• Journal of Microbiology and Biotechnology
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• 제31권3호
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• pp.349-357
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• 2021

Monoclonal antibodies are widely used as diagnostic reagents and for therapeutic purposes, and their demand is increasing extensively. To produce these proteins in sufficient quantities for commercial use, it is necessary to raise the output by scaling up the production processes. This review describes recent trends in high-density cell culture systems established for monoclonal antibody production that are excellent methods to scale up from the lab-scale cell culture. Among the reactors, hollow fiber bioreactors contribute to a major part of high-density cell culture as they can provide a tremendous amount of surface area in a small volume for cell growth. As an alternative to hollow fiber reactors, a novel disposable bioreactor has been developed, which consists of a polymer-based supermacroporous material, cryogel, as a matrix for cell growth. Packed bed systems and disposable wave bioreactors have also been introduced for high cell density culture. These developments in high-density cell culture systems have led to the monoclonal antibody production in an economically favourable manner and made monoclonal antibodies one of the dominant therapeutic and diagnostic proteins in biopharmaceutical industry.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권3호
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• pp.189-193
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• 2001

Critical cell density (CCD), the maximum cell concentration without mutual shading in algal cultures, can be used as a new operating parameter for high-density algal cultures and for the application of the flashing light effect on illuminated algal cultures. CCD is a function of average cell volume and light illumination area. The CCD is thus proposed as an index of estimation of mutual shading in algal cultures. Where cell densities are below the CCD, all the cells in photobioreactors can undergo photosysnthesis at their maximum rate. At cell densities over CCD, mutual shading will occur and some cells in the illumination chamber cannot grow photoautotrophically. When the cell concentration is higher than the CCD, specific oxygen production rates under flashing light were higher than those under continuous light. The CCD was found to be a useful engineering parameter for the application of flashing light, particularly in high-density algal cultures.

• Journal of Microbiology and Biotechnology
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• 제21권10호
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• pp.1053-1056
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• 2011

Optimal conditions for a high cell density fermentation were investigated in a recombinant Escherichia coli producing salmosin, a platelet aggregation inhibitor. The optimized carbon and nitrogen sources were glycerol 10 g/l, yeast extract 30 g/l, and bacto-tryptone 10 g/l, yielding the dry cell weight (DCW) of 10.61 g/l in a 500 ml flask culture. The late-stage induction with 1% L-arabinose in a 5 l jar fermentor showed the highest DCW of 65.70 g/l after 27 h of the fed-batch fermentation. Around 2,200 mg/l of the protein was expressed as an inclusion body that was then refolded to obtain the active salmosin of 96 mg/l. We also confirmed the inhibitory activity against platelet aggregation of the active salmosin from the high cell density fermentation.

• 한국수소및신에너지학회논문집
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• 제30권1호
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• pp.43-48
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• 2019

This study investigates the electrochemical characteristics of the hybrid cell that combined the advantageous characteristics of Li secondary battery and supercapacitor, high energy density and high power density, respectively. Electrochemical behaviors of the hybrid cell was characterized by charge/discharge, cycle and impedance tests. The hybrid cell using Li secondary battery and supercapacitor had better discharge capacity and cycle performance than that of using Li secondary battery only. Proper design of such a hybrid cell system is expected to result in substantial benefits to the well being of the Li secondary battery. The hybrid cell involving Li secondary battery for high energy density and supercapacitor for high power density may be the possible solution for future energy storage system.

• Journal of Microbiology and Biotechnology
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• 제18권5호
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• pp.918-925
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• 2008

Controlling the light energy and major nutrients is important for high cell density culture of cyanobacterial cells. The growth phase of Anabaena variabilis can be divided into an exponential growth phase and a deceleration phase. In this study, the cell growth in the deceleration phase showed a linear growth pattern. Both the period of the exponential growth phase and the average cell growth rate in the deceleration phase increased by controlling the light intensity. To control the light intensity, the specific irradiation rate was maintained above $10\;{\mu}mol/s/g$ dry cell by increasing the incident light intensity stepwise. The final cell density increased by controlling the nutrient supply. For the control of the nutrient supply, nitrate, phosphate, and sulfate were intermittently added based on the growth yield, along with the combined control of light intensity and nutrient concentration. Under these control conditions, both final cell concentration and cell productivity increased, to 8.2 g/l and 1.9 g/l/day, respectively.

• 전력전자학회논문지
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• 제23권3호
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• pp.217-224
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• 2018

In this study, the optimal design methods of soft-switching cell for high-voltage DC-DC converter (HDC) of fuel cell electric vehicles (FCEVs) is proposed for high efficiency and high power density. The appropriate soft-switching cell for FCEVs is chosen by analyzing the losses of HDC which adopts soft-switching cell. The proposed optimal design methods for the soft-switching cell are divided into two purposes which are improvement of efficiency and power density. Two kinds of design methods enable to improve fuel efficiency and cost, respectively. The proposed design methods are validated with the experimental results based on the specification and hardware used in actual FCEVs.

• KSBB Journal
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• 제14권2호
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• pp.160-166
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• 1999

본 연구에서는 ($\beta$-carotene 생산균주인 미세조류 Dunaliella bardawil을 사용하여 batch flask에서 미세조류의 고농도세포에 관한 최적배양조건(미량원소, pH, agitation speed, nitrate, phosphate, carbon source)을 확립하고자 하였다. 미량원소는 5X 배지에서 교반하였을 때 비생장속도는 $0.0l3hr^{-l}$와 세포농도는 $4.9{\times}10^6$ cells/mL로서 IX. 3X, lOX 배지에서 배양한 것보다. 약 46%, 18%, 69% 높은 세포수율을 얻었으며 세포배양시 교반한 경우, pH는 80에서 최대 세포농도를 얻었다. 초기 nitrate ($KNO_3$)와 phosphate($KH_2PO_4$)의 영향을 조사한 결과 미세조류 생장에 중요한 영양분으로서 질소원의 주입은 매우 효과적임을 확인하였다. 또힌 탄소원으로서 250mM의 $NaHCO_3$와 $CO_2$ 가스를 동시에 사용한 배양조건이 500mM $NaHCO_3$만을 탄소원으로 사용한 실험에 비하여 32% 증가된 세포농도를 나타내었다. light는 white light의 경우 blue light보다 세포생장에 적합하였다. 질소원을 이용한 유기배양시 2회의 nitrate주입만으로써 배양 198hr에 $8.955{\times}10^6$cell/mL의 고농도의 세포를 얻었다.

• 한국세라믹학회지
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• 제36권9호
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• pp.954-964
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• 1999

The effect of fabrication variables and microstructures on the compressive strength of open cell alumina zirconia and silicon nitride ceramics fabricated by polymeric sponge method was investigated. Bulk density and compressive strength of open cell ceramics were mainly affected by coating characteristics of ceramic slurry on polymeric sponge that controlled a shape thickness and defect of the struts. Sintering temperature was optimized for enhancement of strut strength and compressive strength of open cell ceramics. Relative density and compressive strength behaviors were relatively well matched with the predicted values. Open cell ceramics of lower relative density below 0.1 prepared by first relatively well matched with the predicted values. Open cell ceramics of lower relative density below 0.1 prepared by first coating of ceramic slurry had thin triangular prismatic struts that were often broken or longitudinally cracked. With an application of second coating of slurry shape of struts was transformed into thickner cylindrical one and defects in struts were healed but the relative density increased over 0.2 Open cell zirconia had both the highest bulk density and compressive strength and alumina had the lowest compressive strength while silicon nitrides showed relatively high compressive strength and the lowest density. Based upon the analysis open cell silicon nitride was expected to be one of potential structural ceramics with light weight.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권2호
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• pp.123-129
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• 2000

A high cell density culture system for the anchorage dependent CHO cells was developed based on the combination of in removal of ammonium ion and microcarrier culture system, and semi-fed-batch feeding of glucose and glutamine was employed to the developed culture system. The glass bead was selected as an optimum microcarrier in terms of cell growth. An ammonium ion selective zeolite, Phillipsite-Gismondine, was packed in a dialysis menium ion. The semi-fed-batch operation was employer to the novel culture system for the high density cell culture, and the results showed the cell growth was improved by 32% and tPA productivity by 250%.

• 한국미생물·생명공학회지
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• 제13권3호
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• pp.209-212
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• 1985

산소 투과율이 좋은 silicone tube안쪽에 nutrient 공급을 위한 3개의 isotropic polypropylene hollow fiber 3개를 넣어 제작된 이중 실관 반응기에서 E. coli cell을 immobilization 하여 cell density와 packing characteristics를 조사해 보았다. E. coli cell들은 거의 100% Packing되어 동물조직에서 처럼 층을 이루면서 자랐고 ceil density를 측정해 본 결과 약 550g/$\ell$고농도 세포배양이 가능하였다.