• 한국수소및신에너지학회논문집
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• 제24권1호
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• pp.20-28
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• 2013

Photobiological hydrogen production by nitrogen-fixing unicellular cyanobacteria has long been considered to be an environmentally sound and very promising method for the future supply of renewable clean energy. Using six Korean nitrogen-fixing unicellular cyanobacterial strains and the Synechococcus sp. strain Miami BG043511 we performed cultivation experiments to find out the strain-specific optimal temperature for population growth and $H_2$ production. Under $20^{\circ}C$ the population growth of all the tested strains was significantly retarded in contrasts to the faster and higher growth under 25, 30 or $35^{\circ}C$. The highest growth rates in all the 7 strains were measured under $30^{\circ}C$ while the maximal biomass yields were under $30^{\circ}C$ (strains CB-MAL 026, 054, and 055) or $35^{\circ}C$ (strains 002, 031, 058, and Miami BG043511). The difference between the maximal biomass yields at $30^{\circ}C$ and $35^{\circ}C$ was not greater than 10%. The quantity of photobiologically produced $H_2$ was only slight larger under $35^{\circ}C$ than that under $20^{\circ}C$. Our result may suggest a two-step process of $H_2$ production which includes rapid and sizable production of biomass at $30^{\circ}C$ and the following high $H_2$ production at $20^{\circ}C$ by the test strains of marine nitrogen-fixing unicellular cyanobacteria.

• KSBB Journal
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• 제10권2호
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• pp.176-182
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• 1995

Methylobacterium organophilum을 이용하여 다당류(메틸란)와 poly-${\beta}$-hydroxybutyrate(PHB)의 생산에 영향을 주는 환경 및 생리적 인자들을 조사하였다. PHB 축적을 위하여는 $38^{\circ}C$, 다당류의 생산을 위하여는 $30^{\circ}C$가 최적이었다. pH의 경우는 P PHB의 축적은 pH 7 ~ 8, 다당류의 생산은 pH 6~7 이 최적이였다. 질소원 제한 상태하에서의 $Mo^{2+}, Mg^{2+} 또는 Mn^{2+}$ 등의 결핍조건에셔는 질소원만의 제한조건보다 P PHB 축적은 증가하였으나, 다당류 생산은 감소하였 다. 질소원의 제한없이 $K^+$만의 결핍조건에서는 균 체증식도 억제되었고 다당류도 생성되지 않았지만 건조균체당 PHB 함량은 60%까지 증가하였다. PHB와 다당류의 동시 생산을 위한 C/N 비율의 효 는 C/N 비율이 높을수록 질소원의 제한효과 때문에 균체증식은 감소되었지만 건조균체량당 PHB 함량과 다당류의 생성은 현저히 증가하였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.199-202
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• 2000

Optimization of submerged culture conditions for the production of exo-biopolymer from Paecilomyces japonica was studied. Maltose, yeast extract and potassium phosphate were the most suitable sources of carbon, nitrogen, and inorganic salt, respectively, for both production of the exo-biopolymer and mycelial growth. The optimal culture conditions in flask culture were pH 5.0, $25^{\circ}C$ and 150 rpm in a meidum containing of 30 g maltose, 6 g yeast extract, 2 g polypeptone, 0.5 g $K_2HPO_4$, 0.2 g $KH_2PO_4$, 0.2 g $MnSo_4\;{\cdot}\;5H_2O$, 0.2 g $MgSO_4\;{\cdot}\;7H_2O$ in 1-L distilled water. Exo-biopolymer production and mycelial growth in the suggested medium were significantly increased in a 2.5-L jar fermentor, where the maximum biopolymer concentration was 8 g/1.

• Journal of Microbiology and Biotechnology
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• 제28권12호
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• pp.1982-1991
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• 2018

Ethanol accumulation inhibited the growth of Saccharomyces cerevisiae during wine fermentation. Autophagy and the release of reactive oxygen species (ROS) were also induced under ethanol stress. However, the relation between autophagy and ethanol stress was still unclear. In this study, expression of the autophagy genes ATG1 and ATG8 and the production of ROS under ethanol treatment in yeast were measured. The results showed that ethanol stress very significantly induced expression of the ATG1 and ATG8 genes and the production of hydrogen peroxide ($H_2O_2$) and superoxide anion (${O_2}^{{\cdot}_-}$). Moreover, the atg1 and atg8 mutants aggregated more $H_2O_2$ and ${O_2}^{{\cdot}_-}$ than the wild-type yeast. In addition, inhibitors of the ROS scavenging enzyme induced expression of the ATG1 and ATG8 genes by increasing the levels of $H_2O_2$ and ${O_2}^{{\cdot}_-}$. In contrast, glutathione (GSH) and N-acetylcystine (NAC) decreased ATG1 and ATG8 expression by reducing $H_2O_2$ and ${O_2}^{{\cdot}_-}$ production. Rapamycin and 3-methyladenine also caused an obvious change in autophagy levels and simultaneously altered the release of $H_2O_2$ and ${O_2}^{{\cdot}_-}$. Finally, inhibitors of the mitochondrial electron transport chain (mtETC) increased the production of $H_2O_2$ and ${O_2}^{{\cdot}_-}$ and also promoted expression levels of the ATG1 and ATG8 genes. In conclusion, ethanol stress induced autophagy which was regulated by $H_2O_2$ and ${O_2}^{{\cdot}_-}$ derived from mtETC, and in turn, the autophagy contributed to the elimination $H_2O_2$ and ${O_2}^{{\cdot}_-}$.

• Asian-Australasian Journal of Animal Sciences
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• 제19권3호
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• pp.376-380
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• 2006

An experiment was conducted to study the effect of temperature and pH on in vitro nutrient degradability, volatile fatty acid profile and methane production. The fermenter used was the semi-continuous system, known as the rumen simulation technique (RUSITEC). Sixteen cylinders were used at one time with a volume of 800 ml, the dilution rate was set at 3.5%/hour, the infused buffer being McDougall's artificial saliva. Basal diet (9.6 g DM) used in RUSITEC consisted of (DM) 6.40 g Timothy hay, 1.86 g crushed corn and 1.34 g soybean meal. The food for the fermentation vessel was provided in nylon bags, which were gently agitated in the liquid phase. The experiment lasted for 17 d with all the samples taken during the last 5 d. Treatments were allocated at random to four vessels each and were (1) two temperature levels of $39^{\circ}C$ and $41^{\circ}C$ (2) two pH levels of 6.0 and 7.0. The total diet contained ($g\;kg^{-1}$ DM) 957 OM, 115 CP and $167MJ\;kg^{-1}$ (DM) GE. Although increase in temperature from $39^{\circ}C$ to $41^{\circ}C$ reduced degradation of major nutrients in vitro, it was non-significant. Interaction effect of temperature with pH also reflected a similar trend. However, pH showed a significant (p<0.05) negative effect on the degradability of all the nutrients in vitro. Altering the in vitro pH from 7 to 6 caused marked reduction in DMD from 60.2 to 41.8, CPD from 76.3 to 55.3 and GED from 55.3 to 35.1, respectively. Low pH (6) depressed total VFA production (61.9 vs. 34.9 mM) as well as acetate to propionate ratio in vitro (from 2.0 to 1.5) when compared to pH 7. Compared to pH 7, total gas production decreased from 1,841 ml to 1,148 ml at pH 6, $CO_2$ and $CH_4$ production also reduced from 639 to 260 ml and 138 to 45 ml, respectively. This study supported the premise that pH is one of the principal factors affecting the microbial production of volatile fatty acids and gas. Regulating the ruminal pH to increase bacterial activity may be one of the methods to optimize VFA production, reduce methane and, possibly, improve animal performance.

• 한국미생물·생명공학회지
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• 제27권1호
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• pp.62-69
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• 1999

Clostridium butyricum NCIB 9576 evolved hydrogen gas and produced various organic acids from glucose, lactose, starch, and glycerol. Total amount of hydrogen gas produced from 1 and 2% glucose were 630 and 950ml $H_2$/l-broth, respectively, for the first 24 hrs of incubation and the maximum hydrogen production rates were 42 and 94ml $H_2$/hr/1-broth, respectively. Teh initial pH 6.8 decreased to 4.2~4.5 during the first 12~16 hrs of fermentation when the pH was not controlled, resulting in ceasing the cell growth and hydrogen evolution and in degradation of 82 and 40% glucose after 24hrs of incubation from 1 and 2% glucose, respectively. When pH was controlled to 5.5, glucose was consumed completely and resulted in increasing hydrogen production approximately 38~50% compared to the experiments without the pH control. C. butyricum NCIB 9576 produced hydrogen gas approximately 644, 1,700 and 3,080 ml $H_2$/l-broth with 0.5, 1 and 2% lactose, respectively and the maximum hydrogen production rates were 41, 141 and 179ml $H_2$/hr/l-broth, respectively. All of the lactose added was degraded completely during fermentation even though pH was not controlled. C. butyricum NCIB 9576 produced 183 and 709ml $H_2$/l-broth with 0.1 and 0.5% starch for 48 hrs, respectively, when pH was not controlled. The maximum rates of hydrogen gas production were 43 and 186ml $H_2$/l-broth, respectively and 80~100% of starch added was fermented. Approximately 107ml $H_2$/l-broth was produced using 1% glycerol by C. butyricum NCIB 9576 and the pH was maintained higher than 6.1 during fermentation without pH control. The degradation of glucose, lactose, starch and glycerol by C. butyricum NCIB 9576 were affected by the pH of fermentation broth and the organic acids released during fermentation. The pH of feremtntation broth dropped to 4.2~4.6 after 12~14 hrs incubation when glucose was used as a substrate while pHs were maintained above pH 5 under the same experimental conditions when lactose, starch and glycerol were used. The organic solvents and acids produced during glucose fermentation were mainly ethanol, butyrate, acetate and a little of propionate, while butyrate was the main organic acids during the lactose, starch, and glycerol fermentation by C. butyricum NCIB 9576.

• Journal of Microbiology and Biotechnology
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• 제17권2호
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• pp.313-319
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• 2007

The nutritional medium requirement for biosurfactant production by Bacillus licheniformis K51 was optimized. The important medium components, identified by the initial screening method of Plackett-Burman, were $H_3PO_4,\;CaCl_2,H_3BO_3$, and Na-EDTA. Box-Behnken response surface methodology was applied to further optimize biosurfactant production. The optimal concentrations for higher production of biosurfactants were (g/l): glucose, $1.1;NaNO_3,\;4.4;MgSO_4{\cdot}7H_2O,\;0.8;KCl,\;0.4;CaCl_2,\;0.27;H_3PO_4,\;1.0ml/l;\;and\;trace elements\;(mg/l):H_3BO_3,\;0.25;CuSO_4,\;0.6;MnSO_4,\;2.2;Na_{2}MoO_4,\;0.5;ZnSO_4,\;6.0;FeSO_4,\;8.0;CoCL_2,\;1.0;$ and Na-EDTA, 30.0. Using this statistical optimization method, the relative biosurfactant yield as critical micelle dilution (CMD) was increased from $10{\times}\;to\;105{\times}$, which is ten times higher than the non-optimized rich medium.

• 한국식품과학회지
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• 제8권1호
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• pp.33-41
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• 1976

1. 유기질소원(有機窒素源)으로는 soybean meal, 무기질소원(無機窒素源)으로는 $(NH_4)_2SO_4$가 lipase생산(生産)에 가장 효과(效果)이었다. 2. 배양중(培養中) 배지(培地)의 pH저하(低下)를 이르키는 xylose, glucose, fructose, galactose, mannose, maltose, soluble starch, dextrin을 탄소원(炭素源)으로 첨가(添加)하였을 때 lipase 생산(生産)이 심(甚)하게 저해(沮害)되었다. sucrose는 lipase생산(生産)을 저해(沮害)하지 않았으나 첨가효과(添加效果)는 인정(認定)되지 않았다. 3. 인산염(燐酸鹽)으로서는 $K_2HPO_4$, 마그네슘염(鹽)으로서는 $MgSO_4{\cdot}7H_2O$가 lipase생산(生産)에 가장 효과적(效果的)이었다. 4. Olive유(油), 대두유(大豆油) 및 야자유(油)의 첨가(添加)는 lipase생산(生産)을 증가(增加)시켰으며 1% olive유(油) 첨가시(添加時) lipase생산(生産)이 50% 증가(增加)되었다. 5. yeast extract $0.05{\sim}0.07%$첨가시(添加時) lipase생산(生産)이 약간 증가(增加)되었다. 6. 본균(本菌)의 lipase생산(生産)에 가장 적합(適合)한 배지(培地)는 soybean meal 2%, $K_2HPO_4$ 0.5%, $(NH_4)_2SO_4$ 0.1%, $MgSO_4{\cdot}7H_2O$ 0.05%, yeast extract 0.05%, olive유(油) 1%의 조성(組成)의 것으로서 최적배양조건하(最適培養條件下)에서 48시간(時間) 배양시(培養時)에 lipase생산(生産)이 최고(最高)에 도달(到達)하였다.

• 한국응용곤충학회지
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• 제28권2호
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• pp.69-75
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• 1989

B. thuringiensis subsp. kurstaki HD-1을 아밀라제 생산배지에 $32^{\circ}C$로 24시간 배양하였을 때 아밀라제 활성은 0.40 units/ml 였고, 50mM EDTA에 의하여 활성이 억제되었으며, 기본배지에 soluble starch와 $Ca^{2+}$, $Mg^{2+}$, $Mn^{2+}$을 첨가했을 때 활성이 비교적 높았고, pH6.5와 7.0 사이에서, 온도 $55^{\circ}C$에서 비교적 활성이 높았다. 아밀라제 생산을 위한 최적 배지로는 0.2% soluble starch, 1.0% bacto-peptone, 0.3% beef extract, 0.5% NaCl, 0.3% $K_{2-}$$KH_{2}PO_{4}$, 0.012% CaCl.$2H_{2}O$, 0.005% $MnSO_{4}$.$H_{2}O$, 0.03% $MgSO_{4}$.$7H_{2}O$이었다. 효소 용액을 에 $HPO_{4}$, 0.1% 탄올 침전시켜 5ml의 0.1M 인산염 완충액에 용해한 용액의 비활성은 2.01 units/mg였고, starch에 대한 효소의 Km 값은 0.80 mg/ml였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.720-722
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• 2009

This work is mainly focused at developing the hydrogen production unit with the capacity of 20 $Nm^3/h$ of high purity hydrogen. At present steam reforming of natural gas is the preferable method to produce hydrogen at the point of production cost. The developed hydrogen production unit composed of natural gas reformer and pressure swing adsorption system. To improve the thermal efficiency of steam reforming reactor, the internal heat recuperating structure was adopted. The heat contained in reformed gas which comes out of the catalytic beds recovered by reaction feed stream. These features of design reduce the fuel consumption into burner and the heat duty of external heat exchangers, such as feed pre-heater and steam generator. The production rate of natural gas reformer was 41.7 $Nm^3/h$ as a dryreformate basis. The composition of PSA feed gas was $H_2$ 78.26%, $CO_2$ 18.49%, CO 1.43% and $CH_4$ 1.85%. The integrated production unit can produce 21.1 $Nm^3/h$ of high-purity hydrogen (99.997%). The hydrogen production efficiency of the developed unit was more than 58% as an LHV basis.