• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.2
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• pp.51-54
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• 1998

It has been proved that co-cultivation of human neroblastoma cells and human fibroblast cells can enhance nerve cell growth and the production of BDNF in perfusion cultivation. In batch co-cultivation, maximum cell density was increased up to 1.76${\times}$106 viable cells/mL from 9${\times}$105 viable cells/mL of only neuroblastoma cell culture. The growth of neuroblastoma cells was greatly improved by culturing both nerve and fibroblast cells in a perfusion process, maintaining 1.5${\times}$106 viable cells/mL, which was much higher than that form fed-batch cultivation. The nerve cell growth was greatly enhance in both fed-batch and perfusion cultivations while the growth of fibroblast cells was not. It strongly implies that the factors secreted from human fibrobast cells and/or the environments of co-culture system can enhance both cell growth and BDNF secretion. Specific BDNF production rate was not enhanced in co-cultures; however, the production period was increased as the cell growth was lengthened in the co-culture case. Competitive growth between nerve cells and fibroblast cells was not observed in all cases, showing no changes of fibroblast cell growth and only enhancement of the neuroblastoma cell growth and overall BDNF production. It was also found that the perfusion cultivation was the most appropriate process for cultivating two cell lines simultaneously in a bioreactor.

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.673-677
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• 2006

A perfusion culture of transgenic Nicotiana tabacum cell suspensions, transformed to express recombinant glucuronidase (GUS), was successfully performed in a 5-1 stirred tank bioreactor. With 0.1 $day^{-1}$ of perfusion rate, the maximum dry cell weight (DCW) reached to 29.5 g/l in 16 days, which was 2.1-fold higher than the obtained in batch culture (14.3 g/l). In terms of the production of GUS, the volumetric activity could be increased up to 12.8 U/ml by using perfusion, compared with 4.9 U/ml in batch culture. The specific GUS activities in both perfusion and batch cultures were maintained at similar levels, 200-400 U/g DCW. Consequently, a perfusion culture could be a good strategy for the enhanced production of recombinant proteins in a plant cell culture system.

• Journal of Microbiology and Biotechnology
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• v.9 no.3
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• pp.323-327
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• 1999

It was shown that brain-derived neurotrophic factors (BDNFs) secreted from human neuroblastoma cells can significantly improve the growth of the neurites of PC12 nerve cells. The addition of purified BDNFs elongated the neurites of PC 12 nerve cells two to three times more than the case where the addition was not made. The perfusion rate strongly affected the change of the size of human neuroblastoma cells because the cell size decreased as the perfusion rate increased. This could also influence the productivity of BDNF from the cells. It is also important to note that the BDNF production was decreased when the cell size was reduced. BDNF production rate also decreased at a fast perfusion rate in a smaller cell size. At the relatively fast perfusion rate of 18 ml/h, the ratio of apoptotic to necrotic cells dramatically decreased, which possibly caused the decrease of BDNF production. It has been proven that the secretion of BDNF from human neuroblastoma cells was a partially growth-related process by yielding 6.2$\times l0^{-8}/g$ of BDNF/cell/h of growth related parameter and $0.48{\times}l0^{-9}/g$ of BDNF/cell/h of nongrowth-related parameter in a growth kinetic model. In addition, it was also found that the perfusion rate played a very important role in controlling the cell death mechanism.

• Microbiology and Biotechnology Letters
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• v.18 no.1
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• pp.61-65
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• 1990

Lectin related inducer can enhance IgG$_1$ production rate from murine hybridoma cells by employing step-feeding of serum free media with producing about 40 mg/$\ell$ of monoclonal antibodies. This step-feeding perfusion process also proves to be able to cutivate animal cells when serum free media can not support the growth of these cells in perfusion process, as well as to improve production rate. This process yields about 28 x 10$^{-10}$ mg of MAb/cells/h compared to 11.1 x 10$^{-10}$ and 4.0 x 10$^{-11}$ mg/cells/h for perfusion process and batch cultivation with 10% serum containing media, respectively.

• KSBB Journal
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• v.4 no.1
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• pp.34-39
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• 1989

Growth kinetics of mammalian cell, Chinese Hamster Ovalry(CHO) was investigated to effectively produce pharmaceutically important Erythropoeitin under perfusion chemostat conditions. Perfusion rate, D is correlated with total viable is to be an essential factor in controlling growth kinetic parameters under this kind of operations. It is also found that the measurement of oxygen uptake rates is a relatively accurate method to understand cell growth, in case that the traditional cell count method is no longer useful due to heavy cell clumpings. True growth yield, Ymax and maintenance coefficient, me associated with mammalian cell growth were estimated as $2.86{\times}10^8$ cells/ g of glucose and 0.0063 g of glucose/ cells/ hr, respectively.

• Journal of Microbiology and Biotechnology
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• v.12 no.3
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• pp.457-462
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• 2002

Low Electromagnetic Field (EMF) intensity in the range of $1{\mu}T\;to\;10{\mu}T$(Tesla) was found to enhance the growth of CHO cells and the production of tPA in batch and perfusion cultivations. At $1{\mu}T\;intensity,\;1.3{\times}10^7$ viable cells/ml of maximum cell density and 80 mg/l of maximum tPA production were obtained in batch cultivation, compared to $2.8{\times}10^6$ viable cells/ml and 59 mg tPA/1 in unexposed case (control). A similar trend was observed in the perfusion process, where it was possible to obtain $1.2{\times}10^7$ viable cells/ml of maximum cell density and 81 mg tPA/l of maximum tPA production by more than 80 days of cultivation. However, there was not much difference between $1{\mu}T\;and\;10{\mu}T$ in perfusion cultivation, possibly due to better environmental growth conditions being maintained by continuous feeding of fresh medium into the reactor. On the contrary, both cell growth and tPA production were severely inhibited at higher than 1 mT intensity, showing no growth at 10 mT exposure. Specific growth rate was linearly correlated to specific tPA production rate at $1{\mu}T$EMF intensity, which represents a partially growth-related relationship. It was also found that a large amount of $Ca^2+$ was released at low EMF intensity, even though the cell growth was not much affected. Low EMF intensity significantly improved both cell growth and tPA production, and tPA production seemed to be more affected than the cell growth, possibly due to the changes of cell membrane characteristics. It can be concluded that the elaboration of EMF intensity less than $10{\mu}T$ could improve cell growth and tPA production, but mainly tPA secretion through batch or perfusion process in a bioreactor.

• Microbiology and Biotechnology Letters
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• v.18 no.4
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• pp.401-405
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• 1990

Maximum specific pro-UK production rate was achieved at 15 mllmin of perfusion rate as $5.7 \times 10^{-8}$ $\mu g$/h/cell by cytostatic cultivation of human cell line 579 with DMEM and 590 FBS. As perfusion rates were increased, glutamine uptake rates were also increased but ammonium production rates remained relatively constant, which resulted in low ratio of ammonium to glutamine at high perfusion rate. Partially it quantitatively explains why the productivity is increased in perfusion cultivations. At maintenance period of 15 days by controlling metabolic process, such as 5 mM of glucose, 2 mM of gtutamine, 10% of air saturation and pH 6.2, high speecific product production rate and product yield on substrate were obtained as $12\times 10^{-8}$$\mu g$/h/cell abd 0.226 mglg of glucose, respetively. This product yield corresponds to 0.223 mg/day of productivity at 10 mllmin of perfusion rate.

• KSBB Journal
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• v.8 no.1
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• pp.17-22
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• 1993

$1.96{\times}10^{-5}$(IU/cell/hr) of specific scu-PA production rate was obtained from HEK cells in maintaining ca. $8{\times}10^{5}$(cells/ml) of maximum roll density at 10(ml/hr) of perfusion rate with recycling 20% serum free conditioned media. It can be compared to $4{\times}10^{6}$(cells/ml) of maximum cell density and $4.56{\times}10^{-4}$(IU/cell/hr) of specific production rate in cultivating cells with 1% serum containing medium. Thc conversion ratio of scu-PA to tc-UK increased up to 55% as the recycling ratio increased; however, recycling the used medium seemed to have least negative effect on cell growth. It also showed that the recycling process had definitive advantage of using serum free medium in perfusion cultivation of HEK cell line.

• Microbiology and Biotechnology Letters
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• v.19 no.5
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• pp.504-508
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• 1991

$1.85\times 10^{-10}$ (mmole/cell/h) of specific glucose consumption rate was obtained under fed-batch cultivation of recombinant mamalian ce11s with maintaining $4.7\times 10^{-7}(\mu g/ceil/h)$ of average specific erythropoeitin production rate. Higher maximum cell density was also achieved than for both cases of batch and perfusion cultivations. It proves that glutamolysis dominates metaboiic pathways at latter period of cultivation where quasi steady state was maintained. Substrate limitation of glucose concentration was estimated as 13 (mmole/l) under fed-batch conditions. while specific product production rate was decreased according to cultivation time, erythropoeitin production was increased as glucose concentration in the media increased up to 13.2 (mole/l).

• KSBB Journal
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• v.21 no.5
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• pp.336-340
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• 2006

High-density perfusion cultivation was performed to produce extracellular polysaccharide(ECP) as immunostimulating agents in suspension cell cultures of Angelica gigas Nakai. In batch culture, the maximum cell density was 16.8 gDCW/L at day 6 and 0.9 g/L of ECP was obtained at day 8. When the medium exchange was started at the fifth day after inoculation for the perfusion culture, high concentration of the cells at 23.8 gDCW/L could be achieved with continuous production of ECP. Treatments of ultrasound and Pluronic F-68 were found to be helpful for the secretion of intracellular ECP into the culture medium.