• Biotechnology and Bioprocess Engineering:BBE
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• 제1권1호
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• pp.22-25
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• 1996

An Exponetial feeding strategy has been frequently used in fed-batch fermentation of recombinant E. coli. In this feeding scheme, growth yield and initial cell concentration, which can be erroneously determined, are needed to calculate the feed rate for controlling specific growth rate at the set point. The effect of the incorrect growth yield and initial cell concentration on the control of the specific growth rate was theoretically analyzed. Insignificance of the correctness of those parameters for the control of the specific growth rate was shown theoretically and experimentally.

• Journal of Microbiology and Biotechnology
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• 제6권4호
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• pp.232-237
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• 1996

Growth yield of Desulfovibrio desulfuricans M6 was measured using different substrates. The cell yield of fermentative growth on pyruvate was 6.22 g cell $mol^{-l}$ pyruvate. Since 1 ATP is available from substrate-level phosphorylation from the oxidation of pyruvate to acetate, $Y_{ATP}$ of the bacterium should be the same as $Y_{pyruvate}$ (6.22 g cell $mol^{-l}$ ATP). The cell yields of the bacterium on different electron donors were measured with sulfate as the electron acceptor. Cell yields on lactate, pyruvate and $H_2$ were 9.39, 13.76 and 8.45 g cell $mol^{-l}$ substrate, respectively. From these figures ATP available from electron-transport phosphorylation (ETP) of the electron donors used was calculated. ATP produced by ETP of each electron donnor were 1.71 from pyruvate, 1.51 from lactate and 1.76 from $H_2$. These values show that electrons from the oxidation of lactate to pyruvate are consumed to reduce sulfate through a reverse electron transport mechanism requiring 0.2 ATP for each pair of electrons. Based on these results, discussions are made on the electron transport mechanism in the bacterium.

• Journal of Microbiology and Biotechnology
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• 제25권7호
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• pp.1114-1118
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• 2015

Microbial fuel cells (MFCs) have gathered attention as a novel bioenergy technology to simultaneously treat wastewater with less sludge production than the conventional activated sludge system. In two different operations of the MFC and aerobic process, microbial growth was determined by the protein assay method and their biomass yields using real wastewater were compared. The biomass yield on the anode electrode of the MFC was 0.02 g-COD-cell/gCOD-substrate and the anolyte planktonic biomass was 0.14 g-COD-cell/g-COD-substrate. An MFC without anode electrode resulted in the biomass yield of 0.07 ± 0.03 g-COD-cell/g-CODsubstrate, suggesting that oxygen diffusion from the cathode possibly supported the microbial growth. In a comparative test, the biomass yield under aerobic environment was 0.46 ± 0.07 g-COD-cell/g-COD-substrate, which was about 3 times higher than the total biomass value in the MFC operation.

• 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.

• KSBB Journal
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• 제10권4호
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• pp.370-373
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• 1995

S.cerevisiae에 의한 에딴올 발효에셔 생성되는 부산물 인 acetic acid, acetaldehyde, glycerol, lactic acid, formic acid가 세포성장과 에탄올 생성에 미치는 영향을 고찰하였다. Acetic acid와 acetaldehyde 를 발효액 내에 투입하였을 때, 세포생장은 저해되 었으나, 에탄올 생성은 증가되었다. 한편, glycerol 과 lactic acid는 세포성장과 에탄올 생산에 거의 영 향이 없었다. Acetic acid와 acetaldehyde는 비성장 속도를 줄임과 동시에 정체기를 늘염으로써 세포성장을 저해하였다. 에단올 수율은 첨가된 acetic acid 와 acetaldehyde 농도에 비례하여 증가하였고, acetic acid $3g/\ell$, acetaldehyde $2g/\ell$ 일 때, 최대가 되었다.

• KSBB Journal
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• 제4권3호
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• pp.271-275
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• 1989

본 논문에서는 Thalictrum rugosum 식물세포의 회분식 배양에 있어서 동역학적 특성들을 연구하였다. 본 실험에서 alkaloid의 생성은 일반적인 2차대사 산물의 생성 특성과 달리 세포성장에 비례함이 확인되었다. 세포 성장기의 비증식속도는 $0.20~0.25\;day\;^{-1}이었으며 FW / DCW 비가 배양상태를 나타내는 중요한 인자임을 알수 있었다. Cell yield는 0.36g cells/g sugar이었으며 berberine은 139mg/L까지 생성되었고 그중 120mg/L는 세포내에 존재하였다. 이를 specific content로 계산하면 dry cell weight의 1.10%가 된다. 세포 성장기에서 비증식속도와 당농도간의 관계는 Monod kinetics로 잘 기술될 수 있었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권5호
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• pp.350-354
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• 2000

The growth promotion of a Taxus brevifolia cell suspension culture was investigated using conditioning factors. The conditioning factors produced and secreted from cultured cells usually stimulate cell division and the production of secondary metabolites. Therefore, the effective incubation time for the optimal secretion of conditioning factors was firstly determined for the promotion of cell growth. Conditioned media obtained by cultivating for 2 and 5 days showed the promotion of initial cell growth during the early cell growth period. However, the positive effect of the conditioning factors on the initial cell growth did not continue because of the depletion of the medium nutrients. Accordingly, the addition of a carbon source to the conditioned medium prolonged the positive effect on the cell growth. The addition of sucrose to the conditioned medium resulted in the maximum cell density being reached 4 days earlier compared to the control group and an increased substrate yield.

• 한국미생물·생명공학회지
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• 제28권5호
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• pp.298-302
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• 2000

Fermentation parameters were estimated by use of a vent gas analyzer coupled to a computer data acquisition system in cultivation of Phellinus linteus WI-001, pro-ducer of polysaccharides known to have potent anticancer activities. Oxygen uptake rate(OUR), a critical indicator of the cells activities, was calculated by applying oxygen mass balance. In addition, by dividing the oxygen uptake rate hy the total oxygen consumed, on-line estimation of the cells specific growth rate was successfully done. It was also possible to estimate cell concentration directly bt use of oxygen-cell yield($Y_{x/o}$ ) which was obtained based on a correlation between cell growth and total oxygen consumed.

• KSBB Journal
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• 제4권1호
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• pp.34-39
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• 1989

본 논문은 동물 세포의 대량 배양을 위해 연속 공법 방식인 Perfusion Continuous System을 도입해 의약적으로 중요한 EPO의 생산을 위한 생물 공학적인 자료들을 제고하고 있다. 이 System은 세포 증식 속도를 배지의 Perfusion 속도로 변화시킴으로써 조절시킬 수 있는 산소 소비속도와 밀접한 상관관계가 있음을 입증하며 이는 세포수의 직접 측정에 따른 오차 및 방법상의 문제를 정학히 측정할 수 있는 간접 변수, 즉 산소소비속도를 이용함으로써 제거할 수 있다. 특히 이 산소소비속도와 세포 성장 관계로 model로써 세포 증식을 예측함과 동시에 동물 세포 대량 배양을 위한 scale-up의 중요한 기초자료가 될 것이다. 지금까지 발표되지 않았던 동물 세포의 glucose에 대한 True growth yield와 maintenance coefficient값들의 측정은 동물 세포 성자관 유용 물질 생산을 위한 중요한 수율적 자료가 된다.한편 이 결과는 지금까지 미생물이나 광합성에서만 적용되었던 yield model이 Eukaryotes에서도 응용될 수 있음을 증명하고 있다. 이와 같이 perfusion system이 많은 장점을 갖고 있지만, 세포 성장에 따른 동력학적인 연구의 수행이 좀 더 요구되는 실정이며, 특히 Perfusion system을 설명할 수 있는 이론 및 cytostatic moel의 정립이 선행되어야 할 것이다.

• Journal of Microbiology and Biotechnology
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• 제11권6호
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• pp.1055-1060
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• 2001

Experimental data for the on-line estimation of cell concentration and growth rate are presented. For this purpose, we utilized the on-line calculation of the oxygen uptake rate (OUR), which was derived from a liquid phase dynamic mass balance for the oxygen during the active growth phase in cyclosporin A (CyA) fermentation. The cell yield coefficient, based on the oxygen $(Y_{x/o})$for both suspended and immobilized cells of Tolypocladium inflatum, was estimated as $1.9 gDCW/gO_2$ from a very good linear correlation between the cell mass produced and the total oxygen consumed. The calculated yield showed a good agreement with the value of $(Y_{x/o})$ generated from the correlation between the cell growth rate and the oxygen uptake rate. In addition, further experimental data are given, which were also applied to determine the specific oxygen uptake rate of T. inflatum cells during the exponential phase of CyA fermentation. A theoretical basis for the analysis of these fermentation parameters is also provided.