any pre-adaptation was used for the cell immobilization because it gave an equivalent removal efficiency to a pre-adapted sludges. The feed was obtained from an effluent of a biological treatment plant, which contained $SCOD_{Cr}$ of 330 mg/L and $SBOD_5$ of 20 mg/L. The $SCOD_{Cr}$ removal efficiency was over 45% and the effluent $COD_{Mn}$ concentration was less than 100 mg/L at HRTs from 6 to 24 hrs. The optimum HRT in the FBR was determined as 12 hrs considering the removal efficiency and cost. When a raw wastewater containing 768 mg/L of $COD_{Cr}$ was fed to the FBR, the effluent $COD_{Cr}$ concentration increased only slightly, giving a 70% of $COD_{Cr}$ removal or a 97% of $BCOD_5$ removal. This indicated that the FBR had an excellent capability of biodegradable organics removal also. In conclusion, the FBR could be applied to textile wastewater treatment in place of an activated sludge process.

• Journal of Microbiology and Biotechnology
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• v.30 no.2
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• pp.244-247
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• 2020

We have expressed extracellular poly(3-hydroxybutyrate) (PHB) depolymerase of Ralstonia pickettii T1 on the Escherichia coli surface using Pseudomonas OprF protein as a fusion partner by C-terminal deletion-fusion strategy. Surface display of depolymerase was confirmed by flow cytometry, immunofluorescence microscopy and whole cell hydrolase activity. For the application, depolymerase was used as an immobilized catalyst of enantioselective hydrolysis reaction for the first time. After 48 h, (R)-methyl mandelate was completely hydrolyzed, and (S)-mandelic acid was produced with over 99% enantiomeric excess. Our findings suggest that surface displayed depolymerase on E. coli can be used as an enantioselective biocatalyst.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1250-1256
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• 2011

In this study, Bacillus licheniformis cells were immobilized by entrapment in calcium alginate beads and were used for production of alkaline protease by repeated batch process. In order to increase the stability of the beads, the immobilization procedure was optimized by statistical full factorial method, by which three factors including alginate type, calcium chloride concentration, and agitation speed were studied. Optimization of the enzyme production medium, by the Taguchi method, was also studied. The obtained results showed that optimization of the cell immobilization procedure and medium constituents significantly enhanced the production of alkaline protease. In comparison with the free-cell culture in pre-optimized medium, about 7.3-fold higher productivity was resulted after optimization of the overall procedure. Repeated batch mode of operation, using optimized conditions, resulted in continuous production of the alkaline protease for 13 batches in 19 days.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.1
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• pp.67-71
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• 2001

Most of the Cyclodextrin glucanotransferase (Gtases) which have been produced from B. subtilis were found to be excreted from the cells during cultivation. Immobilized whole cell CGTase from B. subtilis was prepared by encapsulating the broth solution which had been concentrated ten times with a rotary vacuum evaporator. Cyclization activity of CGTase was reduced by about 10% during the concentrating process, however, its transglycosylation activity, to convert xylitol to glucosyl-xylitol, using dextrin as glucosyl donor, increased by a factor of 3 or 5.

• Polymer(Korea)
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• v.36 no.5
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• pp.586-592
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• 2012

Iron oxides ($Fe_3O_4$) are metabolically secreted after endocytosed by cells, indicating no cytotoxicity. Therefore, they are widely used as a contrast agent before photographing of magnetic resonance imaging. In this study, iron oxide nanoparticles are synthesized by the co-precipitation method and subsequently immobilized with a homing peptide (AP), which specifically interacts with interleukin-4 receptor located on the membrane of endothelial and bladder cancer cells. The size of AP-immobilized iron oxide particle is about 39 nm. Intracellular uptake of the AP-immobilized iron oxide nanoparticles was investigated using bladder cancer cells and fibroblasts as the control. As the result, the nanoparticles are specificially uptaken by bladder cancer cells. However, the nanoparticles are not specificially uptaken by fibroblast. It could be said that the AP-immobilized iron oxide nanoparticles have a potential to be used as a contrast agent for early diagnosis of cancer.

• Applied Biological Chemistry
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• v.38 no.4
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• pp.308-312
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• 1995

The effects of nitrogen, phosphate in modified B5 medium and cell immobilization on cell growth and taxol production were investigated using cell cultures of Taxus cuspidata. The ratio of nitrate to ammonium was found to be an important parameter. The ratio of 1 increased taxol production 10-fold, compared to the original ratio of 20 in modified B5 medium. Reducing phosphate concentration inhibited cell growth, but increased taxol production noticeably. Immobilized cells produced a taxol concentration of ${\sim}120\;g/l$

• Toxicological Research
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• v.25 no.4
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• pp.231-235
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• 2009

Trace lead detection for cyclic voltammetry (CV) and square-wave (SW) stripping voltammetry was performed using mercury immobilized onto a carbon nanotube electrode (HNPE). Using the characteristics of mercury and the catalytic carbon nanotube structure, a modified technique, the $0.45{\mu}g/l$ detection limit of lead ion was attained. The developed method can be applied to pond water, fish tissue, plant tissue, and in vivo direct assay.

• Journal of Life Science
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• v.17 no.12
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• pp.1641-1648
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• 2007

Yippee-like proteins, which have been identified as the homolog of Drosophila yippee protein containing a zinc-finger domain, are known to be highly conserved among eukaryotes. However, their functional roles are still poorly understood. Recently we initiated ordered differential display (ODD)-polymerase chain reaction (PCR) to isolate genes of which expressions are altered following activation of human T cells. On the ODD-PCR image, one PCR-product detected in unstimulated T cells was not detectable at the time when the activated T cells traversed near $G_1/S$ boundary following activation by immobilized anti-CD3. Cloning and nucleotide sequence analysis revealed that the PCR-product was yippee-like 5 (YPEL5) gene, which was known as a human homolog of the Drosophila yippee gene. Northern blot analysis confirmed the amount of ${\sim}2.2$ kb YPEL5 mRNA expression detectable in unstimulated T cells was sustained until 1.5 hr after activation and then rapidly declined to undetectable level by 5 hr. Ectopic expression of YPEL5 gene in human cervix epitheloid carcinoma HeLa cells caused a significant reduction in cell proliferation to the level of 47% of the control. Expression of GFP-YPEL5 fusion protein in HeLa cells showed its nuclear localization. These results demonstrated that the expression level of human YPEL5 mRNA was negatively regulated in the early stage of T cell activation, and suggested that YPEL5 might exert an inhibitory effect on the cell proliferation as a nuclear protein.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.718-722
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• 2015

Techniques for immobilizing effective enzymes on nanoparticles for stabilization of the activity of free enzymes have been developing as a pharmaceutical field. In this study, we examined the effect of three different pH conditions of phosphate buffer, as a dissolving solvent for lysosomal enzymes, on the direct immobilization of lysosomal enzymes extracted from Hen's egg white and Saccharomyces cerevisiae. Titanium(IV) oxide (TiO₂) nanoparticles, which are extensively used in many research fields, were used in this study. The lysosomal enzymes immobilized on TiO₂ under each pH condition were evaluated to maintain the specific activity of lysosomal enzymes, so that we can determine the degree of melanin treatment in lysosomal enzymes immobilized on TiO₂. We found that the immobilization efficiency and melanin treatment activity in both lysosomal enzymes extracted from Hen's egg white and S. cerevisiae were the highest in an acidic condition of phosphate buffer (pH 4). However, the immobilization efficiency and melanin treatment activity were inversely proportional to the increase in pH under alkaline conditions. In addition, enhanced immobilization efficiency was shown in TiO₂ pretreated with a divalent, positively charged ion, Ca²⁺, and the melanin treatment activity of immobilized lysosomal enzymes on TiO₂ pretreated with Ca²⁺ was also increased. Therefore, this result suggests that the immobilization efficiency and melanin treatment activity of lysosomal enzymes can be enhanced according to the pH conditions of the dissolving solvent.