• Microbiology and Biotechnology Letters
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• v.22 no.1
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• pp.106-113
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• 1994

A novel method for production of concentrated purity maltose using swollen extruded corn starch was investigated. Degree of gelatinization of extruded starch suitable for maltose formation was found to be around 70%. The optimal amiunt of enzyme was 400 unit fungal $\alpha $-amylase per g of starch, and the reaction time was 12 hours. At extruded starch concentration of 300 g/l(w/v), maltose concentration and content were reached up to 220 g/l(w/v) and 77%(w/w), respectively. The maltose forming reaction was also successfully proceeded at high starch concentration of 700 g/l(w/v), however, the conversion yield and content were decreased. By the addition of extruded starch by fed-batch wise, the maltose concentration, purity, and conversion yield could be improved up to 465 g/l(w/v), 70%(w/w), and 0.63, respectively. The investigated maltose production process seems to have many potential advantages over the conventional process utilizing liquefied starch, and the feasibility for industrial application needs to be evaluated.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.41-44
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• 2000

Fermentation characteristics of recombinant Saccharomyces cerevisiae containing the xylose reductase gene from Pichia stipitis were analyzed in an attempt to convert xylose to xylitol, a natural five-carbon sugar alcohol used as a sweetener. Xylitol was produced with a maximum yield of 0.95 (g xylitol/g xylose consumed) in the presence of glucose that is used as a cosubstrate for cofactor regeneration. However addition of glucose caused inhibition of xylose transport and accumulation of ethanol. Such problems were solved by adopting glucose-limlted fed-batch fermentation. This process done with S, cerevisiae EHl3.15:pY2XR at$30\;^{\circ}C$ resulted in 105.2g/L xylitol concentration with maximum productivity of 1.69 g $L^{-1}$ $hr^{-1}$.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.145-148
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• 2003

High concentration of glutathione(GSH) has been found in some species of yeast, of which Saccharomyces cerevisiae is used for commercial fermentative production. In this study, we have investigated the optimal conditions of production which could increase the GSH productivity and used it to maximize the production of GSH in fed-batch culture of Sacchromyces cerevisiae. Fermentation process have been also real time monitored by a 2-dimensional fluorescence sensor.

• Journal of Environmental Health Sciences
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• v.33 no.6
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• pp.493-496
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• 2007

The influences of contact time and ratio of food to microorganism (F/M) on uptake of wastewater organic matter in a short contact process were investigated using three activated sludge batch reactors fed with synthetic wastewater, sewage and livestock wastewater. About 64% of influent soluble chemical oxygen demand (SCOD) in the synthetic wastewater and 61% of SCOD in the sewage and 43% of SCOD in the diluted livestock wastewater were adsorbed into the activated sludge within 30 min. The specific mass of organic matter uptaken in the synthetic wastewater was 55 mg SCOD/g mixed liquor suspended solids (MLSS). In the same manner, 20 and 14 mg SCOD/g MLSS were calculated as the values in the sewage and livestock wastewater, respectively.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3274-3275
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• 1999

This paper presents a new method of spacer assembly using anodic bonding method which is very simple and clean. The spacer having $100{\mu}m(W){\times}2.1{\mu}m(H)$ was bonded on amorphous silicon film of anode plate. Then, the vertical-type electrode was used for assembling of spacer in high voltage field emission display. In these results, we suggested that the vertical-type electrode provided spacer alignment for high aspect ratio and more simple batch process than conventional method.

• Microbiology and Biotechnology Letters
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• v.17 no.5
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• pp.504-509
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• 1989

Fermentation condition of Streptococcus lactis IFO 12007 for nisin production was examined. The optimal glucose concentration was 60g/ι. The pH and temperature optimum were 6.5 and 31$^{\circ}C$, respectively. The maximum nisin activity in batch culture was 2000IU/$m\ell$. The fermentation quotients after 7 hours of fermentation in batch culture were; specific glucose uptake rate:0.59g/g/h , specific nisin productivity: 34924IU/g/h, product yield: 5944IU/g, growth yield:0.24, biomass:4.81g/ι. The specific growth rate was affected by pH and temperature and the activation energy for growth was 1.35kcal/mole. pH control was essential for nisin production. Fed-batch culture using 20g/$\ell$ glucose medium produced 1420IU/$m\ell$ after 14 hours. The continuous culture could be operated at below 0.38h$^{-1}$ for nisin production. The steady state nisin concentration and specific nisin productivity were 740IU/$m\ell$ and 45000IU/g/h. The growth yield and maintenance energy were 0.144 and 207mg glucose/g-cell/h.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.451-455
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• 2006

Heterotrophic biomass yield coefficients, $Y_H$, for aerobic, anoxic and anaerobic reactors were successfully estimated for the two wastewater treatment plants, where one plant was operating in the $A^2/O$ process and the other was operating in the 4-stage BNR process. The estimation of $Y_H$ was undertaken by plotting the biomass COD concentrations versus the soluble COD concentrations in order to calculate the ${\Delta}biomass$ COD/ ${\Delta}soluble$ COD in each batch reactor. The batch reactors employed in this study were fed by filtered influent and mixed liquors in the ratio of 10:1, and operated in the aerobic, anoxic and anaerobic conditions, which represented the actual operating conditions for the $A^2/O$ and 4-stage BNR process. The average $Y_H$ values of the aerobic, anoxic and anaerobic reactor for the $A^2/O$ process were 0.52, 0.41 and 0.18 mg COD/mg COD, respectively, and those for the 4-stage BNR process were 0.58, 0.40 and 0.20 mg COD/mg COD, respectively. The average ratio of the $Y_H$ for aerobic reactors to those for the anoxic reactors were about 1:0.79 for the $A^2/O$ process, and about 1:0.69 for the 4-stage BNR process. The experimental method for anoxic and anaerobic $Y_H$ estimation shown in this study has turned out to be simple and efficient in its practical application.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.268-272
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• 2003

Experiments were carried out to investigate the selection of industrial medium and optimization of fermentation process for the production of erythritol by Candida magnoliae SR101. In the batch fermentation, light steep water(LSW) was the best nitrogen source for the industrial production of erythritol. For the optimization of culture condition, the batch culture was performed. When the concentration of LSW was 65 mL/L in the defined medium containing 250 g/L of glucose, 44% of erythritol yield with 110 g/L of erythritol concentration and 0.66 g/L-hr of productivity, respectively were obtained. Two-stage fed-batch culture was performed to improve the volumetric productivity of erythritol. High density cell culture in the growth stage was performed by batch type with 100 g/L glucose and 500 mL/L LSW concentration, respectively. The cell yield was 0.72 g-cell/g-glucose. Productivity of erythritol was increased and concentration of organic acids such as gluconic acid and acetic acid were decreased when initial pH of 6.5 controlled by 28% ammonia water For increasing yield of erythritol, glucose concentration in the production stage was tested. 37% of total erythritol yield with 186 g/L of erythritol concentration and 1.66 g/L-hr of erythritol productivity were obtained when 820 g of glucose powder was directly added for making up 450 g/L of glucose at production stage.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.732-738
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• 2008

Simulated moving bed (SMB) process is a continuous chromatographic technology used to separate a large amount of petrochemicals, fine chemicals, pharmaceuticals, and so on, drawing a great attraction of related industries. With the recent development of biotechnology, the SMB process has been adopted for the separation of various useful bio-products. Attempts to understand the separation mechanism of the SMB process in many aspects are reported in many publications. These researches have dealt with the improvement of SMB for easier operation and solving problem in process. The feed mixture fed into the SMB process may be of different concentration batch by batch rather than in uniform concentration. Retention behaviors of feed (psicose (A) and fructose (B) mixture) existing in the SMB unit in dynamic steady-state and feed (psicose (C) and fructose (D) mixture) newly injected into the SMB were analyzed. It was observed that the existing components, (A) and (B), were eluted relatively faster as the injection time of new feed was earlier during the port-switching period. In addition, the components (C) and (D) were eluted earlier as fresh feed was injected earlier in a port-switching time.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.2
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• pp.71-77
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• 1998

The strain of Serratia marcescens QM B1466 produces selectively large amount of chitinolytic enzymes (about 1mg/L medium). Enzymatic hydrolysis of chitin to N-acetyl-${\beta}$-D-glucosamine (NAG) was performed with a system consisting of two hydrolases (chitinase and chitobiase) produced by optimization of a microbial host consuming chitin particles. For the development of Large-scale biological process for the production of NAG from chitinaceous waste, the selection and optimization of a microbial host, particle size of crab/shrimp chitin sources and initial induction time using chitin as a sole carbon source on chitinase/chitobiase production and NAG production were examined. Crab-shell chitin(1.5%) treated by dilute acid and , ball-milled with a normal diameter less than 250m gave the highest chitinase activity over a 7 days culture. Crude chitinase/ chitobiase solution obtained in a 10 L fed-batch fermentation showed a maximum activities of 23.6 U/mL and 5.1 U/mL, respectively with a feeding time of 3 hrs, near pH 8.5 at 30$^{\circ}C$.