• KSBB Journal
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• 제13권4호
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• pp.456-460
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• 1998

Fed-batch fermentations were carried out in order to improve the efficiency of hirudin production by recombinant Saccharomyces cerevisiae. A fed-batch fermentation done with the optimized semi-synthetic medium resulted in a maximum hirudin concentration of 342mg/$\ell$ by keeping a galactose concentrations between 10 and 30g/$\ell$ which corresponded to a 11.4-fold increase in hirudin concentration compared with the simple bach fermentation done with the same medium. Comparison of the chromatographic pattern of proteins in the growth medium clearly showed that the use of the semi-synthetic medium is more advantageous for separation of hirudin than the case o fusing the complex medium. Continuous cell recycle fermentation done at dilution rate of 0.1h-1 and an inlet galactose concentration of 100g/$\ell$ yielded a maximum hirudin productivity of 19.1mg hirudin/$\ell$$.$h.

• 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%.

• KSBB Journal
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• 제13권4호
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• pp.411-417
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• 1998

The possibility of application of membrane type immobilized adsorbent to the fed-batch or perfusion culture system with anchorage-independent cells as well as batch system was investigated. The improvement in cell density and cell viability due to the combination of immobilized adsorbent with each culture system was evaluated for the investigation, and the optimum culture system employing immobilized adsorbent system was suggested based on the results. It was observed that the system with immobilized adsorbent showed better cell growth and cell viability than that without immobilized adsorbent in every operation system of batch, fed-batch, and perfusion. In case of batch system, 200% improvement of maximum cell density was observed in the system where ammonium chloride was added on purpose. And 50% improvement of maximum cell density was observed in the fed-batch system where ammonium ion accumulates significantly, while small increase in maximum cell density was observed in the perfusion system where dilution of waste byproducts exists. Especially, the fed-batch system showed the most significant improvement on cell growth because both compensation of nutrient and removal of ammonium ion occurred simultaneously in the system. Therefore a combined system of immobilized adsorbent and fed-batch operation could be suggested as an optimum system with in situ removal of ammonium ion.

• Journal of Microbiology and Biotechnology
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• 제5권4호
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• pp.229-233
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• 1995

Acremonium chrysogenum was immobilized in ionotropic gel beads to develop semi-continuous production of cephalosporin C (CPC). Barium alginate beads were more stable than calcium alginate or strontium alginate beads in chemically defined media. The gel stability of Ba-alginate was further increased by cross-linking with polyethyleneimine (PEI). The presence of carboxymethyl cellulose inside Ba-alginate beads did not reduce mass transfer resistance. Ba-alginate microbeads that had little diffusion limitation increased CPC production rate 1.6 fold higher than that of normal beads. CPC fermentation with immobilized cells in Ba-alginate microbeads was performed continuously for 40 days by way of repeated fed-batch operations. Mathematical modeling was developed to describe the repeated fed-batch fermentation system. Results of the computer simulation agreed well with the experimental data, which made it possible to predict an optimal feeding rate that could maximize total CPC productions.

• KSBB Journal
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• 제15권5호
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• pp.489-496
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• 2000

고농도 유전자 재조합 대장균을 이용하여 pyruvate dehy-drogenase complex-E2 특이성 인간 모노클론 항체의 Fab 부분을 효율적으로 생산하기 위해 회분식, 이단 연속식, 반 유 가식, two-stage cyclic fed-batch 동 여러 가지 배양 방법이 조사되었다. 먼저 플라스미드 안정성 문제를 극복하기 위해 growth stage와 production stage를 분리하는 two-phase 회분식 배양과 이단 연속식 시스템을 시도하였다 그 결과 two-phase 회분식 배양보다는 이단 연속식 배양에서의 세포농도와 항체 생산성이 우수하였다 또한 이단 연속식 배양에서의 세포 성 장과 항처l 생산성은 용존산소를 제어한 경우가 그렇지 않은 경우보다 월등하게 높았다. 그리고 plasmid 안정성에 있어서 는 실험기간 내에 거의 100%를 유지하여 높은 안정도를 보 여주었다. 유가식 공정에 적합한 공급 배지로 변형된 M9 배 지가 최적배지로 선정되었고 이 배지 중 최적의 CjN 비율을 조사한 결파 2:3으로 결정되었다. 반 유가식 시스템에서 constant feeding 전략을 사용할 경우 최적 공급속도는 $0.6g/\ell/hr$이었다. 또한 pulse에 의해 공급배지를 공급할 경우에는 총 공급 량이 같을 경우 소량으로 자주 공급해 주는 것이 공급배지를 한꺼번에 많은 양을 공급해주는 것 보다 바람직하였다. 여러 가지 feeding 전략을 조사해 본 결과 linear feeding 방법이 가장 효과적이었다. 하지만 linear feeding 방법마저도 고농도 세포배양에 한계가 있었기 때문에 pH-stat 방법을 이용한 two-stage cyclic fed-batch 시스템을 시도하여 $54 g/\ell$의 세포 를 얻을 수 있었다. 따라서 이 방법이 일단 생산성 향상을 위한 세포의 고농도 배양에는 조사한 여러 배양 시스템 중에 가장 효율적인 시스템임올 알 수 있었다 하지만 이 시스템 에서 포도당을 낮은 level로 유지할 수 있었으나, 초산의 과도한 축적으로 항체 생산성의 향상은 예상에 비해 크지 않았다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.184-187
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• 2002

Lovastatin is a cholesterol-lowering agent, which plays a role of an inhibitor of 3-hydroxy-3- methylglutaryl coenzyme A reductase (HMG-CoA). When thiamine was supplemented in 3L batch fermentation, the production of lovastatin was improved. At the same time, the levels of pyruvic acid and NAD(P)H were estimated in the course of the fermentation of A. terreus. For the high level production of lovastatin, semi fed-batch fermentation was performed. And the thiamine level was maintained to a concentration of 20 mg/L and glucose was supplied. The final dry cell weight was lowered by 30 % and final lovastatin concentration was increased by 33 %. Final lovastatin concentration of 3.3 g/L was achieved in 8 days.

• 한국농공학회논문집
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• 제53권1호
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• pp.63-69
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• 2011

The green algae Scenedesmus acuminatus was cultured in different media: animal wastewater and an artificial culture medium in order to evaluate potential use for tertiary treatment. The experiments were conducted with air flowrate 1~2 L/min at $28{\sim}30^{\circ}C$. The nitrogen and phosphorus showed very similar removal efficiencies (68~77 % and 69~80 % for nitrogen and phosphorus respectively). The optimal fed period was estimated as three days in the semi-continuous experiment. The effects of $CO_2$ (4.5 %) injection on nutrient uptake from animal wastewater (biological treatment effluent) were compared to an air injection under the same conditions of light and photoperiod. The uptake rates of nutrient with air injection were observed 0.009 gN/gChl-a/day, 0.028 gN/gChl-a/day and T-P 0.003 gP/gChl-a/day for nitrate, total nitrogen and phosphorus respectively. The rates were enhanced by addition of $CO_2$ to 0.026 gN/gChl-a/day, 0.076 gN/gChl-a/day and T-P 0.018 gP/gChl-a/day. This study establishes that $CO_2$ addition during nutrient deprivation of microalgal cells may accelerate tertiary wastewater treatment.

• 한국미생물·생명공학회지
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• 제26권1호
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• pp.61-67
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• 1998

재조합 인간상피세포 성장인자(rhEGF)가 E. coli BL21(pYHB101) 균주를 사용하여 발현되었다. 10g/L glucose를 첨가한 변형된 MBL 배지를 사용하여 10 $\mu\textrm{m}$ IPTG/lactose로 2시간 동안 유도배양한 후 27$^{\circ}C$에서 48시간 동안 배양하였을 때 44.5 mg/L의 rhEGF가 발현되었다. 상기의 결과는 E. coli BL2l(pYHB101)를 사용하여 rhEGF를 발현시 lactose를 IPTG와 동일한 유도 물질로 사용 가능하다는 것을 시사하는 것이다. 회분식 배양에서 glucose를 10 g/L 첨가한 변형된 MBL 배지에 유도물질로 10 $\mu\textrm{m}$ lactose를 사용하였으며 28시간 동안 배양하였을 때 최대 45 mg/L의 rhEGF가 발현되었다. 유가식 배양에서 정지기에 0.5%(w/v) lactose와 0.25%(w/v) yeast extract를 첨가하였을 때 160mg/L의 rhEGF가 발현되었으며 94.3%가 분비되었다. 이에 비하여 유도기에 lactose를 첨가한 경우는 120 mg/L의 rhEGF가 발현되었으며 cytoplasm으로 발현된 불용성 봉입체의 비율은 20.9%에 달하였다. 이것은 lactose의 첨가시기가 E. coli BL2l(pYHB101)로부터 soluble rhEGF의 생성에 중요하다는 것을 확인한 결과이다.

• 한국미생물·생명공학회지
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• 제20권6호
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• pp.663-667
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• 1992

산업적으로 산도 17.0 이상의 고산도 시초를 생산하기 위하여 반연속식인 1st stage와 유가식인 2nd stage로 구성된 two stage 초산 발효를 온도 $30^{\circ}C$, 교반속도 600rpm, 통기량 0.1vvm에서 실시하였다. 1st stage에서 초기 에탄올 농도를 $50.0g/{\ell}$, 잔류 에탄올 농도를 $5.0g/{\ell}$로 정하여 반연속적으로 초산발효를 하고, 2nd stage에서 발효시간의 경과에 따라 에탄올을 유가식으로 첨가하여 초산발효액내의 에탄올 농도를 $5.0g/{\ell}$에서 $10.0g/{\ell}$로 유지했을 때 산도가 17.6인 고산도 식초를 생산 할 수 있었으며, 또한 이때의 최대 초산 생산성은 $3.3g/{\ell}{\cdot}hr$였다.

• 환경위생공학
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• 제4권1호
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• pp.43-52
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• 1989

A synthetic wastewater composed of powdered baby food and inorganic nutrients was treated by five 3.6L anaerobic reactors in order to test the relationship between solids retention time (SRT) and media surface ratio, and the removal efficiencies of organic substrate. Of the five reactors, four were semi-continuously fed stirred-tank reactors and one continuously-stirred batch reactor. The influent was 7430mg/L in COD, 7120 mg/L $BOD_L$ and 6350mg/L in $BOD_5$, respectively. Operating temperature was $35{\pm}1^{\circ}C$ and pH in the range 6.9 to 7.2. In this experimental study it was found that a linear relationship existed, within the experiment range, between SRT and media surface ratio, and that SRT and removal efficiency increased with increasing media surface ratio. The substrate removal efficiencies were 82.7 to $88.2\%$ in COD, 82.9 to $88.4\%$ in $BOD_L$ and 83.3 to $88.7\%$ in $BOD_5$, respectively.