• Biotechnology and Bioprocess Engineering:BBE
• /
• 제7권2호
• /
• pp.117-120
• /
• 2002

The effect of cell density on cell growth was investigated in a suspension batch culture of hybridoma cells. The specific growth rate was found to increase with increasing initial cell density and then to decrease with further increases in initial cell density. In order to quantitatively describe the dependence of specific growth rate on cell density, a kinetic model is proposed, which satisfactorily represents the experimental data.

• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
• /
• pp.1098-1101
• /
• 1993

The purpose of this work is to build a fuzzy model of a batch culture for a process control. The process is highly nonlinear system with large delay. This paper presents two methods of modeling the process behavior. One is a method of recognizing them by fuzzy rules that are contracted by the pattern analysis in consideration of skilled operators' way. The other is a method of predicting them by approximate linear models and fuzzy rules by statistic analysis.

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

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제9권3호
• /
• pp.184-190
• /
• 2004

The influences of impeller types on morphology and protein expression were investigated in a submerged culture of Aspergillus oryzae. The impeller types strongly affected mycelial morphology and protein production in batch and fed-batch fermentations. Cells that were cultured by propeller agitation grew in the form of a pellet, whereas cells that were cultured by turbine agitation grew in a freely dispersed-hyphal manner and in a clumped form. Pellet-grown cells showed high levels of protein production for both the intracellularly heterologous protein (${\beta}$-glucuronidase) and the extracellularly homologous protein (${\alpha}$-amylase). The feeding mode of the carbon source also influenced the morphological distribution and protein expression in fed-batch fermentation of A. oryzae. Pulsed-feeding mainly showed high protein expression and homogeneous distribution of pellet whereas continuous feeding resulted in less protein expression and heterogeneous distribution with pellet and dispersed-hyphae. The pellet growth with propeller agitation paralleling with the pulsed-feeding of carbon source showed a high level of protein production in the submerged fed-batch fermentation of recombinant A. oryzae.

• 생명과학회지
• /
• 제17권11호
• /
• pp.1582-1586
• /
• 2007

균주 JH232가 생성한 bacterial cellulose (BC)는 이온교환 막 생산을 위한 환경친화적 재료로서 잠재능이 있다는 것이 전 연구(J. of Chem. Technol. Biotechnol. 2004, 79, 79-84)를 통해 보고되었다. 본 연구를 통해 JH232를 동정하였으며 BC 생성 특성을 조사하였다. 16S rRNA 유전자의 비교분석을 통해 JH232는 Gluconacetobacter sp.인 것을 밝혀냈다. 플라스크실험 결과 이 균주는 초기 pH 5.5로 조절된 CSL 배지에서 온도가 $30^{\circ}C$인 조건하에 배양하였을 때 BC 생성량이 최대를 나타내었다. 발효조 실험을 통해서 회분식 배양보다 유가배양에 의해 JH232의 BC 생성량이 1.56배 더 높게 나타났다.

• Journal of Microbiology and Biotechnology
• /
• 제12권2호
• /
• pp.273-278
• /
• 2002

Two-step fed-batch fermentations were carried out to overproduce Bacillus licheniformis maltogenic amylase (BLMA) in recombinant Escherichia coli. The first step was to increase the cell mass by controlling the feeding of a glucose solution, while the second step was designed to improve the amylase expression efficiency by supplementing organic nitrogen sources. The linear gradient feeding method was successfully adopted to maintain the glucose concentration below 0.2 g/l during the fed-batch mode, as effectively minimizing acetic acid formation. When the dissolved oxygen (DO) level became limiting, an accumulation of acetic acid and drastic decrease in specific BLMA productivity were observed. Glucose and organic nitrogen sources consisting of yeast extract and casein hydrolysate were simultaneously supplied in the pH-stat mode to further increase the specific BLMA expression efficiency. An organic nitrogen source consisting of 200 g/1 yeast extract and 100 g/1 casein hydrolysate was found to be the best among the various combinations tested. The feeding of an organic nitrogen source in the second-step fed-batch period was highly beneficial in enhancing the BLMA production. The optimized two-step fed-batch culture resulted in 78 g/l maximum dry cell mass and 443 U/ml maximum BLMA activity, corresponding to 1.5-fold increase in the dry cell mass and 3.7-fold enhancement in BLMA production, compared with the simple fed-batch fermentation.

• 한국식품영양과학회지
• /
• 제25권4호
• /
• pp.708-714
• /
• 1996

호기성의 Rhizopus japonicus와 혐기성 Zymomonas mobilis로 구성된 혼합고정화 배양계(R-Z계)를 제조하고, 생전분으로부터 에탄올 생산에 응용하였다. R. japonicus를 고정화배양하므로서 액체배양에서 보다 2배 높은 glucose량을 얻었다. R-Z계의 에탄올 생산량은 1.67g/L(Yp/s, 0.094)이 었지만, 배양 24시간째부터 산소공급을 억제한 R-Z 24계에서는 6.54g/L(Yp/s, 0.38)의 에탄올을 얻어 대조구의 약 4배를 향상시켰다. 회분배양에서는 5%의 기질 농도가 적당하였으며, 생산된 에탄올은 15.02g/L(Yp/s, 0.36)이었다. 2% 기질을 5회 첨가한 유가배양에서는 2%기질의 회분배양과 동등한 수율인 0.38을 얻었다.

• Journal of Microbiology and Biotechnology
• /
• 제9권5호
• /
• pp.548-553
• /
• 1999

A production of $\beta-Carotene$was attempted in a fed-batch culture of Blakeslea trispora by controlling both foam and dissolved oxygen in the presence of surfactant, Span 20. Results obtained from the shake flask cultures indicated that a high concentration of dissolved oxygen was needed for both cell growth and $\beta-Carotene$ synthesis, and the optimal concentration of glucose was found to be in the range of 50-100 g/l. In order to maintain the dissolved oxygen concentration level at higher than 50% of air saturation, pure oxygen was automatically sparged into the medium with air. Foam was controlled by bypassing air from the submerged aeration to the headspace in response to the foam that was caused by Span 20. High agitation speed was found to be detrimental to the cell growth due to shear damage, even though it provided sufficient dissolved oxygen. On the other hand, a low aeration speed caused stagnant regions in the fermentor because of improper mixing. Thus, for the fed-batch operation, agitation speed was increased gradually from 300 to 700 rpm to prevent cell damage at the initial stage of fermentation and to give efficient mixing for a viscous culture broth as the culture proceeded. By controlling dissolved oxygen and foam, a high concentration of $\beta-Carotene$otene (1,190 mg/l) was obtained in 6 days of the fed-batch culture of B. trispora with 2.5% of the dry cell weight, which was approximately 5 times higher than that of the batch cultures.

• 한국미생물·생명공학회지
• /
• 제46권4호
• /
• pp.390-394
• /
• 2018

Endoxylanase와 endoglucanase 유전자가 ADH1 프로모터 하류에 따로따로 삽입된 pAGX3 플라스미드를 함유한 Saccharomyces cerevisiae에서 endoxylanase와 endoglucanase 유전자는 성공적으로 발현되었으며, YPD 배지에서의 회분배양 결과, endoxylanase는 7.91 units/ml, endoglucanase는 0.43 units/ml에 달하는 총활성을 보였다. Yeast extract와 포도당을 간헐적으로 공급하는 유가배양에서 endoxylanase와 endoglucanase의 총활성은 24.9 units/ml과 0.84 units/ml을 각각 보였으며, 이는 회분배양에서 발현된 각각 활성의 3.1배와 2배에 해당되었다. 또한, 대부분의 endoxylanase와 endoglucanase 활성은 세포밖 배지에서 측정되어, 향후 이 재조합 효모는 섬유소(cellulose)와 xylan 혼합물의 동시당화 바이오공정 개발에 활용될 가능성이 높다 하겠다.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2000년도 춘계학술발표대회
• /
• pp.295-298
• /
• 2000

In order to maximize the RNA accumulation and biomass production in Saccharomyces cerevisiae MTY62, a high-content RNA yeast strain, fed-bach cultures were performed with optimized industrial medium including molasses and corn steep liquor. Among the feeding modes examined, the constant feeding mode resulted in the cell concentration of 35.7 g-DCW/L and the RNA concentration of 5434 ${\mu}g-RNA/mL$, which were about 2-fold increased levels, compared to the results of bach culture. However, the RNA content (153 mg-RNA/g-DCW) in the fed-batch cultures was lower than that in the batch culture (171 mg-RNA/g-DCW).