• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.2
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• pp.51-58
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• 2016

In the Integrated Two-Phase Anaerobic Digestion (ITPAD) process, acid and methane fermentation take place in one reactor, which has advantages to cope with organic load variation and reduce foot-print required, compensating disadvantages of Conventional Separated Two-Phase Anaerobic Digestion (CSTPAD). In the present work, organic matter degradation efficiency and biogas generation amount and other performance parameters of the ITPAD fed with food waste leachate were analyzed. In addition, feasibility study on the ITPAD method was performed by comparing its digestion efficiency with that of the CSTPAD. Organic matter alteration and biogas generation of the integrated method were examined for approximately 130 days based on the 5ton/day scaled pilot plant. Experiment results revealed that organic matter removal rate was 80% for mean food waste leachate input amount of $4.1m^3/day$. The biogas generation rate was $63.0m^3$ per ton of food waste leachate input, corresponding to the input VS amount of $0.724m^3/kg-VS_{added}$, and methane content of generated biogas was approximately 61.3%. The ITPAD has a comparable or higher organic matter removal efficiency compared to the conventional separated two-phase anaerobic digestion method. Consequently, the ITPAD method has a great need to commercialize a food waste leachate treatment technology against highly concentrated organic waste leachate.

• The Plant Pathology Journal
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• v.33 no.3
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• pp.337-344
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• 2017

To develop a commercial product using the mycoparasitic fungus Simplicillium lamellicola BCP, the scale-up of conidia production from a 5-l jar to a 5,000-l pilot bioreactor, optimization of the freeze-drying of the fermentation broth, and preparation of a wettable powder-type formulation were performed. Then, its disease control efficacy was evaluated against gray mold diseases of tomato and ginseng plants in field conditions. The final conidial yields of S. lamellicola BCP were $3.3{\times}10^9conidia/ml$ for a 5-l jar, $3.5{\times}10^9conidia/ml$ for a 500-l pilot vessel, and $3.1{\times}10^9conidia/ml$ for a 5,000-l pilot bioreactor. The conidial yield in the 5,000-l pilot bioreactor was comparable to that in the 5-l jar and 500-l pilot vessel. On the other hand, the highest conidial viability of 86% was obtained by the freeze-drying method using an additive combination of lactose, trehalose, soybean meal, and glycerin. Using the freeze-dried sample, a wettable powder-type formulation (active ingredient 10%; BCP-WP10) was prepared. A conidial viability of more than 50% was maintained in BCP-WP10 until 22 weeks for storage at $40^{\circ}C$. BCP-WP10 effectively suppressed the development of gray mold disease on tomato with control efficacies of 64.7% and 82.6% at 500- and 250-fold dilutions, respectively. It also reduced the incidence of gray mold on ginseng by 65.6% and 81.3% at 500- and 250-fold dilutions, respectively. The results indicated that the new microbial fungicide BCP-WP10 can be used widely to control gray mold diseases of various crops including tomato and ginseng.

• Journal of Microbiology and Biotechnology
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• v.25 no.10
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• pp.1742-1750
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• 2015

Human insulin is composed of 21 amino acids of an A-chain and 30 amino acids of a B-chain. This is the protein hormone that has the role of blood sugar control. When the recombinant human proinsulin is expressed in Escherichia coli, a serious problem is the formation of an inclusion body. Therefore, the inclusion body must be denatured and refolded under chaotropic agents and suitable reductants. In this study, H27R-proinsulin was refolded from the denatured form with β-mercaptoethanol and urea. The refolding reaction was completed after 15 h at $15^{\circ}C$, whereas the reaction at $25^{\circ}C$ was faster than that at $15^{\circ}C$. The refolding yield at $15^{\circ}C$ was 17% higher than that at $25^{\circ}C$. The refolding reaction could be carried out at a high protein concentration (2 g/l) using direct refolding without sulfonation. The most economical and optimal refolding condition for human preproinsulin was 1.5 g/l protein, 10 mM glycine buffer containing 0.6 M urea, pH 10.6, and 0.3 mM β-mercaptoethanol at $15^{\circ}C$ for 16 h. The maximum refolding yield was 74.8% at $15^{\circ}C$ with 1.5 g/l protein. Moreover, the refolded preproinsulin could be converted into normal mature insulin with two enzymes. The average amount of human insulin was 138.2 g from 200 L of fermentation broth after enzyme reaction with H27R-proinsulin. The direct refolding process for H27R-proinsulin was successfully set up without sulfonation. The step yields for refolding and enzyme reaction were comparatively high. Therefore, our refolding process for production of recombinant insulin may be beneficial to the large-scale production of other biologically active proteins.

• Korean Journal of Food Science and Technology
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• v.23 no.6
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• pp.683-688
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• 1991

Wheat flour was extruded by a single-screw extruder, and used for the ethanol production of takju. The molecular structure and enzymic susceptability of extruded starch were compared to those of steam cooked one. The gel permeation chromatographic pattern of wheat flour extrudates was not significantly different from those of raw and steam cooked starches. However, the conversion rate of extruded starch into maltose by ${\alpha}-amylase$ hydrolysis was significantly faster than those of raw ad steamed starch. The molecular weight of starch estimated from GPC pattern and the intrinsic viscosity were remarkably reduced by extrusion cooking followed by the enzymic hydrolysis for 30 min, while steam cooking and enzymic hydrolysis for 30 min did not change them significantly. Extrusion-cooked flour produced alcohol 26% higher than that of steamed flour in the laboratory takju fermentation, and 10% more alcohol in the pilot plant scale takju production.

• Journal of Microbiology and Biotechnology
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• v.27 no.5
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• pp.947-955
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• 2017

Herbicidin A is a potent herbicide against dicotyledonous plants as well as an antibiotic against phytopathogens. In this study, fermentation parameters for herbicidin A production in submerged culture of Streptomyces scopuliridis M40 were investigated. The herbicidin A concentration varied with the C/N ratio. High C/N ratios (>4) resulted in a herbicidin A production of more than 900 mg/l, whereas maximally 600 mg/l was obtained at ratios between 1 and 3.5. In 5-L batch fermentation, there was a positive correlation between the oxygen uptake rate (OUR) and herbicidin A production. Once the OUR increased, the substrate consumption rate increased, leading to an increase in volumetric productivity. Mechanical shear force affected the hyphal morphology and OUR. When the medium value of hyphal size ranged from 150 to $180{\mu}m$, high volumetric production of herbicidin A was obtained with OUR values >137mg $O_2/l{\cdot}h$. The highest herbicidin A concentration of 956.6 mg/l was obtained at 500 rpm, and coincided with the highest relative abundance of hyphae of $100-200{\mu}m$ length and the highest OUR during cultivation. Based on a constant impeller tip speed, which affects hyphal morphology, herbicidin A production was successfully scaled up from a 5-L jar to a 500-L pilot vessel.

• KSBB Journal
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• v.14 no.1
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• pp.114-118
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• 1999

In order to use a polysaccharide, curdlan, as a concrete admixture, we first developed a pilot-scale fermentation process for the mass production of curdlan. We also examined the rheological properties of curdlan, and tested how well the curdlan obtained in this work increased the segregational resistance of the cement slurry. Fermentation was performed in a 300-liter fermenter equipped with 3 disk-turbine impellers. Since curdlan production is stimulated under nitrogen-limiting conditions, the culture pH was shifted from the optimal pH for cell growth (pH 7.0) to the optimal pH for curdlan production (pH 5.5) at the onset of ammonium exhaustion. We obtained a curdlan production of 65 g/L in 120 hr batch cultivation of Agrobacterium species. The insoluble curdlan at the final stage of fermentation was readily harvested by centrifugation together with the cells. The freeze-dried sample contained 78% (w/w) of curdlan. The solubility and viscosity of the curdlan increased with the increase of the solution pH, which enhances the viscosity of concrete since the pH of concrete is extremely high (pH 13.0). Test results of the curdlan as a concrete admixture with cement slurry demonstrated that it prohibits the leakage of water. In conclusion, this work certifies and enlarges curdlan's industrial potential as a concrete admixture.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.103-110
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• 2003

Stable production of fermented kanjang containing 1.8% (v/v) ethanol was obtained within four days using traditional kanjang containing 4% added glucose in packed-bed bioreactor systems filled with immobilized Zygosaccharomyces rouxii and Candida versatilis on porous alumina ceramic bead carrier at $28{\pm}0.5^{\circ}C$ and aeration rate of 0.05 vvm. Specific rates of alcohol production for Z. rouxii and C. versatilis were 0.0033 and 0.0031/day, respectively, and those of glucose consumption were both -0.0087/day in the batch type of alcoholic fermentation. In semi-continuous alcoholic fermentation at a dilution rate of 0.25/day, specific rates of alcohol production for Z. rouxii and C. versatilis were 0.0045 and 0.0029/day, and those of glucose consumption were -0.01 and -0.008/day, respectively, using identical bioreactor system. Similar specific rates of alcohol production were observed both in the batch or semi-continuous process and in the continuous one at the dilution rate of 0.25/day. Sensory characteristics of all alcoholic-fermented kanjang by Z. rouxii, C. versatilis, and a mixture of both yeasts (2:1, w/w) were shown to be significantly superior to those of home-made kanjang as revealed through organoleptic evaluation tests (p<0.05).

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.344-357
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• 2020

Strain improvement and bioprocess development were undertaken to enhance hyaluronic acid(HA) production by Streptococcus zooepidemicus cells. Using a high-yielding mutant strain, statistical medium optimization was carried out in shake flask cultures, resulting in 52% increase in HA production (5.38 g/l) at the optimal medium composition relative to the parallel control cultures. For sufficient supply of dissolved oxygen (DO), which turned out to be crucial for enhanced production of HA, agitation system and speed were intensively investigated in 5 L bioreactor cultures. Increase in oxygen mass transfer coefficient (k_La) through increment of agitation speed (rpm) and 35% expansion of diameter of the newly-designed impellers showed significantly positive effects on HA production. By installing an expanded Rushton-turbine impeller for efficient break-down of sparged air, and an extended marine impeller above the Rushton-turbine impeller for efficient mixing of the air-born viscous fermentation broth, maximum amount of HA (9.79 g/l) was obtained at 450 rpm, 1.8 times higher level than that of the corresponding flask culture. Subsequently, the possibility of bioprocess scale-up to a 50 L bioreactor was investigated. Despite almost identical maximum HA production (9.11 vs 9.25 g/l), the average HA volumetric productivity (r_p) of the 50 L culture turned out only 74% compared to the corresponding 5 L culture during the exponential phase, possibly caused by shear damages imposed on the producing cells at the high stirring in the 50 L culture. The scale-up process could be successfully achieved if a scale-up criterion of constant oxygen mass transfer coefficient (k_La) is applied to the 50 L pilot-scale bioreactor system.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.12
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• pp.865-872
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• 2014

The study was conducted to evaluate the effect of addition of food waste in brown water for anaerobic hydrogen production. Batch experiment was carried out to determine appropriate food waste to brown water mixing ratio. Maximum hydrogen yield of $6.92mmol\;H_2/g\;COD_{removed}$ was obtained at 70% food waste and 30% brown water. Semi-pilot scale reactor was operated based on result of batch experiment. Semi-pilot reactor operated, mixing 70% food waste and 30% brown water showed significant increment in butyric acid concentration. B/P (Butyric to propionic acid ratio) which is considered as governing factor for hydrogen production was found high (52.64). Maximum hydrogen yield of $25.03mmol\;H_2/g\;COD_{removed}$ was obtained. Result of this study concluded that mixing of food waste to brown water at appropriate ratio assists in enhanced hydrogen fermentation.

• KSBB Journal
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• v.23 no.4
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• pp.345-349
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• 2008

To enhance the value as a feedstuff of distiller's dried grain (DDG) and develop fermented feedstuff, we investigated the effects of the culture conditions affecting glucoamylase activity, such as pH in submerged culture and moisture content in solid-state culture. Also, we investigated the optimal mixing ratio of DDG and wheat bran for the production of fermented feedstuff containing high content of amino acids. In culture conditions for high fermented activity, pH and moisture were optimum at pH 4 and 60%, respectively. In the case of mixing ratio, the glucoamylase activity was decreased with increase of DDG content. On the other hand, the content of crude protein was increased slowly. For the development of fermented feedstuff, the optimal mixing ratio of DDG and wheat bran was 1 to 4. Finally, we could produce approximately 1 ton (dry matter) of trial product in incubator of pilot-scale. The glucoamylase activity and the crude protein content were 1,024 U/g and 33.6%, respectively.