• KSBB Journal
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• 제6권1호
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• pp.15-25
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• 1991

The optimal glucose concentration for the high-density culture of recombinant yeasts was obtained using dynamic simulation. An adaptive and predictive algoritilm complimented by the rule base was proposed for the control of the fed-batch fermentation process. The measurement of process variables has relatively long sampling period and relatively long time delay characteristics. As one of the solution on these problems, prediction techniques and rule bases were added to a classical recursive identification and control algorithm. Rule bases were used in the determination of control input considering the difference between the predicted value and the measured value. A mathelnatical model was used in the estimation and interpretation of the changes of state variables and parameters. Better performances were obtained by employing the control algorithm proposed in the present study compared to the conventional adaptive control method.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권5호
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• pp.303-305
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• 2003

Scale-up of hirudin production from Saccharomyces cerevisiae from bench-scale to pilot-scale was carried out based on constant volumetric oxygen transfer coefficient (K$\sub$L/a). Fed-batch mode of cultivation using step-wise feeding strategy of galactose was employed for the production of hirudin in a 30-L and a 300-L pilot-scale fermentor. The final hirudin concentrations were achieved 390 mg/L and 286.1 mg/L, and the volumetric productivities were 80.4% and 90.7% with the 30-L and 300-L fermentors, respectively, compared to the productivity of the 5-L bench-scale fermentor.

• Journal of Microbiology and Biotechnology
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• 제21권10호
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• pp.1053-1056
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• 2011

Optimal conditions for a high cell density fermentation were investigated in a recombinant Escherichia coli producing salmosin, a platelet aggregation inhibitor. The optimized carbon and nitrogen sources were glycerol 10 g/l, yeast extract 30 g/l, and bacto-tryptone 10 g/l, yielding the dry cell weight (DCW) of 10.61 g/l in a 500 ml flask culture. The late-stage induction with 1% L-arabinose in a 5 l jar fermentor showed the highest DCW of 65.70 g/l after 27 h of the fed-batch fermentation. Around 2,200 mg/l of the protein was expressed as an inclusion body that was then refolded to obtain the active salmosin of 96 mg/l. We also confirmed the inhibitory activity against platelet aggregation of the active salmosin from the high cell density fermentation.

• 한국미생물·생명공학회지
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• 제32권2호
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• pp.149-153
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• 2004

븐 연구에서는 E. coli MT201을 이용한 L-threonine 발효공정을 확립하였다. 회분식 배양에서 L-threonine생산이 균체 증식과 더불어 증가하는 증식과 연관된 형태의 생산 곡선을 보여주었다. L-Threonine 생산에 대한 조건을 확립하기 위한 유가식 배양에서 첨가배지내 최적 효모추출물과 포도당의 농도는 각각 60 g/$\ell$와 600 g/$\ell$이였으며, 약 87 g/$\ell$의 L-threonine이 생산되었다. 유가식 배양에서도 L-threonine 생산은 회분식 배양과 마찬가지로 균체량의 증가와 더불어 L-threonine 생산이 증가하는 증식과 연관된 형태를 보여주었다. 이러한 결과를 바탕으로 적절한 균체량의 증가와 L-threonine 생산성 향상을 위하여 L-methionine과 인산염이 추가로 공급된 첨가배지를 이용한 고농도 배양 조건이 확립되었다. 한편 고농도 배양에 따른 용존산소의 결핍을 해결하기 위하여 산소가 포함된 혼합공기를 사용하였다. 최적화된 유가식 배양 결과 균체 증식도 원활하게 증가하였으며, L-threonine의 생산도 약 98 g/$\ell$로 향상되었다. 이때 L-threonine의 생산성은 약 3.85 g/$\ell$/h이었다.

• 한국식품과학회지
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• 제15권2호
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• pp.202-204
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• 1983

이산화탄소 측정기 및 제어기를 사용하여 글루탐산 발효공정의 자동화 방법을 개발하였다. 이는 발효배기가스 중의 이산화탄소와 균체의 성장 간에 직선관계가 있고 따라서 적절한 균체농도에서 페니실린 투여를 자동화할 수 있었다. 페니실린 투여 후 균체성장 및 글루탐산 생성의 고농도당에 대한 저해작용을 감소시켜 주기 위한 방법으로서 회분식 추가당 첨가공정을 자동화할 수 있었으며, 그 결과로서 회분식 발효에 비하여 생산성과 수율이 향상되었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권4호
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• pp.296-303
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• 2005

A strain named as HJ35 was isolated from the skin of sixty-five men and fourteen women for acne therapy, in order to find an effective antimicrobial agent against Propionibacterium acnes. Isolate HJ35 was identified as Enterococcus faecium based on 16 rDNA sequence and produced enterocin HJ35 having antimicrobial activities against most lactic acid bacteria, En­terococcus spp., Staphylococcus aureus, S. epidermidis, Clostridium perfringens, some bacilli, Mi­crococcus flavus, Listeria monocytogenes, L. ivanovii, Escherichia coli, Pseudomonas fluorescens and Propionibacterium acnes, in the modified well diffusion method. Especially, enterocin HJ35 showed a bactericidal activity against Propionibacterium acnes P1. The antimicrobial activity of enterocin HJ35 was disappeared completely with the use of protease XIV. But enterocin HJ35 activity is very stable at high temperature (up to $100^{\circ}C$ for 30 min), in wide range of pH (3.0${\~}$9.0), and by treatment with organic solvents. The apparent molecular mass of enterocin HJ35 was estimated to be approximately 4${\~}$4.5 kDa on detection of its bactericidal activity after SDS-PAGE. In batch fermentation of E. faecium HJ35, enterocin HJ35 was produced at the mid­log growth phase, and its maximum production was obtained up to 2,300 AU/mL at the late stationary phase. By employing fed-batch fermentation, the enhanced production of enterocin HJ35 was achieved up to 12,800 AU/mL by feeding with 10 g/L glucose or 6 g/L lactate.

• Journal of Microbiology and Biotechnology
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• 제34권3호
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• pp.710-724
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• 2024

Flavobacterium can synthesize xanthophyll, particularly the pigment zeaxanthin, which has significant economic value in nutrition and pharmaceuticals. Recently, the use of carotenoid biosynthesis by bacteria and yeast fermentation technology has shown to be very efficient and offers significant advantages in large-scale production, cost-effectiveness, and safety. In the present study, JSWR-1 strain capable of producing xanthophyll pigment was isolated from a freshwater reservoir in Wanju-gun, Republic of Korea. Based on the morphological, physiological, and molecular characteristics, JSWR-1 classified as belonging to the Flavobacterium species. The bacterium is strictly aerobic, Gram-negative, rod-shaped, and psychrophilic. The completed genome sequence of the strain Flavobacterium sp. JSWR-1 is predicted to be a single circular 3,425,829-bp chromosome with a G+C content of 35.2% and 2,941 protein-coding genes. The optimization of carotenoid production was achieved by small-scale cultivation, resulting in zeaxanthin being identified as the predominant carotenoid pigment. The enhancement of zeaxanthin biosynthesis by applying different light-irradiation, variations in pH and temperature, and adding carbon and nitrogen supplies to the growth medium. A significant increase in intracellular zeaxanthin concentrations was also recorded during fed-batch fermentation achieving a maximum of 16.69 ± 0.71 mg/l, corresponding to a product yield of 4.05 ± 0.15 mg zeaxanthin per gram cell dry weight. Batch and fed-batch culture extracts exhibit significant antioxidant activity. The results demonstrated that the JSWR-1 strain can potentially serve as a source for zeaxanthin biosynthesis.

• 한국미생물·생명공학회지
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• 제17권3호
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• pp.263-268
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• 1989

유전자의 재조합 균주의 생산성을 향상시키기 위한 발효시스템 개발을 목적으로 regulated promoter 인 SUC2 gene 갖는 유전자 재조합 S. cerebisiae를 모델로하여 유전자 산물인 Invertase 발현에 미치는 글루코오스 농도의 영향, 발효 중 플라스미드의 불안정성, 생육특성 및 continuous fed batch system을 연구하였다. 유전자 재조합 균주는 biphasic growth 현상을 보였으며 글루코오스 농도가 0.9g/$\ell$에서 2.2g/L로 증가함에 따라 비증식 속도는 0.224 h$^{-1}$에서 0.226 h$^{-1}$로 증가했으며 숙주효모보다 낮은 값을 나타내었다. 유전자 재조합 균주의 invertase 생산은 발효조내의 글루코오스 농도에 크게 영향을 받아 글루코오스 농도가 0.25~0.4g/L로 감소될 때 invertase 생산이 시작되었으며 회분발효중 플라스미드의 분리는 글루코오스 자화기간 동안에 빈번히 일어났으나 에탄을 자화기간에는 완만해지는 경향을 보였다. 또한 통기를 해주지 않고 배지의 용존산소만으로 배양시킨 결과 통기를 한 경우에 비하여 invertase의 비활성과 총활성이 각각 1.5 및 1.3 배 증가되었다. 균체의 증식단계와 유전자의 발현단계로 구분하여 발효시키기 위하여 영양분을 함유한 글루코오스 용액을 48m1/h(0.096g 글루코오스/48L의 유량으로 12시간 연속적으로 공급하여 fed batch 배양한 결과 invertase의 비활성과 총활성이 비통기적 회분배양 보다 각각 1.74, 2.74배 증가되었다.

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

• Journal of Microbiology and Biotechnology
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• 제5권4호
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• pp.224-228
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• 1995

Fed-batch fermentations were conducted to produce human lipocortin-I (LC1), a potential anti-inflammatory agent, from recombinant Sacchromyces cerevisiae carrying a galactose-inducible expression system. The cell growth, expression level of LC1, and the plasmid stability were investigated under various LC1 induction modes performed by three different galactose feeding strategies. Galactoe was fed to induce the expression of LCl from the beginning (initial induction) of culture or when the cell concentration reached 120 OD (mid-phase induction) or 300 OD (late induction). Among the three galactose-induction modes tested, the initial induction mode yielded the best result with respect to a final expression level of LC1. Fedbatch fermentation with initial induction mode produced LC1 at a conentration of 220 mg/l, which corresponded to 1.38- and 1.53-fold increases over those produced by mid-phase and late induction modes.