• Microbiology and Biotechnology Letters
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• v.20 no.6
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• pp.681-686
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• 1992

In the conversion of D.L-2-amino-$\Delta^2$-thiazoline-4-carboxylic acid(D,L-ATC) to L-cysteine using Pseudomonas sp. CU6. the effects of surfactants on whole cells and the stabilities of cellfree enzyme solution and continuous reactor packed with immobilized whole cells were investigated. The enzymatic reaction was little accomplished by whole cells without adding surfactants, whereas it was well carried out with SDS or Triton X-loo comparable to the case using cell-free enzyme solution. Enzyme activity of the cell-free solution was lost by 50% after 7 hours of storage at $30^{\circ}C$, but not at all under an anaerobic condition by sparging nitrogen gas. On the other hand. effect of nitrogen gas did not appear in a continuous reactor using immobilized whole cells, and hydroxylamine, an inhibitor of L-cysteine desulfhydrase, lowered the enzyme stability.

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.695-703
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• 2006

The dissolved oxygen level of any cell culture environment has a critical effect on cellular metabolism. Specifically, hypoxia condition decreases cell viability and recombinant protein productivity. In this work, to develop CHO cells producing recombinant protein with high productivity, mammalian expression vectors containing a human tissue-type plasminogen activator (t-PA) gene with hypoxia response element (HRE) were constructed and stably transfected into CHO cells. CHO/2HRE-t-PA cells produced 2-folds higher recombinant t-PA production than CHO/t-PA cells in a $Ba^{2+}-alginate$ immobilized culture, and 16.8-folds in a repeated batch culture. In a non-aerated batch culture of suspension-adapted cells, t-PA productivity of CHO/2HRE/t-PA cells was 4.2-folds higher than that of CHO/t-PA cells. Our results indicate that HRE is a useful tool for the enhancement of protein productivity in mammalian cell cultures.

• Macromolecular Research
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• v.17 no.7
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• pp.458-463
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• 2009

Polyurethane (PU) is widely used as a cardiovascular biomaterial due to its good mechanical properties and hemocompatibility, but it is not adhesive to endothelial cells (ECs). Cell adhesive peptides, GRGDS and YIGSR, were found to promote adhesion and spreading of ECs and showed a synergistic effect when both of them were used. In this study, a surface modification was designed to fabricate an EC-active PU surface capable of promoting endothelialization using the peptides and poly(ethylene glycol) (PEG) spacer, The modified PU surfaces were characterized in vitro. The density of the grafted PEG on the PU surface was measured by acid-base back titration to the terminal-free isocyanate groups. The successful immobilization of pep tides was confirmed by amino acid analysis, following hydrolysis, and contact angle measurement. The uniform distribution of peptides on the surface was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). To evaluate the EC adhesive property, cell viability test using human umbilical vein EC (HUVEC) was investigated in vitro and enhanced endothelialization was characterized by the introduction of cell adhesive peptides, GRGDS and YIGSR, and PEG spacer. Therefore, GRGDS and YIGSR co-immobilized PU surfaces can be applied to an EC-specific vascular graft with long-term patency by endothelialization.

• Macromolecular Research
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• v.13 no.5
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• pp.446-452
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• 2005

The interactions between the surface of scaffolds and specific cells play an important role in tissue engineering applications. Some cell adhesive ligand peptides including Arg-Gly-Asp (RGD) have been grafted into polymeric scaffolds to improve specific cell attachment. In order to make cell adhesive scaffolds for tissue regeneration, biodegradable nonporous poly(L-lactic acid) (PLLA) films were prepared by using a solvent casting technique with chloroform. The hydrophobic PLLA films were surface-modified by Argon plasma treatment and in situ direct acrylic acid (AA) grafting to get hydrophilic PLLA-g-PAA. The obtained carboxylic groups of PLLA-g-PAA were coupled with the amine groups of Gly-Arg-Asp-Gly (GRDG, control) and GRGD as a ligand peptide to get PLLA-g-GRDG and PLLA-g-GRGD, respectively. The surface properties of the modified PLLA films were examined by various surface analyses. The surface structures of the PLLA films were confirmed by ATR-FTIR and ESCA, whereas the immobilized amounts of the ligand peptides were 138-145 pmol/$cm^2$. The PLLA surfaces were more hydrophilic after AA and/or RGD grafting but their surface morphologies showed still relatively smoothness. Fibroblast adhesion to the PLLA surfaces was improved in the order of PLLA control

• Journal of Korean Society of Environmental Engineers
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• v.30 no.4
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• pp.446-452
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• 2008

This study was conducted to research the biosorption characteristics using algae, Spirulina platensis, for the removal of Pb and Cu ions in wastewater. Both of free algal cell and immobilized algae by Ca-alginate were used as bioadsorbent, and experiment was proceed in batch reactor for Pb and Cu ions removal, respectively. In the biosorption of Pb and Cu ions by free Spirulina platensis cell, the adsorption equilibrium reached within 20 minute. The higher adsorbed amount of Pb and Cu was shown as increasing of initial concentration of Pb and Cu, and pH of solution, respectively, and the optimum pH was 4.5$\sim$5.0. Under the conditions of initial concentration of Pb or Cu are 200 mg/L, the maximum amounts of Pb and Cu adsorbed to the unit weight of Spirulina platensis were 86.43 and 57.02 mg/g, respectively, and these values were 1.94 and 1.48 times higher than those of activated carbon under same conditions, respectively. The biosorption kinetics of Pb and Cu ions by free Spirulina platensis cell fitted very well to the Freundlich and Langmuir isotherm. The maximum amount of Pb or Cu adsorbed to the unit mass of adsorbent by the Langmuir isotherm($q_{max}$) represented as 95.24 and 62.50 mg/g, respectively. The FT-IR results of free Spirulina platensis biomass showed that biomass has different functional groups and these functional groups are able to react with metal ions in aqueous solution. In the biosorption of Pb and Cu ions by Ca-alginate immobilized algae Spirulina platensis, the adsorption equilibrium reached within 40 min. and observed a little diffusion limitation differed from the free algal cell adsorption.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.2
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• pp.111-116
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• 1991

The effective p.eduction of 5'-GMP(5'-Guanylic acid) by enzymatic conversion of 5'-XMP(5'-Xanthyic acid) was investigated. The Iyophilized Brevibacterium ammoniagenes ATCC 19216 which were used as the XHP aminase source, was immobilized by entrapping in K-carrageenan, agar, polyacrylamide or Ca-alginate. $3\%$ K-carrageenan was selected as the most suitable matrix. In the production of 5'-GMP using the free cells of 3. ammoniagenes ATCC 19216, the optimum conditions were $42^{\circ}C$, PH 7.0, 100mg/ml glucose, 120mg/ml cell ,8mg/ml $MgSO_4\cdot7H_2O$, 5mg/ml POESA, 5mg/ml phytic acid. Under the conditions, $94.5\%$ of 5'-GMP was converted within 8 hours. In the production of 5'-GMP using the immobilized whole cells of B. ammoniagenes ATCC 19216, the optimum conditions were $37^{\circ}C$, pH 7.5, 50mg/ml glucose, 1mg/ml $KH_2PO_4$, 10mg/ml phytic acid, 60mg/ml cell, 8mg/ml $MgSO_4\;\cdot\;7H_2O$, 5mg/ml POESA. Under the conditions, $64.7\%$ of 5'-GMP was converted within 40 hours.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.84-84
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• 2013

FcBP consisting of 13 amino acids specifically binds to Immunoglobulin G Fc domain. Initially, we utilized this peptide for preparation of antibody chip as a PEG composite for enhanced solubility. After then, the peptide conjugate was immobilized on agarose resin, resulting in highly efficient affinity column for antibody purification. The efficiency was comparable to commercial Protein A column. Recently, this peptide was conjugated with cell penetratingpeptide (CPP) on a backbone of GFP, affording antibody transducer, which carries antibody into live cells by simple mixing of antibody and the transducer in cell culture media. Antibody transduction into cells was monitored by live cell imaging. More recently, the FcBP was fused to ferritin cage, which consists of 24 ferritin protein molecules. The FcBP-ferritin cage showed greatly increased binding affinity to human IgG. Its binding was analyzed by QCM and SPR analysis. Finally, it was selectively delivered by Herceptin to SKBR3, a breast cancer cell, over MCF10A, non-tumorigenic cells.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.1
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• pp.41-45
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• 2004

A phosphate solubilizig bacterium, Pantoea agglomerans, was isolated from rhizosphere soils collected from Chungbuk area. A greenhouse experiment was conducted to study the effect of combined application of rock phosphate and P. agglomerans inoculation on plant growth and phosphate accumulation of rice (Oryza sativa L.). Apart from control that received no inputs, six treatments were planned as follows; 1) seed bacterization, 2) free cell inoculation and 3) bacteria immobilized beads inoculation, individually and in combination with 1 and 2.5 g of rock phosphate per pot. The results showed that plant growth and phosphate uptake were significantly enhanced as a result of bacterial inoculation. Bacterial inoculation in the form of immobilized beads and 1 g of rock phosphate was found to affect positively the rice plant growth and phosphorus accumulation than other treatments. The available phosphate concentration of the pot mixture also found improved as a result of P. agglomerans inoculation. A positive correlation was observed between the phosphate concentration in the pot mixture and phosphate accumulation in plant.

• Microbiology and Biotechnology Letters
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• v.28 no.3
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• pp.172-179
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• 2000

Bretlanomyces C!tstersii Hl-39 mutant was immobilized with various caniers. Immobilized mutant Hl-39 produced more ethanol and showed higher productivity and cell concentration than those of free 81-39 in 3.4% hydrolyzate of wood-chips at different temperatures ($37^{\circ}C$, $40^{\circ}C$ and $43^{\circ}C$). At $37^{\circ}C$, ethanol concentration produced by mutant H1-39 immobilized in Ca-alginate and ARG(l % Ca-alginate, 1.67% bentonite, 0.33% glutaraldehyde) bead were higher than those produced by the other earners (ACG ; 1 % CaHalginate. ] .67% celite R-634 , 0.33% glutaraldehyde, ABP ; 1 % Ca-alginate. 1.67% bentonite, 0.33% pectin. ACP: 1 % Ca-alginate, ] .67% celiLe R-634, 0.33% pecLin). The highest value of productivity(l.23 ) was obtained by using ABG beads. At $40^{\circ}C$, ethanol conccntration and productivity obtained by ABC beads ,>,"ere 15.2 glL and 0.84 gl L.h, respectively, which showed the highest value compared to other carriers. Particularly, productivity of ilmnobilized ceIl was increased up to 90% as compared to that offree cell. On the other hand, ABP(l % Ca-alginate+L67% bentonile+O.33% pectin) beads gave the best resulLs at $43^{\circ}C$ for production of ethanol and productivity, which were 13.8 g!l and 0.77 g/l h, respectively.ively.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.468-472
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• 2003

Recently, genetic engineering techniques have been used to display various heterologous peptides and proteins (enzyme, antibody, antigen, receptor and fluorescence protein, etc.) on the yeast cell surface. Living cells displaying various enzymes on their surface could be used repeatedly as 'whole cell biocatalysts' like immobilized enzymes. We constructed a yeast based whole cell biocatalyst displaying T. reesei cellobiohydrolase I (CBH I ) on the cell surface and endowed the yeast-cells with the ability to degrade cellulose. By using a cell surface engineering system based on ${\alpha}-agglutinin,$ CBH I was displayed on the cell surface as a fusion protein containing the N-terminal leader peptide encoding a Gly-Ser linker and the $Xpress^{TM}$ epitope. Localization of the fusion protein on the cell surface was confirmed by confocal microscopy. In this study, we report on the genetic immobilization of T. reesei CBH I on the S. cerevisiae and hydrolytic activity of cell surface displayed CBH I.