• 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.

• KSBB Journal
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• 제6권3호
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• pp.255-261
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• 1991

The effect of concentration of yeast extract and NH4Cl in the mediun of alcohol fermentation of S. cerevisiae ATCC 24858 on the fermentation characteristics, specific growth rate, sugar conversion, alcohol productivity was experimentally investigated. Regardless of initial sugar concentrations, the values of the above three characteristics increased with augument of concentration of yeast extract. However, the increasing tendency ceased above a certain concentration. The concentration of NH4Cl had little effect on the change of the three characteristics. The functional relationships between the concentration of yeast extract and the characteristics were different according to the initial sugar concentrations, but those between the ratio of yeast extract concentration to initial sugar concentration and the characteristics could be expressed as same forms respectively regardless of initial sugar concentrations. Also the values of the three characteristics approached to the maximum values around 0.085 of the ratio, but did not increase any more above 0.1 of the ratio. We have come to conclusion that the optimum ratio of the yeast extract concentration to the initial sugar concentration was about 0.085 and the ratio should not be decided as greater than 0.1 in the medium of alcohol fermentation of S. cerevisiae ATCC 24858.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.313-316
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• 2000

The effects of initial sugar concentration and the various nitrogen sources on the fermentation characteristics of Thraustochytrium aureum were investigated. The sugar conversion ratios decrease with increase in the initial sugar concentration regardless of the kinds of nitrogen sources. The specific growth rate, the biomass yield, and the DHA yield also decreased but approached constant values higher than the concentration of 30g/L. The sugar conversion ratios and the specific growth rate showed the highest values in case of using the yeast extract as nitrogen source. It was difficult to conclude that the variation of nitrogen source had some effects on the biomass yield. However, the initial sugar concentration had a rather effects on the biomass yield for the sugar concentration of 40 g/L showed 0.27. The nitrogen source that showed the greatest yield of DHA was sodium glutamate.

• 한국미생물·생명공학회지
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• 제24권3호
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• pp.331-335
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• 1996

Characteristics of ethanol fermentation were investigated during the stationary culture of a killer yeast, Saccharomyces cerevisiae B15-1. Specific ethanol production rate reached the maximum level, 1.203 g-EtOH/g-cell-hr, at 150 g/l of the initial glucose concentration. No big differences were obtained in ethanol fermentability based on the initial sugar concentration below 150 g/l. When 200 g/l of sugar was used, fermentability dropped significantly. Although the final cell mass and the amount of ethanol produced were increased, their increase rates were declined according to the increase of initial sugar concentration. It was found that most of the sugar used below 150 g/l of concentration could be changed to ethanol. However, when 200 g/l of sugar was used, some of them remained in the media even after increase of cell mass and fermentation stopped. The ethanol yield was decreased when initial sugar concentration was high, and were increased when the amount of ethanol produced was increased and finally reached the plateau over 60 g/l of ethanol concentration.

• 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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• 제6권1호
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• pp.85-90
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• 1991

Experiments of alcohol fermentation of the yeast,K. fragi1is CBS 1555 were performed to obtain the following results. In these experiments, the initial concentrations of sugar which was composed of inulin and fructose as weight ratio of one to one were 30, 50, 75, 100 and 150g/l and the initial densities of the microorganism were less than 0.5g/l, 10g/1 to 15g/1, and 50g/l. The functional relationship among specific growthrates, sugar concentrations, and alcohol concentrations could be expressed by Aiba-shoda equation and the specific growth rate represented the trend that decreased with increase in the initial concentration of the microorganism. Also, $\mu$max and Ks of Monod's equation could be expressed as the function of initial cell concentration like the following equations. $\mu$max=0.8-0.008X Ks=0.54X+8 In the region that sugar, alcohol and cell concentrations were 10g/1 to 120g/l, 0g/l to 60g/l and 0.5g/l to 50g/l respectively, the differences between the experimental values and the calculated ones for specific growth rate approached to 40% with respect to experimental values at the worst cases, but in most cases, those were distributed in the range of less than 20%.

• KSBB Journal
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• 제4권2호
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• pp.191-196
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• 1989

초기 당농도 50, 79, 110, 190 및 250g/l 각 각에 대한 S, cervisiae SIV-89이 돼지감자 알콜발효특성(비생장속도, 비생성속도, 알콜생성율, 균체생성율, 알콜전환율, 알콜농도의 영향)을 시간의 함수로 규명하여 보았다. 최대 비증식속도 및 최대 알콜 비생성속도는 초기당농도 70내지 80g/l까지는 증가하여 최대값 0.35와 1.98을 나타내었으나 그 이상에서는 감소하였다. 또한 최대 비증식속도 및 최애 알콜 비생성속도가 나타나는 시간은 초기 당농도 증가에 따라 점차로 지연되는 현상을 나타내었다. 균체생성율 $Y_x/_s$알콜생성을$Y_p/_s$의 최대값은 0.15, 0.45이였으며 초기 당농도 증가에 따라 감소 겨향을 나타내었다, 당의 알콜 전환율은 당농도의 증가에 따라 감소하여 당농도 190g/l 이상에서는 70%이하로 떨어졌다. 또한 발효기질 내의 알콜농도가 증가하면 균주의 대사활동이 감퇴되어 알콜농도 70내지 80g/l에 이르게 되며 잔여당농도에 관계없이 균체의 성장 및 알콜 생성이 완전히 중지되는 현상을 나타내었다.

• KSBB Journal
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• 제10권1호
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• pp.55-62
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• 1995

본 연구에서는 균주로 Saccharomyces ceremszae A Tee 24858을, 초기 당 농도로는 60, 90, 120 및 $150g/\ell$ 을, 1회 발효 시간으로는 1시간 또는 2시간을, 초기 균체농도로는 $17.5g/\ell$ 내지 $53.1g/\ell$ 사이의 값을 사용하여 10회 반복 회분식 실험을 수 행하였다. 이 결과로부터 반복 회분식 실험에서의 평균 초기 균체농도와 에탄올 생산성 사이의 함수 관계를 규명 하여 보았다. 초기 균체농도와 에탄올 생산성 사이의 함수 관계는 초기 균체농도가 증가함에 따라 초기 당 농도에 관계없이 에탄올 생산성이 비 션형적 으로 증가하는 함수 관계를 나타내였다. 초기 당 농도가 $60g/\ell$ 이고, 초기 균체농도가 $34.5g/\ell$ 인 경우 발효는 1시간 내에 완료되었으며 균체의 분리, 새로운 기질의 주입 등의 조작을 고려한 총 10회 반복 회분 실험의 에탄올 생산성은 $26.7g/\ell$.hr이었다. 초기 당 농도가 120gjP 이고 초기 균체농도가 5 50.3gj P 인 경우에도 1시간 내에 발효가 완료되었으 며 이때의 에탄올 생산성은 $48.8g/\ell$.hr이었다. 본 연구에서 수행한 8종류의 10회 반복 회분식 실험을 통하여 얻은 최대 에탄융 생산성은 $53g/\ell$.hr이였다.

• KSBB Journal
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• 제4권1호
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• pp.48-56
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• 1989

K.fragilis를 이용한 돼지감자의 알콜발효에서 초기 당농도 및 초기 pH가 발효특성치에 미치는 영향을 실험을 통하여 규명하였으며 그 결과를 종합하면 다음과 같다. 1) 최대 비성장속도($\mu$$_{max})는 초기 당농도 65g/l에서 0.40$hr^-1로서 가장 높은 값을 나타내었다. 2) 최대 비알콜생성속도(V$_{max})는 초기당농도 105g/1에서 1.68g/ghr로서 가장 높은 값을 나타내었는데, 이것은 빠른 균체의 성장이 곧 빠른 생성물 생성의 조건이 아님을 뜻한다고 여겨지며, 저농도 기질에서 기질 및 생성물의 저해를 적게 받는 것을 알 수 있다. 3)균체(Y$_{x/s})및 메탄올수율(Y$_{p/s})은 저농도 기질인 당농도 26g/1에서 각각 0.14, 0.49로서 최대값을 나타내었다. 4)알콜발효능(F)는 기질농도 26, 45g/1에서 97%로서 가장높았고, 잔당의 농도도 5g/1미만이 였다. 5)총팔에탄올생성율(Q)은 고농도 기질인 당농도 215g/1에서 2.78/ghr로서 가장 높았다. 6)효모 K.fragilis가 분비하는 lnulinase의 생성최적 p$^{H}인 5.5에서 최대 비성장속도 0.40, 최대 비알콜 생성속도 1.60, 균체수율 0.096, 에탄올수율 0.49로서 최대 값을 나타내었다.

• 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.