• KSBB Journal
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• v.7 no.1
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• pp.79-83
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• 1992

The characteristics of Erwinia rhapontici cells with $\alpha$-glucosyltransferase activity immobilized in Ca-alginate beads and the performance of two different types of reactor-stirred tank reactor(STR) and packed bed reactor(PBR)-charged with these immobilized cells to produce palatinose from sucrose were investigated. The optimal pH(5.5-6.0) and temperature($30-35^{\circ}C$) showed no appreciable difference between free and immobilized cells. The apparent Km value of the immobilized cells(0.28M) was approximately two times higher than that of free cells(0.13M) at $30^{\circ}C$. The half life of the immobilized cells was found to be 380 h with STR while much greater operational stability was achieved with PBR. Continuous operation of PBR at a space velocity of $0.2h^{-1}$ for 30 days showed only 5% loss of initial activity.

• Korean Journal of Food Science and Technology
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• v.11 no.3
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• pp.192-199
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• 1979

With cells of Streptomyces spp K-45 isolated from soil, the immobilization of glucose isomerase by a series of treatments ; heat, carefully manipulated drying, extrusion with a thickening agent, and glutaraldehyde-induced crosslinking, was presented. This was aimed to obtain a mechanically stable form of whole cell containing glucose isomerase. The resulted pellet form had a good mechanical strength, compared with a commercial product, and showed 26 % of the activity recovery. The specific activity was 48.1 units per g of the dry material. The immobilized glucose isomerase generally showed properties similar to those of the soluble enzyme ; optimal pH at $7.5{\sim}9.0$, optimal temperature at $80{\sim}85^{\circ}C$, activation energy of 10.9 kcal/mole, and $K_m$ for glucose of 10.9M. The immobilized enzyme was very thermostable and pH stable.

• Korean Journal of Food Science and Technology
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• v.12 no.4
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• pp.299-304
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• 1980

By using whole cells of Leuconostoc oenos ML-34 immobilized in polyacrylamide gel, deacidification of grape juice and wine was attempted. The immobilization did not destroy the original malo-lactic fermentation ability of the cells. However, the speed of malic acid decomposition by the immobilized cells was slow due to the slow transportation of the substrate through the gel layer. By reducing malic acid content in grape juice to a desired degree one may control the level of acid taste in wine fermented with the treated grape juice.

• KSBB Journal
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• v.8 no.2
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• pp.185-191
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• 1993

Highly stable $O_2$-evolving cells and thylakoid membranes have been obtained from the cyanobacterium, Synechococcus PCC7002, by immobilization with polyvinylalcohol(PVA). The absorption peak showed the blue-shift of about 3 nm after immobilization of intact cells and thylakoid membranes as well as isolation of thylakoid membranes. Photosynthetic electron transport activities, especially PS II activity showed greater stability in the PVA-immobilized cells and thylakoid membranes when stored at $4^{\circ}C$ than in those at $25^{\circ}C$. When the cells were threated at higher temperature, the level of Fo and Fv increased. After imobilization, however, Fo showed no change. This suggests that the immobilization can protect against the damages of PS II complex, especially a water-spiliting system, by heat treatment.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.902-907
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• 1998

In this study the anaerobic degradation of nitrate by in GFM (gel and foam matrix) and bead gel immobilized Paracoccus denitrificans DSM 65 in continous culture was conducted. A novel GFM immobilization system was developed in order to improve conventional system (bead). With increasing nitrate concentration in water, the nitrate reduction rate was increased. The observed maximum denitrification rate by in GFM immobilized cells was 177 mg/L h in buffered water, while that was 33 mg/L h in tap water. In comparison with bead system the reduction activity by GFM system showed $1.2{\sim}2.1$ times better. The denitrification activity was not changed after 16 days storage at $5^{\circ}C$ and also showed better activity than that of free cells or even bead immobilized cells.

• Clean Technology
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• v.4 no.1
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• pp.45-59
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• 1998

Continuous immobilized-cell culture was carried out for the production of kasugamycin, a secondary metabolite by a filamentous bacteria, Streptomyces kasugaensis, with an intention of reducing waste generation. A sporulation medium was developed for production of bulk amounts of spores, and the spores were entrapped into celite biosupports for immobilization. It was possible to effectively keep the immobilized-cells inside the reactor during the continuous culture by an efficient immobilized cell separator of decantor type on the outlet of the fermentor. Using this continuous immobilized-cell fermentor system, we investigated the effects of feed substrate and phosphate concentrations on kasugamycin production and chemical oxygen demand(COD). Comparing with the conventional suspended-cell batch culture, the kasugamycin productivity was observed to increase by 2.5 times, whereas COD per unit kasugamycin production decreased by 2.3 times in the continuous immobilized-cell culture. Based on these results, the continuous immobilized-cell system was considered to be a cleaner bioprocess than the conventional batch suspended-cell system.

• KSBB Journal
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• v.14 no.3
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• pp.342-350
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• 1999

Photobacterium phosphoreum was used in order to study response to heavy metal including $HgCl_2$, $CdCl_2$, $MnSO_4$ and $ZnSO_4$ in view of developing monitoring system for toxic substances. The concentrations of heavy metal causing 50% reduction($EC_{50}$) in bioluminescence intensity were determined with both free and immobilized P. phosphoreum. The bioluminescence responses were examined at various concentrations of heavy metal after 10, 20 and 30 min of exposure. The linear correlation between Gamma values and concentrations of heavy metal was obtained and $EC_{50}$ was calculated from the linear correlation. The significant inhibitory concentrations for bioluminescence emission were found to be 0.05mg/L for $HgCl_2$, 25mg/L for $CdCl_2$, 50mg/L for $MnSO_4$ and 12.5mg/L for $ZnSO_4$, respectively. The free cell and disc type were shown to be more sensitive to heavy metal than cells mixed with Na-alginate or immobilized on Sr-alginate. However, the linear regression curves were derived from the Sr-alginate immobilized cells indicating the immobilization method is a useful tool for monitoring of heavy metal under more stable condition of bioluminescence.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.289-292
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• 2003

Effects of immobilization on the production of human granulocyte-macrophage colony-stimulating factor (hGM-CSF) by Nicotiana tabacum cells were investigated using alginate and polyurethane foam as immobilization matrices. Encapsulation of the cells in alginate decreased protein production by 50% compared with that of suspension culture. Maximum hGM-CSF concentration was obtained by the cells immobilizaed in polyurethane foam. High hGM-CSF production could be possible when polyurethane foam was used because of high specific production and easy immobilization for cell recycling process with high cell density.

• KSBB Journal
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• v.13 no.4
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• pp.404-410
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• 1998

Three types of adsorbents were developed by immobilizing synthetic zeolite, Philipsite-Gismonine, in alginate, cellulose acetate and dialysis membrane for the in situ removal of ammonium ion which inhibits growth and productivity of animal cells such as CHO cells producing tPA. Ammonium ion removal efficiency and cell growth promoting effect with various immobilized adsorbents were evaluated and the membrane type was selected as an optimal immobilized adsorbent. The experiments were then simulated by adding 8mM ammonium chloride and immobilized adsorbent in order to validate the removal effect under high density cell cultures. The results showed increase in maximum cell density by three times, in cell viability, and in tPA productivity by 40%. And it was found that the promoting effects were more significant in case of high ammonium ion concentration system. It was also found that the optimum addition time for immobilized adsorbents was 48 hr in the absence of ammonium chloride addition and 72 hr in the presence of ammonium chloride addition.

• KSBB Journal
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• v.21 no.5
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• pp.384-388
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• 2006

The production stability of high-yielding mutants of Streptomyces lincolnensis immobilized on celite beads was examined in repeated batch cultures. We also explored the feasibility of immobilization of vegetative mycelial cells on pre-wetted celite beads, which is practical method for cell immobilization. Repeated transfer of immobilized cells into fresh medium every 10 days increased productivity of immobilized cells and maximum concentration of lincomycin, 1007 $({\pm}256)$ mg/L, was obtained at the end of the ninth cycle. A 1.4-fold higher productivity was obtained in immobilized-cell culture than that obtained by suspended-cell culture. When pre-wetted beads were inoculated with vegetative mycelia and cultured a slightly higher amount of immobilized cells and lincomycin was obtained more than those obtained by culture of spores immobilized on dry beads. This result indicates that immobilization of mycelial cells on pre-wetted beads was readily available. This technique is simple and no additional facilities are required for cell immobilization.