• 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%.

• 한국미생물·생명공학회지
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• 제21권4호
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• pp.354-365
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• 1993

A novel control method with automatic tuning of PID controller parameters has been developed for efficient regulation of dissolved oxygen concentration in fed-batch fermentations of Escherichia coli. Agitation speed and oxygen partial pressure in the inlet gas stream were chosen to be the manipulated variables. A heuristic reasoning allowed improved tuning decisions from the supervision of control performance indices and it coule obviate the needs for process assumptions or disturbance patterns. The control input consisted of feedback and feedforword parts. The feedback part was determined by PID control and the feedforward part is determined from the feed rate. The proportional gain was updated on-line by a set of heuristics rules based on the supervision of three performance indices. These indices were output error covariance, the average value of output error, and input covariance, which were calculated on-line using a moving window. The integral and derivative time constants were determined from the period of output response. The specific growth rate was maintained at a low level to avoid acetic acid accumulation and thus to achieve a high cell density. The specific growthe rate was estimated from the carbon dioxide evolution rate. In fed-batch fermentation, the simutaneous control of dissolved oxygen concentration (at 0.2; fraction of saturated value) and specific growth rate (at 0.25$hr^{-1}$) was satisfactory for the entire culture period in spite of the changes in the feed rate and the switching of control input.

• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.789-793
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• 1999

The effect of acetic acid formation deficiency on recombinant E. coli fermentation was investigated using a mutant strain deficient in acetic acid formation. A mutant strain which does not grow under anaerobic conditions was isolated. The acetic acid production in this strain was negligible in aerobic batch fermentation. The cloned-gene expression in the mutant strain was higher than the wild-type strain. Fed-batch fermentations with controlled specific growth rates were carried out in order to compare the cloned-gene expression between the wild-type and the mutant strains. The expression decreased along with the specific growth rate in both strains. The cloned-gene expression in the mutant strain was 60% higher than in the wild-type strain at the same specific growth rate.

• KSBB Journal
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• 제13권3호
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• pp.289-294
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• 1998

The effects of various step-fortifications of the initial medium with amino acids, glucose, and vitamines on the growth and metabolism of a hybridoma cell line in batch cultures were quantified. Comparisons between the metabolic rates of the various cultivations were made for the exponential growth phase. Fortification of the basal medium resulted in higher cell densities through a prolonged growth phase, but the maximum specific growth rate was not affected. The uptake rate of glutamine increased with the addition of amino acids but did not change upon the addition of glucose or vitamines. The specific glucose consumption decreased slightly with the addition of amino acids but increased production of lactate and {{{{ { NH}`_{4 } ^{ +} }}}}. A reciprocal relationship between the yields of {{{{ { NH}`_{4 } ^{+ } }}}} and lactate indicated a joint regulation of glycolysis and glutaminolysis.

• 상하수도학회지
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• 제33권1호
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• pp.55-62
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• 2019

The respirometric technique has been used to analyze the nitrification process in a sequencing batch reactor(SBR) treating municipal wastewater. Especially the profile of the respiration rate very well expressed the reaction characteristics of nitrification. As the nitrification process required a significant amount of oxygen for nitrogen oxidation, the respiration rate due to nitrification was high. The maximum nitrification respiration rate, which was about $50mg\;O_2/L{\cdot}h$ under the period of sufficient nitrification, was related directly to the nitrification reaction rate and showed the nitrifiers activity. The growth rate of nitrifiers is the most critical parameter in the design of the biological nutrient removal systems. On the basis of nitrification kinetics, the maximum specific growth rate of nitrifiers in the SBR was estimated as $0.91d^{-1}$ at $20^{\circ}C$, and the active biomass of nitrifiers was calculated as 23 mg VSS/L and it was about 2% of total biomass.

• KSBB Journal
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• 제13권5호
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• pp.469-476
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• 1998

Among 31 water-born microbial strains isolated from various sites in Korea, strain DJ-4 was selected as a test organism for toxicity measurements in that its growth was completely inhibited by the presence of 668.4 mg/L of chloroform and 297.5 mg/L of toluene in the liquid LB medium whereas others did not. It was observed that lag periods and specific growth rates of DJ-4 batch vial cultures were prolonged and decreased, respectively, by phenol, benzene, toluene, ethylbenzene, p-xylene, perchloroethylene, trichloroethylene, and chloroform at the concentrations between 3.6 and 417.8 mg/L. There changes were found to be linear with respect to the concentrations of the toxic compounds. From the first-order regression equations, 50% effective concentrations (EC50${\mu}$ for concentrations of toxic compounds causing 50% decrease of specific growth rates and EC50lag for 50% increase of length of lag periods) were calculated for each compounds. By comparing DJ-4 EC50${\mu}$ values with Daphnia LC50's from a literature for benzene, ethylbenzene, toluene, and trichloroethlyene, it was concluded that microbial specific growth could be a new, fast, and reliable parameter for toxicity tests.

• 한국패류학회지
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• 제30권3호
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• pp.227-234
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• 2014

본 연구는 해상가두리의 먹이공급비율에 따른 성장 및 생존율을 조사하고, 실내육상양식의 먹이 공급율과의 비교를 통해 국내 주요 북방전복 양성방법인 해상가두리와 함께 실내 사육 수조의 적정 천연먹이의 공급율을 제안하여 북방전복 생산성 향상을 유도하고자 실시하였다. 먹이공급율은 전복 어체중량을 기준으로 일간공급율 (daily feeding rate, DFR) 5, 10, 15, 20% (5DFR, 10DFR, 15DFR, 20DFR) 를 설정하여, 해상가두리와 실내육상수조에서 2반복으로 13개월간 실시하였다. 해상가두리에서 사육한 전복 (최초 수용 시 평균각장 $54.18{\pm}7.39mm$) 성장에서 각 장과 각폭의 절대성장율 (absolute growth rate, ARG), 일간 성장율 (daily growth rate, DGR) 및 특수생장율 (specific growth rate, SGR) 과 중량의 증중률 (weight gain, WG), 일간증중률 (daily weight gain, DWG) 및 특수증중률(specific weight gain, SWG), 그리고 생존율에서 20DFR이 유의적으로 낮았다 (P < 0.05). 실내육상수조에서 사육한 전복 (최초 수용 시 평균각장 $49.70{\pm}2.28mm$) 의 각장, 각폭의 ARG, DGR, SGR과 중량의 WG, DWG, SWG에서는 5DFR, 10DFR이 유의적으로 높았고 (P < 0.05), 생존율은 20DFR이 유의적으로 낮았다 (P < 0.05). 따라서 해상가두리와 실내육상수조 전복양식 자연먹이의 일간 공급율은 성장과 생존율, 그리고 경제적 측면까지 고려하면 어체중량의 5-10%에서 공급해야 한다.

• 대한환경공학회지
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• 제33권8호
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• pp.591-597
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• 2011

본 연구는 담수미세조류의 일종인 클로렐라를 발광다이오드를 이용하여 효율적으로 배양하기 위한 조건을 찾기 위해 수행되었다. 클로렐라 배양에 최적인 파장을 찾기 위해 청색, 적색, 백색, 그리고 혼합광을 클로렐라가 포함된 반응기에 각각 조사하여 성장속도 및 셀농도를 측정하였다. 적색파장이 클로렐라의 성장에 가장 효율적이었으며, 광량이 증가할수록 성장속도 및 셀농도도 광량에 비례하여 가장 많이 증가하였다. 클로렐라의 초기 농도에 따른 성장속도는 초기 농도가 증가함에 따라 그림자 효과에 의해 감소하였다. 공기 공급에 따른 성장특성을 살펴보기 위해 반응기에 미세공기를 연속적으로 주입하였는데, 반응속도 및 셀농도는 공기를 주입하지 않은 경우에 비해 2배와 10배 증가함을 알 수 있었다. 본 연구를 통해 클로렐라를 효과적으로 배양하기 위해서는 적색파장의 발광다이오드를 광원으로 사용하고 반응기에 공기를 연속적으로 주입하는 것이 효과적임을 알 수 있었다.

• KSBB Journal
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• 제15권6호
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• pp.670-672
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• 2000

Azotobacter vinelandii uwn는 배지에 짝수의 탄소원외에 홀수의 탄소원을 첨가했을 때 생분해성 고분자인 PHBV를 합성한다. 본 실험에서는 propionic acid와 valerie acid를 첨가 한 후 세포생장과 비생장속도를 관찰하였다. Propionic acid 농도가 1.0 -1.5 g/L, valerie acid 농도가 1.0 g/L일 때 세포 생장이 다른 농도에서보다 높았으며, 이때의 비생장속도는 각각 $0.183 hr^{-1}, 0.137 hr^{-1}$이었다. 그리고 이들 유기산을 각각 0 0.75 g/L, 0.5 g/L 혼합하여 배지중에 넣었을 때 비생장속도 는 유기산을 단독으로 첨가한 경우보다 높게 나타났다. 포도당 농도가 10~50 g/L 에서 실험한 결과 20 g/L 일 때 생장 속도가 가장 높았다.

• 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.