• Journal of Microbiology and Biotechnology
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• v.9 no.2
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• pp.227-229
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• 1999

Animal cell culture media are usually supplemented with fetal bovine serum (FBS); however, the use of FBS presents certain problems including high cost. By using an adaptation process and the addition of silkworm hemolymph, the FBS concentration can be reduced without causing a significant decrease in cell growth.

• KSBB Journal
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• v.32 no.2
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• pp.90-95
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• 2017

Mammalian cell cultures have been used extensively to produce proteins for therapeutic agent because of their ability to perform post-translational modification including glycosylation. To produce recombinant protein, many factors and parameter are considered such as media composition, host cell type, and culture process. In this study, recombinant human erythropoietin (rhEPO) producing cell line was established by using glutamine synthetase system. To reduce serum concentration in media, we compared direct adaptation with step adaptation. Cell growth was faster in step adaptation. In low-level serum media, there were insufficient glucose for cell growth. Thus, we added glucose in low-level serum media from 2 g/L to 4.5 g/L. Titer of rhEPO was higher than other conditions at 4.5 g/L of glucose. Additionally, N-methyl-D-aspartate (NMDA), 13-cis-retinal, and pluronic F-68 (PF-68) were added to enhance productivity in CHO cell cultures. In conclusion, we applied CHO cell producing rhEPO to low-level of serum in media using step-adaptation. Also, we confirmed positive effect of NMDA, 13-cis-retinal, and PF-68.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.6
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• pp.564-570
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• 2005

In the present study, the protective effects of Bcl-2 over-expression in a suspension culture (without any adaptation) and spent medium (low nutrient and high toxic metabolite conditions) were investigated. In the suspension culture without prior adaptation, the viability of the control cell line fall to 0% by day 7, whereas the Bcl-2 cell line had a viability of 65%. The difference in the viability and viable cell density between the Bcl-2 and control cell lines was more apparent in the suspension culture than the static culture, and became even more apparent on day 6. Fluorescence microscopic counting revealed that the major mechanism of cell death in the control cell line in both the static and suspension cultures was apoptosis. For the Bcl-2 cell lines, necrosis was the major mode of cell death in the static culture, but apoptosis became equally important in the suspension culture. When the NS0 6A1 cell line was cultured in spent medium taken from a 14 day batch culture, the control cell line almost completely lost its viability by day 5, whereas, the Bcl-2 still had a viability of 73%. The viable cell density and viability of the Bcl-2 cell line cultivated in fresh medium were 2.2 and 2.7 fold higher, respectively, than those of the control cultures. However, the viable cell density and viability of the Bcl-2 cultivated in the spent medium were 8.7 and 7.8 fold higher, respectively, than those of the control cultures. Most of the dead cells in the control cell line were apoptotic; whereas, the major cell death mechanisms in the Bcl-2 cell line were necrotic.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.171-173
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• 2003

Suspension culture in serum-free medium is important for the efficient large-scale culture of anchorage-dependent cells that are utilized to produce therapeutic recombinant protein(e.g., insulin, antibody, vaccine) and virus vector for therapeutic gene transfer. We developed a novel method for the suspension culture of anchorage-dependent animal cells in serum-free medium using biodegradable polymer nanospheres in this study. Poly(lactic-co-glycolic acid) (PLGA) polymer nanospheres (433nm in average diameter) were used to the culture of human embryonic kidney 293 cells in serum-free medium in stirred suspension bioreactors. The use of PLGA nanospheres promoted the aggregate formation and cell growth (3.8-fold versus 1.8-fold growth), compared to culture without nanospheres. Adaptation of the anchorage-dependent cells to suspension culture or serum-free medium is time-consuming and costly. In contrast, the culture method developed in our study does not require the adaptation process. This method may be useful for the large-scale suspension culture of various types of anchorage-dependent animal cells in serum-free medium.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.87-90
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• 1995

A process of organically bound germanium preparation was developed for healthy food using inorganic germanium adapted Saccharomyces cerevisiae. Adaptations of Saccharomyces cerevisiae against inorganic germanium were successively carried out through stepwise increase of GeO$_{2}$ concentration in order to produce high quantities of germanium bound yeast. Productivity of yeast and quantities of germanium in yeast were obtained 70.2 g/l and 9780 ppm, repectively, when adapted yeast and fed batch culture were used. Germanium taken-up yeast is to be organically bound germanium by evidence of no difference of germanium content after dialysis.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.409-412
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• 2000

In hybridoma cell culture, $NH_4\;^+$ is the most important toxic byproduct so far identified. It has been postulated that $NH_4\;^+$, which is similar to $K^+$ in size, is taken up non-specifically by the cells through a potassium transport system, and that the addition of $K^+$ to the culture medium may have a detoxifying effect of $NH_4\;^+$. Thus, in this study the effects of varying $Na^+/K^+$ ratios by adding potassium were investigated for hybridoma physiology and CHO cell morphology respectively. The possible use of potassium addition for the adaptation of CHO cells to suspension culture is discussed.

• KSBB Journal
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• v.13 no.3
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• pp.231-237
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• 1998

An attenuated Japanese encephalitis virus (JEV) clone SA-14-14-2(Vero) was obtained through successive adaptation of a primary cell adapted strain, SA-14-14-2(PDK) to Vero cell, a continuous line of monkey kidney cells. The virus titer reached above the 107 plaque forming unit (pfu) per mL of culture supernatant with 3 passages in Vero cells and was maintained close to this level in the further passages. The optimum temperature for the virus growth was $35^{\circ}C$. Growth pattern of the virus indicated that optimum time for the virus harvest is 4 days post infection and the virus accomplished rapid initial propagation even in medium containing no serum supplement. The roller bottle (RB) system and the spinner flask (SF) system using micro-carrier (Cytodex-1) for the JEV cultivation were explored. When RB, SF, and T-flask culture system were compared, there was no significant difference in virus yield. Furthermore, the results indicated that virus could be harvested multiple times from 3 days to 9 days post infection; neither severe cytopathic effect (CPE) in the infected cells nor the decrease in the titer was observed on duration of 9 days.

• Journal of Microbiology and Biotechnology
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• v.21 no.3
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• pp.243-251
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• 2011

The gene bolA was discovered in the 80's, but unraveling its function in the cell has proven to be a complex task. The BolA protein has pleiotropic effects over cell physiology, altering growth and morphology, inducing biofilm formation, and regulating the balance of several membrane proteins. Recently, BolA was shown to be a transcription factor by repressing the expression of the mreB gene. The present report shows that BolA is a transcriptional regulator of the dacA and dacC genes, thus regulating both DD-carboxypeptidases PBP5 and PBP6 and thereby demonstrating the versatility of BolA as a cellular regulator. In this work, we also demonstrate that reduction of cell growth and survival can be connected to the overexpression of the bolA gene in different E. coli backgrounds, particularly in the exponential growth phase. The most interesting finding is that overproduction of BolA affects bacterial growth differently depending on whether the cells were inoculated directly from a plate culture or from an overnight batch culture. This strengthens the idea that BolA can be engaged in the coordination of genes that adapt the cell physiology in order to enhance cell adaptation and survival under stress conditions.

• Journal of Microbiology and Biotechnology
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• v.17 no.3
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• pp.393-397
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• 2007

A Haematococcus pluvialis strain isolated from the ruins of Ephesus in Turkey was investigated as regards its adaptation to laboratory conditions and maximum growth rate. In the first stage of the experiment, the growth of H. pluvialis was compared in common culture media. Furthermore, in an effort to minimize the culture costs, the second stage of the experiment compared the growth rate in the culture medium selected in the first stage with that in commercial plant fertilizers. The results demonstrated that the maximum cell concentration of 0.90 g/l, corresponding to a growth rate of $0.150d^{-1}$, was found with an N-P-K 20:20:20 fertilizer under a light intensity of $75{\mu}mol$ photons $m^{-2}s{-1}$ on the $12^{th}$ day of cultivation.

• KSBB Journal
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• v.7 no.4
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• pp.308-316
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• 1992

Two-stage continuous culture system has been studied intensively to maximize the productivity of a cloned gene product in unstable recombinant microorganism. As an effort to optimize the two-stage process, transient behavior of the second-stage was studied theoretically as well as experimentally using Escherichia coli Kl2$\delta$Hl$\delta$trp. A mathematical model describing the transient response to a step change in dilution rate was developed based on the assumption that the adaptation rate of cell growth is proportional to the available growth potential, which is defined as the difference in dilution rates between before and after shift-up. The kinetic parameters appearing in the model equations were the dimensionless step increase in growth rate($\alpha$) and the adaptation rate constant(k). These parameters were evaluated for various dilution rates and temperatures by washout method. This relatively simple adaptation model could predict the specific growth rate of the second-stage successfully. Advantage and disadvantage of the proposed model are also discussed.