• Food Science and Biotechnology
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• 제18권6호
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• pp.1342-1350
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• 2009

This paper investigates the production and optimization of $\beta$-galactosidase enzyme using synthetic medium by Kluyveromyces lactis NRRL Y-8279 in stirred tank bioreactor. Response surface methodology was used to investigate the effects of fermentation parameters on $\beta$-galactosidase enzyme production. Maximum specific enzyme activity of 4,622.7 U/g was obtained at the optimum levels of process variables (aeration rate 2.21 vvm, agitation speed 173.4 rpm, initial sugar concentration 33.8 g/L, incubation time 24.0 hr). The optimum temperature and pH of the $\beta$-galactosidase enzyme produced under optimized conditions were $37^{\circ}C$ and pH 7.0, respectively. The enzyme was stable over a pH range of 6.0-7.5 and a temperature range of $25-37^{\circ}C$. The $K_m$ and $V_{max}$ values for O-nitrophenol-$\beta$-D-galactopyranoside (ONPG) were 1.20 mM and $1,000\;{\mu}mol/min{\cdot}mg$ protein, respectively. The response surface methodology was found to be useful in optimizing and determining the interactions among process variables in $\beta$-galactosidase enzyme production. Hence, this study fulfills the lack of using mathematical and statistical techniques in optimizing the $\beta$-galactosidase enzyme production in stirred tank bioreactor.

• Journal of Microbiology
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• 제45권3호
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• pp.199-204
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• 2007

The objective of this study was to evaluate the effect of soluble carbohydrates (glucose, cellobiose), pH (6.0, 6.5, 7.0), and rumen microbial growth factors (VFA, vitamins) on biohydrogenation of linoleic acid (LA) by mixed rumen fungi. Addition of glucose or cellobiose to culture media slowed the rate of biohydrogenation; only 35-40% of LA was converted to conjugated linoleic acid (CLA) or vaccenic acid (VA) within 24 h of incubation, whereas in the control treatment, 100% of LA was converted within 24 h. Addition of VFA or vitamins did not affect biohydrogenation activity or CLA production. Culturing rumen fungi at pH 6.0 slowed biohydrogenation compared with pH 6.5 or 7.0. CLA production was reduced by pH 6.0 compared with control (pH 6.5), but was higher with pH 7.0. Biohydrogenation of LA to VA was complete within 72 h at pH 6.0, 24 h at pH 6.5, and 48 h at pH 7.0. It is concluded that optimum conditions for biohydrogenation of LA and for CLA production by rumen fungi were provided without addition of soluble carbohydrates, VFA or vitamins to the culture medium; optimum pH was 6.5 for biohydrogenation and 7.0 for CLA production.

• 한국식품영양과학회지
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• 제24권1호
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• pp.141-146
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• 1995

본 연구의 목적은 이온음료 제조를 위한 동치미 최적 담금 조건을 설정하고자 각 담금 조건 소금농도 2.0, 2.4%, 숙성온도 0.5, $10^{\circ}C$에 따른 동치미액의 성분 분석을 행하였다. pH 감소속도 및 총산도는 동치미의 숙성온도가 높을수록 빠른 증가경향을 나타내었으며 유기산은 lactic acid, citric acid, malic acid가 검출되었고, 그 중 lactic acid 생성량이 가장 많았으며 succinic acid는 $0^{\circ}C$ 숙성 말기에 미량 검출되었다. 젖산균은 염도에 관계없이 숙성초기에 증가하다가 감소하는 경향을 나타내었고 젖산균이 증가하는 기간에 lactic acid 함량도 증가하는 경향을 나타내어 젖산균수와 lactic acid 함량 변화는 일치하는 경향을 보여주고 있다. 휘발성 성분은 3-methyl pentane, ethyl thioethene, 2,3-diaza-indolizine, dimethyl disulfide 등으로 추정되었다. 이온 음료 제조를 위한 최적 담금 조건은 비휘발성 유기산이 최대로 검출되는 최적 숙기인 pH 4.2~3.9, 산도 0.1~0.4에 이르는 동치미로 $0^{\circ}C$에서 24~29일, $5^{\circ}C$에서 9~12일, $10^{\circ}C$에서 16~22 숙성시킨 동치미를 최적 담금조건으로 설정하고자 한다.

• 한국주조공학회지
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• 제29권5호
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• pp.213-219
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• 2009

Optimum conditions for production of semi-solid Al-Zn-Mg alloy billets was carried out by the Taguchi design method. And, Al-Zn-Mg alloy billets contained Sc (free, 0.1 and 0.3 mass %) were fabricated at optimum conditions. Evolution of microstructure in semi-solid state was investigated through various liquid fractions, holding times and holding temperatures. The Al-Zn-Mg alloy billets reheated at $615^{\circ}C$ during 30min are grain growth and it was fractured due to increasing liquid fraction before quenching. And, during reheating up to $600^{\circ}C$, grain growth of Al-Zn-Mg alloy billets contained Sc (0.1 and 0.3 mass %) was not occurred in comparison with those of Al-Zn-Mg alloy without Sc. It was thought that $Al_3Sc$ phases have a pinning effect in grain boundary and Sc content of 0.1 mass% is able to inhibit grain growth effectively through reheating process.

• 한국축산시설환경학회지
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• 제4권2호
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• pp.113-126
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• 1998

This study was conducted to develop pig-housings based on the forecasting models of swine production, the weather conditions, and so on in Korea. The Korean pig-housings were developed according to the following basis : 1. They should be suitable to domestic weather conditions. 2. They should be designed based on the forecasting models of swine production of farrow to finish operation among the forecasting models of swine production in Korea. 3. Proper environments should be offered to pigs according to the growth. 4. The environmental control, the treatment of swine wastewater, and so on should be interrelated. 5. Manual energy should be saved by effective arrangements of pig-housings. In the future, performance test of the Korean pig-housings and development of facility automation systems which are suitable to these should be accomplished.

• 한국미생물·생명공학회지
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• 제21권5호
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• pp.486-493
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• 1993

A gram(+) bacteria that produced microbial flocculant was isolated from soil and classified as a Bacillus species and named as Bacillus sp. A56. The culture conditions of the strain for fluocculant production were studied in a shake flask. Optimum temperature and initial pH for flcculant production were 30C and 6.5, respectively. The optimized medium has gollowing composition: glucose 20g/l, NH4NO3 0.5g/l, K2HPO4 1.0g/l, KH2PO4 0.8g/l, MgSO4.7H2O 0.2g/l, MnSO4.4-6H2O 0.3g/l, CaCO3 0.5g/l, yeast extract 0.3g/l, tryptone 0.3g/l in tap water.

• 한국식품영양과학회지
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• 제27권4호
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• pp.639-647
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• 1998

This study was carried out to produce the maltooligosaccharides directly from the culture medium containing high concentration of soluble starch as carbohydrate source by Bacillus cereus IAM 1072. Optimum conditions for the production of maltopentaose and maltooligosaccharides were predicted as 10.62 and 10.92 in C/N ration, 115.74 and 116.51 rpm in agitation speed, 30.19 and 30.9$0^{\circ}C$, respectively. And at these conditions, products of maltopentaose and maltooligosaccharides were 23.23 and 50.33g/L, respectively. From the results of continuous culture for maltopentaose, the productivity increased up to 6.9 times, showing 6.6g/L/hr compared with 0.96g/L/hr batch culture. Maltopentaose showed lower sweetness at 3% concentration representing 1/5 of that sugar. Also, swelling power of maltooligosaccharides was reached to the same point with sugar after fermentation.

• Journal of Microbiology
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• 제43권1호
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• pp.38-43
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• 2005

Lactic acid production parameter optimization using Lactobacillus amylovorus NRRL B-4542 was performed using the design of experiments (DOE) available in the form of an orthogonal array and a software for automatic design and analysis of the experiments, both based on Taguchi protocol. Optimal levels of physical parameters and key media components namely temperature, pH, inoculum size, moisture, yeast extract, $MgSO_4{\cdot}7H_20$, Tween 80, and corn steep liquor (CSL) were determined. Among the physical parameters, temperature contributed higher influence, and among media components, yeast extract, $MgSO_4{\cdot}7H_20$, and Tween 80 played important roles in the conversion of starch to lactic acid. The expected yield of lactic acid under these optimal conditions was 95.80% and the actual yield at optimum conditions was 93.50%.

• Mycobiology
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• 제36권3호
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• pp.183-189
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• 2008

The production of aerial conidia of Lecanicillium lecanii 41185, a highly virulent fungus, by solid-state fermentation was studied for use as a biocontrol agent against aphids. Among several agro-industrial solid media, steamed polished rice was found to produce the highest amount of aerial conidia. The optimal conditions for aerial conidia production were determined to be a 28.5% moisture content in the rice, 25$^{\circ}C$ culture temperature, rice pH of 6.0, 75% ambient relative humidity, 4-dold seeding culture, 0.6% $KNO_3$, and 12 d of culture time. The conidia yield increased from $5.7\times10^9$ conidia/g polished rice to 18.2 $18.2\times10^9$ conidia/g polished rice following application of these optimized conditions.

• 한국환경보건학회지
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• 제29권3호
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• pp.72-78
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• 2003

In the process of producing chitosan from crustacean shell, the use of excessive acid and alkli is causing the problems of environmental pollution and of production cost. In this study, one way to solve these problems is to cultivate fungi, then, to extract chitosan from the cell wall. By means of flask incubation and batch cultivation, the optimum cultivation conditions for mass production of continuous cultivation was found. Four strains used for the production of fungal chitosan were Gongronella butleri IF08080, Absidia coerulea IF05301, Rhizopus delemar IF04775, Mucor tuberculisporus IF09256. In flask incubation to select strain of producing much chitosan by means of experiment of the effect of initial pH, Absidia coerulea IFO 5301 had highest yield in FCs, 258.1 $\pm$ 47.3 mg/200 $m\ell$l at pH 6.5. In flask incubation under the optimum cultivation condition, temperature 27$^{\circ}C$, culture time 6days, glucose 2%, peptone 1%, (NH$_4$)$_2$ SO$_4$ 0.5%, $K_2$HPO$_4$ 0.1 %, Nacl 0.1 %, MgSO$_4$ㆍ7$H_2O$ 0.05%, CaCl$_2$ㆍ2$H_2O$ 0.01 %, the yield of DCW brought the highest yields. In batch bioreactor, the optimum cultivation condition was that cell suspended solution was 70 $m\ell$, aeration rate 0.5 l/min, agitation rate 800 rpm, culture time 36 hr. In continuous bioreactor, the optimum substrate flow rate was 4 ι/day.