• KSBB Journal
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• 제11권1호
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• pp.30-36
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• 1996

Cyclosporin A 고정화배양과 현탁배양의 결과를 바탕으로 각각의 배양의 경우에 따른 비성장속도의 포도당에 대한 Monod 속도식을 제안하고 그에 필요 한 매개변수들을 구하였다. 고정화 배양이 현탁배양 에 비해 높은 ${\mu}m$와 낮은 Km 값을 갖는 것으로 나 타났는데 이는 고정화 균체의 우수한 활성과 기질에 대한 높은 친화도에 기 인한 것으로 보인다. 고정상 발효의 경우, 구한 매개변수들을 담체내에서의 물질 전달 및 반응속도의 정도를 나타내는 효율인자 값을 계산하는데 이용하였다. 중요한 고정화 공정변수인 담체크기, 균체부하의 정도가 기질의 확산저항에 미 치는 영향을 고려하여 효율인자값을 계산한 결과, 적절한 담체의 크기는 반경 $100 ~ 500{\mu}m$로 나타났 다. 고정화세포배양시 담체내의 균체의 균일한 분포 및 활성도의 유지를 위해서, 적정한 담체입자크기를 결정한 후 균체부하량을 조절하여 고정화 공정을 운 영하는 것이 중요한 것요로 판명되었다.

• BMB Reports
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• 제32권1호
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• pp.98-102
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• 1999

Since carbohydrates are major mediators in cell-to-cell adhesion and communication, the development of specific and strong binders against them could generate promising therapeutics. As the first step towards that goal, sugar molecules have to be immobilized to be used as an affinity matrix. The amino functionality in sugar is the most active nucleophile for the immobilization, if the amino group is available. An alternative and general method is to use the hydroxyl group as a direct nucleophile, but the quantitation of immobilized hydroxyl groups is not easily done. To overcome this limitation, we have developed a method to immobilize various isomers of monosaccharides with p-nitrophenyl groups to the beads by using their hydroxyl groups. It was found that the amount of immobilized sugar was independent of the structure of the sugar, but was dependent on the number of hydroxyl groups. We also developed a sensitive method to quantify the amount of immobilized sugar at the picomolar scale by utilizing commercially available glycosidases to release a sensitive reporter molecule, p-nitrophenol, and detect it by HPLC. This new technique would allow a facile quantitation method for immobilized sugar molecules, which could be used as the affinity matrix to develop strong binders against biologically important sugars.

• KSBB Journal
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• 제5권2호
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• pp.167-173
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• 1990

Acetobacter aceti OLS-130cell을 Ca-alginate gel에 고정시킨 후 유동층 반응기를 이용한 연속적인 식초생산 가능성을 검토하였다. Working volume 2L규모의 유동층 반응기를 사용한 회분식발효를 발효온도 3$0^{\circ}C$, 통기량 1.0VVM에서 초기 ethanol 및 초산농도 3g/l와 27g/l에서 수행한 결과 free cell인 경우 발효 80시간 경과 후 23g/l의 초산이 생성되었으며, 이때 overall productivity는 0.31g/l-hr였고, 고정화 초산균의 bead를 250g/l로 하여 발효를 수행한 결과는 발효 48시간 경과 후 23g/l의 초산이 생성되어 overal productivity는 0.48g/l-hr로서 free cell일 때보다 약 1.5배 높았다. 위의 초산발효조건에서 배양 48시간 이후부터 연속발효를 실시한 결과 배양 90일까지 초산함량 50~55g/l의 식초를 연속적으로 생산하는 것이 가능하였으며, 이때 dilution rate는 $0.12hr^-1$로서 초산생산성은 약 2.76g/l-hr로 최대값을 유지하였으며 회분식 발효에서 free cell인 경우보다는 초산생산성이 약 8.9배, 고정화 세포인 경우보다 약 5. 8배 더 높았다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.268-268
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• 2006

Due to their multipotency, stem cells can differentiate into a variety of specialized cell types, such as chondrocytes, osteoblasts, myoblasts, and nerve cells. As an alternative to mature tissue cells, stem cells are of importance in tissue engineering and regenerative medicine. Since interactions between scaffold and cells play an important role in the tissue development in vitro, synthetic oligopeptides have been immobilized onto polymeric scaffolds to improve specific cell attachment and even to stimulate cell differentiation. In this study, chondrogenic differentiation of stem cells was evaluated using surface-modified PLLA scaffolds, i.e., either hydrophilic acrylic acid (AA)-grafted PLLA or RGD-immobilized one. Porous PLLA scaffolds were prepared using a gas foaming method, followed by plasma treatment and subsequent grafting of AA to introduce a hydrophilicity (PLLA-PAA). This was further processed to fix RGD peptide to make an RGD-immobilized scaffold (PLLA-PAA-RGD). Stem cells were seeded at $1{\times}10^{6}$ cells per scaffold and the cell-PLLA constructs were cultured for up to 4 weeks in the chondrogenic medium. Using these surface-modified scaffolds, adhesion, proliferation, and chondrogenic differentiation of stem cells were evaluated. The surface of PLLA scaffolds turned hydrophilic (water contact angle, 45 degrees) with both plasma treatment and AA grafting. The hydrophilicity of RGD-immobilized surface was not significantly altered. Cell proliferation rate on the either PLLA-PAA or PLLA-PAA-RGD surface was obviously improved, especially with the RGD-immobilized one as compared to the control PLLA one. Chondrogenic differentiation was clearly identified with Safranin O staining of GAG in the AA- or RGD-grafted PLLA substrates. This study demonstrated that modified polymer surfaces may provide better environment for chondrogenesis of stem cells.

• KSBB Journal
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• 제11권1호
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• pp.22-29
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• 1996

고정상곰팡이를 이용하여 세포내 축적 이차대사산 물인 cyclosporin A (Cy A)를 연속적으로 생산하 기 위해 perfusion 고정상연속배양을 수행하였다. 이를 위해 균사형성 생산균주인 T. inflaum을 ce­l lite에 고정화하는 데 필요한 공정을 획기적으로 단 순화시키는 방법을 제시하였다. 교반식 Perfusion 생물반응기 (Immobilized Perfusion Reacter S System, 이후 IPRS로 표기 내에 제한유지 된 고밀 도 고정상균체는 매우 높은 희석속도($0.1hr^{-1}$)에서 도 유리세포를 생산해내는 세포생생기의 역할을 훌 륭하게 수행하였으며, IPRS의 배출구를 통해 연속 적으로 유출되는 고농도의 유리세포(1.0g/$\ell$/hr)는 이차대사 결과 세포내에 축적되는 CyA를 연속생산 하는 데 이용될 수 있었다. 이러한 IPRS공정 운영 은 고정상균체를 배양액으로부터 효과적으로 분리시 키는 decanting column의 개발로 가능했요며, 이로 인해 기존의 연속현탁배양에서 문제시되었던 높은 희석속도에서의 wash-out현상이 극복될 수 있었다. 또한 유출되는 유리세포(relesed-free cell)의 mor-phology를 원형의 conidiospore나 잘게 부서진 my­c celial cell로 구성되어 배양액의 rheology가 뉴튼유 체화될 수 있도록 IPRS공정을 운영함으로써, 기존 의 균사형성 미생물의 현탁배양시 나타나는 배양액 에서의 물질전달 감소현상이 뚜렷하게 개선될 수 있 었다. 유출되는 높은 균체생산성(1.0g/R/hr)을 감안할 때, 균주개발과 production배지의 최척화가 본 IPRS공정개발과 병행되는 경우 기존의 회분식배양 또는 연속현탁배양에 비해 훨씬 효과적 인 생산성 증 대를 기대할 수 있을 것으로 보인다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권1호
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• pp.19-22
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• 2003

The semicontinuous production of red pigment by immobilized cells of Bacillus sp. B H-99 was investigated in comparison with free cells. The red pigment produced highest productivity under the conditions of aeration of 0.2 mL/min and 2 mm diameter of gel beads by using 3.0% sodium alginate. Semicontinuous production by immobilized cells showed the highest productivity with replacement of fresh production medium in every 72 h for fourth fermentation cycle following the conditions of red pigment productivity.

• Journal of Microbiology and Biotechnology
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• 제1권2호
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• pp.130-135
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• 1991

The effects of media composition on citric acid fermentation using surface immobilized Saccharomycopsis lipolytica were studied. The use of the standard medium for these organisms resulted in rapid decrease of citric acid production and a transformation of immobilized cell morphologies from a yeast-type to a mycelium-type. When the standard medium was enriched with vitamins, trace minerals, a growth factor and ammonium to form a Vigorous Stationary Phase (VSP) fermentation type medium, relatively stable citric acid production (10 mg/lㆍh) was obtained. Using the VSP type medium, the surface immobilized cells also retained their yeast-type form.

• 한국식품영양학회지
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• 제11권3호
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• pp.319-322
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• 1998

본 실험에서는 GI 활성이 높은 alkalophilic Streptomyces sp.를 사용하여 2% $ extsc{k}$-carrageenan에 균체를 고정화 균체의 효소학적 특성을 살펴보았다. pH stability는 pH가 7.5~8.5에서 GI 활성이 가장 높았으며, reaction temperature는 7$0^{\circ}C$, Co2+는 10-3M, Mg2+는 10-3M일 때 GI 활성이 가장 높은 것으로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제5권4호
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• pp.229-233
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• 1995

Acremonium chrysogenum was immobilized in ionotropic gel beads to develop semi-continuous production of cephalosporin C (CPC). Barium alginate beads were more stable than calcium alginate or strontium alginate beads in chemically defined media. The gel stability of Ba-alginate was further increased by cross-linking with polyethyleneimine (PEI). The presence of carboxymethyl cellulose inside Ba-alginate beads did not reduce mass transfer resistance. Ba-alginate microbeads that had little diffusion limitation increased CPC production rate 1.6 fold higher than that of normal beads. CPC fermentation with immobilized cells in Ba-alginate microbeads was performed continuously for 40 days by way of repeated fed-batch operations. Mathematical modeling was developed to describe the repeated fed-batch fermentation system. Results of the computer simulation agreed well with the experimental data, which made it possible to predict an optimal feeding rate that could maximize total CPC productions.

• KSBB Journal
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• 제30권2호
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• pp.82-90
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• 2015

Plant cell immobilization can protect plant cells from shear forces and increase the stability of gene. An additional advantage of immobilization is the easiness for performing continuous culture with cell recycling. Therefore plant cell immobilization can overcome the limitations of plant cell applications. In addition, target protein should be selected from pharmaceutical proteins to get rid of low expression level problem. The enhanced production of human granulocyte-macrophage colony-stimulating factor (hGM-CSF) was investigated in immobilized Nicotiana tabacum suspension cell cultures. When the cells were immobilized in polyurethane foam, specific production of hGM-CSF was higher than that in alginate bead immobilization. Optimum continuous culture condition was the addition of 60 g/L sucrose in growth media with exchanging media every 6 day. Under the same condition, specific hGM-CSF production was 7 times higher in a 500-mL spinner flask than that in 100-mL Erlenmeyer flasks. Therefore, development of an effective immobilization process would be possible when the advantage of easy cell recycling was used. Consequently, enhanced production of target proteins could be possible in immobilized continuous cultures when the advantages of immobilization were applied.