• 한국미생물·생명공학회지
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• 제23권4호
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• pp.479-484
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• 1995

The effect of initial cell concentration on the characteristics of ethanol fermentation was investigated in the batch fermentation of Saccharomyces cerevisiae ATCC 24858. The characteristics were investigated in the range of 60 to 230 g/l of the initial sugar concentrations and 0.5 to 85 g/l of the initial cell concentrations. When the initial cell concentrations were 27 g/l for 60 g/l of the initial sugar and 85 g/l for 230 g/l, the fermentation time required for the complete consumption of the initial sugar was one hour, respectively. The ethanol productivity increased with the initial cell concentration so that, in the case of 100 g/l of initial sugar, the productivity rose up to 55 g/l/hr at 55 g/l of the initial cell concentration. The specific growth rate decreased according to the increase in the initial biomass concentration and finally became zero at around 25 g/l of the cell concentration regardless of the initial sugar concentration. The specific ethanol production rate was constant as 1.02 g/l/hr up to 150 g/l of the initial sugar. However, the rates decreased sharply with the augmentation of concentration of the initial sugar above 160 g/l. The overall ethanol yield represented a constant value, 0.475 g/g irrespective of the initial cell and sugar concentrations. The overall biomass yietd showed a trend to diminish in values with the biomass and ultimately to reach zero more than 25 g/l of the initial cell concentration.

• 한국미생물·생명공학회지
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• 제23권6호
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• pp.717-722
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• 1995

Using a flocculating Saccharomyes cerevisiae CA-1, an air-lift reactor equipped with a modified settler was used for ethanol fermentation. The effects of conditions such as aeration rate, initial glucose concentration, and dilution rate were studied using the air-lift reactor. In batch fermentation, optimum aeration rate was 0.5 vvm. In continuous fermentation, aeration rate and initial pH were fixed 0.5 vvm and 4.5, substrate concentration and dillution rate were changed 10-15% and 0.1-1.3. The maximum ethanol productivity was shown to be 20.4 g/l$\cdot $h in 10% glucose and 0.7 h$^{-1}$ dilution rate., and optimum operation condition considering the ethanol productivity and glucose utilization ratio was 0.5 h$^{-1}$ dilution rate in 10% glucose concentration.

• 한국식품영양과학회지
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• 제32권6호
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• pp.812-817
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• 2003

딸기식초 제조를 위해 1차 단계로 Saccharomyce kluyeri DJ97을 이용하여 딸기과즙을 14$^{\circ}$Brix로 보당한 후 28$^{\circ}C$에서 50시간동안 발효시켜 딸기 알콜발효액을 얻은 후 사용하였다. 2차 단계에서, 초산발효를 시킨 결과 산도는 초기산도가 1.48%, 교반속도가 195.76 rpm, 발효시간이 7.34 day일 때 가장 높은 4.60%를 나타내었다. 색차계 a값은 초기산도가 1.78%, 교반속도가 117.63 rpm. 발효시간이 7.35 day일 때 가장 높은 11.82를 나타내었다. 딸기식초 제조를 위해서는 Acetobacter sp. PA97를 이용하여 초기산도 1.5% 및 교반속도 196 rpm에서 176시간 발효함으로서 산도 4% 이상의 식초를 얻었다.

• KSBB Journal
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• 제8권2호
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• pp.178-184
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• 1993

Extractive fermentations with the extract of Jerusalem artichoke in an aqueous-two-phase-system of polyethyleneglycol(PEG) and dextran(Dx) were investigated to obtain the effects of composition of PEG and Dx on both fermentation ,characteristics and partition ratio of alcohol. The specific growth rate of K. Fraglis CBS 1555 increased with a decrease of concentration of PEG and Dx. It augmented along with concentration of initial sugar up to 80g/l but decreased thereafter. The specific production rate of alcohol showed a rising tendency up to 100g/lof initial sugar, whereafter represented a decreasing trend. The partition ratio of alcohol between two phases augmented according to decrease of Dx comic. and increase of PEG cone. regardless of initial sugar concentrations. The ratio, however, decreased with Increment of initial sugar concentration at constant composition of PEG and Dx. The partition coefficient of alcohol had an ascending effect to the increase of PEG cone, but it had little effect on the changes of concentrations of Dx and initial sugar. The present study suggests that the optimum composition of PEG and Dx in the aqueous-two-phase-system by extractive fermentation were around 6.5%(w/v) of PEG and 3%(w/v) of Dx in considerations of emulsion state, sedimentation and separation of two phases, alcohol partition ratio, and specific growth rate.

• KSBB Journal
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• 제9권5호
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• pp.443-449
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• 1994

여러 가지 조성의 PEG 20000jDx로 구성한 수성 이상계를 사용한 에탄올 추출발효실험을 통하여 K. fragilis에 의한 돼지감자 주스의 발효 특성을 초기 당농도 및 생성 알코올 농도의 함수로 규명하여 다음의 결과를 얻었다. 균체의 비증식속도 빛 에탄올 비생성속도는 PEG 및 Dx 농도가 낮을수록 증가하였다. 비증식속도는 조성에 무관하게 초기 당농도 $80g/\ell$에서 최대치를 보였고, 에탄올 비생성속도는 $120g/\ell$최대치를 보였다. 생성 알코올 농도에 의한 저해 영향은 비증식속도에 대하여 지수함수형 을, 에탄올 비생성속도에 대하여 쌍곡선함수형을 나타냈다. Dx 농도가 2.5~5% 범위에셔 PEG 농도 가 낮을수록 에탄올 저해 영향은 감소하였다. 총괄 에탄올 생산성은 초기 당농도가 증가할수록 높았으 며 생산성이 최대치에 도랄하는 소요시간도 당농도가 증가함에 따라 증가하였다. 시간별 에탄올 생산 속도는 초기 당농도 $160g/\ell$ 에서 가장 높은 값을 보 였다. 총괄 에탄올 생산성은 대조실험에 비하여 수 성이상계 추출발효를 통하여 1.2배 이상 증가하였고 초기 당농도가 높을수록 이상계 추출발효가 더욱 유리한 것으로 나타났다.

• 한국식품과학회지
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• 제35권4호
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• pp.642-647
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• 2003

곶감가공 부산물인 감껍질을 효율적으로 이용하기 위하여 2단계로 알콜 및 초산 발효에 의해 감식초를 제조하였다. 감껍질을 이용한 알콜발효에서 알콜함량은 가수량이 12.43 mL/g 일 때, 초기 당함량 $12.41^{\circ}Brix$ 및 발효시간이 48.05 hr의 발효조건에서 최대치(8.22%)를 나타내었다. 산함량은 가수량이 12.18 mL/g 초기 당함량 $13.72^{\circ}Brix$ 및 발효시간이 46.22의 발효시간에서 최소치(0.30%)를 나타내었다. 초산발효에서 총산의 함량은 초기산도가 2.02%, 교반속도가 67.98 rpm 및 발효시간이 6.94 day일 때 최대치(6.40%)를 나타내었고, 갈색도는 초기산도가 1.50%, 교반속도가 150.00 rpm및 발효시간이 6.00 day일 때 가장 낮은 흡광도를 나타내었다. 감껍질을 이용하여 감식초를 제조하기 위해서 1차 알콜 발효조건은 가수량 12 mL/g, 초기 당함량 $12^{\circ}Brix$ 및 발효시간 48 hr로 할 때 감 알콜발효액을 제조할 수 있으며, 2차 초산발효조건은 초기산도 1.8%, 교반속도 70 rpm 및 발효시간 6 day인 것으로 나타났다.

• 한국미생물·생명공학회지
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• 제23권6호
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• pp.723-729
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• 1995

A flocculating sugar tolerant yeast strain was isolated from fermenting Takju. This strain was identified as Saccharomyces cerevisiae CA-1 according to the Lodder's yeast taxonomic studies. The isolated yeast could grow in 50% glucose and in 7% ethanol in the YPD medium. It's optimal growth temperature, initial pH, shaking rate and initial glucose concentration for ethanol fermentation showed 35$\circ$C, 4.5, 150 rpm, 15%, respectively. Ethanol concentration was 63 g/l in 20% glucose after 24 hours, fermentation yield was 0.49 g-ethanol/g-glucose in 10% glucose after 24 hours and ethanol productivity was 3.09 g/l$\cdot $h in 10% glucose after 12 hours in batch fermentation. Repeated batch fermentation was possible for over 50 days and ethanol yield, ethanol productivity and substrate conversion rate were 0.39-0.50 g/g, 1.63-2.08 g/l$\cdot $h and more than 99%, respectively during these periods.

• 동아시아식생활학회지
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• 제8권1호
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• pp.57-65
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• 1998

To utilize deteriorated sweet persimmon effectively, response surface methodology(RSM) was used to determine the optimal vinegar fermentation conditions and monitored by a divided two stage fermentation. The optimum conditions for maximum alcohol content were obtained when the first stage (alcohol fermentation) was carried out with an initial sugar concentration of 18.5$^{\circ}$Brix, agitation rate of 140.8 rpm, fermentation time of 127.6 hr. When sugar concentration was 14$^{\circ}$Brix maximum alcohol content(7.1%) was predicted at fermentation conditions of 160 rpm in agitation rate, 140hr in fermentation time. The optimum conditions for maximum acidity were obtaiend when second stage(vinegar fermentation)was carried out 249.5 rpm in agitation rate, 148.8 hr in fermentation time. Predicted values at the optimum conditions were similar to experimental values.

• 한국미생물·생명공학회지
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• 제23권5호
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• pp.624-631
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• 1995

The fermentation characteristics of Saccharomyces cerevisiae F38-1, a newly isolated thermotolerant yeast strain from a high temperature environment have been studied using a fermentation medium containing 20% glucose, 0.2% yeast extract, 0.2% polypeptone, 0.3% (NH$_{4}$)$_{2}$SO$_{4}$, 0.1% KH$_{2}$PO$_{4}$, and 0.2% MgSO$_{4}$ without shaking at 30$\circ$C to 43$\circ$C for 5 days. The fermentability was over 90% at 30$\circ$C, 88% at 37$\circ$C, 77% at 40$\circ$C and 30% at 43$\circ$C. A similar fermentation result was obtained at pH between 4 and 6 at 30$\circ$C and 40$\circ$C. Aeration stimulated the growth of the strain at the beginning of the fermentation, but it reduced alcohol production at the end of alcohol fermentation. Optimal glucose concentration was determined to be between 18 and 22% at 40$\circ$C as well as 30$\circ$C, but the growth was inhibited at the glucose concentration of over 30%. A fermentability of over 90% was observed at 40$\circ$C in 2 days when the medium was supplemented by 2% yeast extract. A higher inoculum size increased the initial fermentation rate, but not the fermentation. A fermentability of over 90% was achieved in 2 days at 40$\circ$C in a fermentor experiment using an optimized medium containing 20% glucose and 1% yeast extract.

• 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.