• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.241-246
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• 1989

Continuous on-line monitoring of cell concentration and growth rate in aerobic batch fermentation process was carried out by analyzing the exhaust gas composition of tormentor with a quadrupole mass spectrometer. From the mass spectrometric analyses of major gaseous components, i.e. $N_2$, $O_2$, $CO_2$ and $H_2O$, and the material balance equations for oxygen and carbon dioxide, oxygen uptake rate (OUR) rind carbon dioxide evolution rate (CER) were instantaneously calculated using a computer (16-bit IBM PC-AT) interfaced to a quadrupole mass spectrometer. The calculated OUR and CER data were used for the estimation of cell concentration and growth rate of Candida utilis during batch culture. It was found that the cell concentration could be satisfactorily estimated from the data of OUR arid CER during the culture and this method could be successfully und for the continuous monitoring of cell growth and growth rate.

• KSBB Journal
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• v.4 no.3
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• pp.241-245
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• 1989

A carriersupported mycelial growth of Sreptomyces erythreus was applied to erythromycin fermentation sistem using celite as a support material. Hyphal growth through the pore matrices of the materials showed anchorages and provided a stable biofilm growth. When the phospate concentration was limited to 0.8g corn steep liquor/L(corresponding to 40mg KH2PO4/L), the specific production rate of erythromycin was increased from 557$\mu$g/g-cell.hr under unlimited condition to 2, 898 $\mu$g/g-cell.hr. A fluidized-bed bioreactor was operated for erythromycin production by a repeated fed-batch mode. The control of free mycelial concentration and the extension of production phase were considered important to maintain the reactor productivity at a desired level. The erythromycin production under phosphate-limited condition could be maintained for at least 600hrs.

• KSBB Journal
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• v.10 no.4
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• pp.370-373
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• 1995

The major by-products in ethanol fermentation by Saccharomyces cerevisiae were glycerol, acetaldehyde, acetic acid, lactic acid, and formic acid. The effects of these by-products on the cell growth and ethanol production were studied. By adding acetaldehyde or acetic acid in the fermentation broth, the cell growth decreased while the ethanol production increased. But glycerol and lactic acid had nearly no effects on the cell growth and the ethanol production. Acetic acid and acetaldehyde inhibited the cell growth by diminishing the growth rate as well as by prolonging the lag phase. The ethanol yield increased with the elevation of concentrations of acetic acid and acetaldehyde in the fermentation broth. The maximum ethanol yield was obtained for $3g/\ell$ acetic acid and $2g/\ell$ acetaldehyde, respectively.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.277-282
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• 1989

Xanthan gum is a biopolymer produced by Xanthomonas campestris. In xanthan gum fermentation, the fermentation broth changes to highly viscous non-Newtonian fluid as xanthan gum concentration increases. Maximum xanthan gum concentration is limited by high viscosity of the broth since mass transfers of nutrient and oxygen are inhibited. Int this study the mass transfer effects were investigated in batch and fed-batch fermentations at various agitation speeds and by separate oxygen transfer experiments. Xanthan gum production rate was observed to be largely dependent on oxygen transfer coefficient; while cell growth rate was not affected highly by this factor.

• Journal of the Korean Institute of Intelligent Systems
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• v.3 no.3
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• pp.3-18
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• 1993

본 논문에서는 박테리아에서 생성되는 생체 계면활성제인 emulsan의 생산을 위한 유가식 배양에서 에칸을 농도의 제어에 퍼지기법을 적용하였다. 기절저해가 있는 유가식 배양에서 emulsan의 생산을 향상시키기 위해 최대 비성장속도를 갖는 최적 기질농도가 유지되도록 기질인 에탄올의 공급 속도가 조절되어 졌다. 생물반응기에서 Acunetobacter calcoaceticus RAG-1 박테리아를 회분식과 유가식으로 배양 실험하여 최적 에탄올 농도를 구하고, kinetic 모델을 제시하였다. 배양실험의 결과와 지식을 바탕으로 퍼지 규칙을 구성하였다. 퍼지 제어기에서 제어 입력변수는 기질농도의 최적치와 운전치의 오차와 오차의 변화로서 구성되고, 제어 출력변수는 기질 공급 속도의 변화량으로 구성되었다. 멤버쉽 함수를 입력변수의 퍼지 집합화 과정을 통하여 구하였고, 최소-최대법과 무게 중심법을 이용하여 출력 제어값을 구하였다. 유가식 배양의 전산모사와 실험 결과에서 퍼지제어 기법은 최적 기질 농도를 정확히 제어하였으며, emulsan 생산은 향상되었다.

• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.943-950
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• 2003

To identify the functional properties of Hongkuk ju and to improve its brewing process, Hongkuk ju was brewed using different hongkuks (Monascus red koji) made by Monascus purpureus, Monascus anka, Monascus aruneosus, and nuruk. Hongkuk using M. purpureus showed the highest enzyme activity. Hongkuk ju prepared with the M. purpureus hongkuk was fermented most efficiently, and showed the highest Hunter value. Hongkuk ju showed significant levels of phenolic compounds, electron donating ability, nitrate-scavenging activity, and ACE inhibition activity. In particular, Hongkuk ju made with M. purpureus showed the highest value among the wines of this study.

• KSBB Journal
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• v.20 no.1 s.90
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• pp.60-65
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• 2005

The objective of this work was to evaluate a solid-state fermentation process for the practical production of arachidonic acid(AA) by Mortierella alpina ATCC 32222. In the present investigation, batch culture kinetics for both submerged- and solid-state fermentations was carried out at $25^{\circ}C$ to identify the relationship between growth and arachidonic acid (AA) production. Glucose and yeast extract were used in submerged fermentations by using flasks, while rice bran was used as a sole raw material in the other type of fermentations by using a series of Petri dishes. It was evident that a mixed-growth associated pattern existed between the two variables, irrespective of modes of fermentations. The effect of carbon to nitrogen (CfN) ratio on AA production in solid-state fermentation was studied in the range of 6.5 - 20. As a result, an optimum condition was found to be 6.5. Supplementary carbon source was not necessary to meet the optimum C/N ratio. Unlike the Previous results obtained by other researchers, a supplement of sodium glutamate up to $4\%$ (w/w) to the rice bran medium did not have a positive effect on the AA productivity. However, an increase in AA productivity was obtained with the rice bran medium supplemented with sesame oil.

• Microbiology and Biotechnology Letters
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• v.7 no.2
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• pp.71-74
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• 1979

The growth characteristics of Methylomonas methanolica YUFE 101, isolated from sewage samples, have been studied. conclusions of the study were; (1) Optimum cultivation pH and temperature are 6.3 and 32.5$^{\circ}C$ respectively (2) The specific oxygen uptake rate was 332 $\mu$ι/mg-dry weight/hr. (3) The maximum specific growth rate was 0.19 h $r^{-1}$ and celluar yield was 0.43 g-dry cell/g-methanol in batch culture, (4) The maximum biomass productivity achieved was 0.21 g-dry cel1/ι/hr at a dillution rate of 0.1 h $r^{-1}$ during continuous cultivation. (5) The contents of crude protein and total nucleic acid in the dry cell were 73 ％ and 12 ％ respectively.

• KSBB Journal
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• v.4 no.2
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• pp.172-176
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• 1989

The alcohol fermentation was carried out to study the effect of aeration and unsaturated fatty acids added on the ethanol tolerance of Saccharomyces cerevisiae STV89 and Kluyveromyces fragilis CBS397. The cell growth rate and ethanol production rate was stimulated by aeration and the cell mass production and ethanol production were also substantially improved. With respect to strains, the maximum specific growth rate and overall ethanol productivity of K. fragilis under aerated condition were 6.4 fold and 4.4 fold higher than those of strictly anaerobic condition, although those of S. cerevisiae were increased 1.7 times and 2.3 times by aeration. The addition of ergosterol, linoleic acid and oleic acid also improved the cell growth and ethanol production of S. cerevisiae and K. fragilis. Thus it was found that oxygen and unsaturated fatty acids added played a decisive role on the increase of ethanol tolerance of yeast strains.

• Korean Journal of Food Science and Technology
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• v.26 no.3
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• pp.204-212
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• 1994

To estimate the possibility of wine-making with Korean dried persimmon, its homogenized and filtered solution was fermented at $15^{\circ}C$ and $25^{\circ}C$ for 12 weeks with Saccharomyces cerevisiae (Japan Alcoholic Beverage Association N0.7). Sugars of dried persimmon were mainly composed of 27.02% of glucose, 19.81% of fructose and 5.12% of mannose. In the fermentation at $25^{\circ}C$, glucose was almost completely consumed in 8 days, but fructose and mannose were consumed up to 64% and 74%, respectively, in the same period and were not utilized any more afterwards. In the fermentation at $15^{\circ}C$, 75% of glucose, 20% of fructose and 49% of mannose were consumed in 8 days and these sugars were continuously utilized for 12 weeks. Organic acids in the homogenized and filtered solution were levulinic acid (148.6 mg%), 4-methylvaleric acid (73.5 mg%), oxalic acid (28.7 mg%), acetic acid (8.5 mg%), N-butyric acid (8.4 mg%) and succinic acid (6.7 mg%). Irrespective of fermentation temperature, levulinic acid rapidly reduced according to progression of fermentation. Oxalic acid, N-butyric acid and succinic acid decreased at 2nd day of fermentation, and then increased at 4th and 6th days and subsequently decreased again under the levels of the solution. Acetic acid and 4-methylvaleric acid increased with the proceeding of fermentation and at 12th week of fermentation these contents were more than those of the solution. The contents of total free amino acid significantly reduced at 2th day of fermentation and then increased to the level of the solution at 12th week irrespective of fermentation temperature. Ethanol content rapidly increased to the levels of 5.3(v/v) at $15^{\circ}C$ and 9.4%(v/v) at $25^{\circ}C$ to 8th day after fermentation, but at 12th week its content was 14.5%(v/v) at $15^{\circ}C$ and 9.4%(v/v) at $25^{\circ}C$. The higher alcohots identified were 2-methyl-l-propanol, 3-methyl-ibutanol, 2-methyl-l-butanol and 2-methyl-2-propanol and the range of those contents was from 0.001% (v/v) to 0.06%(v/v). The color of the wine fermented at $15^{\circ}C$ was slightly superior but flavor and taste were slightly superior in the wine fermented at $25^{\circ}C$.