• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.253-253
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• 2010

Rice straw was pretreated with aqueous ammonia in order to enhance enzyme digestibility. Soaking in ammonia aqueous (SAA) was conducted with 15% ammonia, at $60^{\circ}C$. for 24 h. Optimization of both saccharification conditions and enzyme loading of SAA rice straw was carried out. Especially enzyme loading test was performed using statistical method. Moreover proton beam irradiation (PBI) was also performed to overcome the problem which inhibit the enzyme digestibility at 1-25 kGy doses with 45 MeV of beam energy. Optimal condition for enzymatic saccharification was follows; pH 4.8, $50^{\circ}C$, 60 FPU of enzyme activity, 1:4 ratio of celluase and ${\beta}$-glucosidase. Also, optimal doses of PBI on rice straw and SAA-treated rice straw for efficient sugar recovery were found to be 3 kGy, respectively. When saccharification was performed with optimal condition, glucose conversion yield was 89% of theocratical maximum in 48 h, and 3 kGy of PBI was applied to SAA-treated rice straw, approximately 90% of the theoretical glucose yield was obtained in 12 h. The results of X-ray diffractometry (XRD) support the effect of both SAA and PBI on sugar recovery, and scanning electron microscopy (SEM) images unveiled the physical change of the rice straw surface since rugged rice straw surface was observed.

• KSBB Journal
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• v.27 no.6
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• pp.341-346
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• 2012

Indican (indoxyl-${\beta}$-D-glucoside) is a colorless natural compound and can be used as a precursor for the production of indigo. This production step only require an enzyme, ${\beta}$-glucosidase, that readily screened from microbial resource by using selective media supplemented with indican as a sole carbon source. Agrobacterium tumefaciens was well grown in this media and thus presumed to produce a related enzyme. The corresponding gene, encoding a protein with a calculated molecular mass of 51 kDa, was cloned and overexpressed as MBP fusion proteins. The purified enzyme was determined to be a dimer and showed the maximum activity for indican at pH 7.0 and $40^{\circ}C$. The kinetic parameters for indican, Km and Vmax, were determined to be 1.4 mM and 373.8 ${\mu}M/min/mg$, respectively. The conversion yield of indican into indigo using this enzyme was about 1.7-1.8 folds higher than that of previously isolated enzyme from Sinorhizobium meliloti. Additionally, this enzyme was able to hydrolyze various ${\beta}$-1,4 glycoside substrates.

• Animal Bioscience
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• v.34 no.8
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• pp.1365-1374
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• 2021

Objective: This study was conducted to investigate the synergistic effect of exogenous multienzyme and phytase on growth performance, nutrients digestibility, blood metabolites, intestinal microflora, and morphology in broilers fed corn-wheat-soybean meal diets. Methods: A 2×2 factorial design was used in this study. Four dietary treatments consisted of i) basal diets (corn-wheat-soybean meal based diets without multi-enzyme and phytase), ii) basal diets with phytase (0.05%), iii) basal diets with exogenous multi-enzyme (0.05%), and iv) basal diets with exogenous multi-enzyme including phytase (0.05%). A total of 480 broiler chickens (Ross 308 - one day old) were weighed and allotted to thirty-two cages (15 birds per cage), and chicks were randomly allocated to four dietary treatments. Results: The body weight gain and feed conversion rate were improved by supplementation of exogenous multi-enzyme containing phytase during the finisher period (p<0.05). The birds fed diets with exogenous multi-enzyme containing phytase had a significantly greater digestibility of dry matter, gross energy, crude protein, calcium, and phosphorus compared with birds fed non-supplemented diets (p<0.05). The chickens fed diets with exogenous multi-enzyme containing phytase showed a higher concentration of Ca and P in the serum (p<0.05). The population of Lactobacillus spp., Escherichia coli, and Clostridium were not affected in the ileum and cecum of chickens fed enzyme-supplemented diets. The dietary supplemental exogenous multi-enzyme containing phytase showed a significant improvement in villus height, crypt depth, and villus height and crypt depth ratio, compared to basal diets or dietary supplemental phytase (p<0.05). Conclusion: The supplementation of the exogenous multi-enzyme containing phytase synergistically improved the growth performance, nutrients digestibility, and villus height of the small intestine of broiler chickens fed a corn-wheat-soybean meal based diets.

• The Korean Journal of Mycology
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• v.14 no.3
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• pp.195-200
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• 1986

The enzyme produced by a strain of Rhizopus japonicus was able to covert selectively ginsenoside $Rb_1$ which was the most abundant ginseng saponin, into ginsenoside Rd which was known to be superior to ginsenoside $Rb_1$ pharmaceutically. This specific conversion of ginsenoside $Rb_1$ without any change of other ginsenoside patterns was confirmed by thin layer chromatography and high performance liquid chromatograpy quantitatively. The amount of ginsenoside Rd was increased to 4.8 and 34.7 folds by enzymatic conversion of ginsenoside $Rb_1$ in total saponin and ginsenoside Rb group saponin, respectively. The increased amount of ginsenoside Rd corresponded to total amount of released glucose and decreased amount of ginsenoside $Rb_1$ accurately.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.457-460
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• 2002

In an effort to isolate novel strains expressing a thermostable esterase that hydrolyzed the rac-ketoprofen ethyl ester to ketoprofen in the stereospecific manner, we screened various soils and composts from broad ecological niches in which the activity was expected to be found. Three hundreds of microbial strains were tested to determine their ester-hydrolyzing activity by using an agar plate containing insoluble tributyrin as an indicative substrate, and then further screened by activity on the (R,S)-ketoprofen ethyl ester. Twenty-six strains were screened primarily at high growth and incubation temperature and further compared the ability to ethyl ester-hydrolyzing activity in terms of conversion yield and chiral specificity. Consequently, a strain JYl44 was isolated as a novel strain that produced a (R)-stereospecific esterase with high stability and systematically identified as a Bacillus stearothermophilus JY144. The enzyme indeed stables at a broad range of temperature, upto 65 $^{\circ}C$, and pH ranging from 6.0 to 10.0. The optimal temperature and pH for enzymatic conversion were 50 $^{\circ}C$ and 9.0, respectively. Based on the observations that resulted a poor cell growth, and enzyme expression in wild type strain, we further attempted the gene cloning into a general host Escherichia coli and determined its primary structure, concomitantly resulting a high level expression of the enzyme. The cloned gene had an open reading frame (250 amino acids) with a calculated molecular mass of 27.4 kDa, and its primary structure showed a relative high homology (45-52 %) to the esterases from Streptomyces and Bacillus strains. The recombinant whole cell enzyme could efficiently convert the rac-ketoprofen ethyl ester to (R)-ketoprofen, with optical purity of 99 % and yield of 49 %.

• Applied Biological Chemistry
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• v.28 no.4
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• pp.233-238
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• 1985

Glucoamylases catalyze a stepwise hydrolysis of starch with the production of glucose. In order to make an efficient conversion of starch into glucose, glucoamylases prepared from Rhizopus spp. (Sigma Co.) were attached to a porous glass and immobilized by glutaraldehyde-induced crosslinking. The porous glass used in this study was $ZrO_2$ coated, $40{\sim}80$ mesh, 550 A pore diameter. Using the forgoing glass, we could couple as much as 50mg of protein per gram of carrier. Substrate for the glucoamylase was an enzyrne-modified thin-toiling 30% cornstarch solution used where greater solubility and low viscosity are desired. Immobilized glucoamylase had an optimum pH 7.0 to the alkaline side of soluble enzyme. Km values of immobilized and soluble enzyme were 1.04 mM and 1.25mM, respectively. The thermal stability of glucoamylase was increased by immobilization and the immobilized enzyme showed an optimum temperature at $40{\sim}60^{\circ}C$. The continuous conversion of cornstarch to glucose by use of immobilized glucoamylase resulted in the production of a more than 90 DE product.

• Journal of Microbiology and Biotechnology
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• v.31 no.3
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• pp.419-428
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• 2021

To efficiently recycle GH78 thermostable rhamnosidase (TpeRha) and easily separate it from the reaction mixture and furtherly improve the enzyme properties, the magnetic particle Fe3O4-SiO2-NH2-Cellu-ZIF8 (FSNcZ8) was prepared by modifying Fe3O4-NH2 with tetraethyl silicate (TEOS), microcrystalline cellulose and zinc nitrate hexahydrate. FSNcZ8 displayed better magnetic stability and higher-temperature stability than unmodified Fe3O4-NH2 (FN), and it was used to adsorb and immobilize TpeRha from Thermotoga petrophilea 13995. As for properties, FSNcZ8-TpeRha showed optimal reaction temperature and pH of 90℃ and 5.0, while its highest activity approached 714 U/g. In addition, FSNcZ8-TpeRha had better higher-temperature stability than FN. After incubation at 80℃ for 3 h, the residual enzyme activities of FSNcZ8-TpeRha, FN-TpeRha and free enzyme were 93.5%, 63.32%, and 62.77%, respectively. The organic solvent tolerance and the monosaccharides tolerance of FSNcZ8-TpeRha, compared with free TpeRha, were greatly improved. Using naringin (1 mmol/l) as the substrate, the optimal conversion conditions were as follows: FSNcZ8-TpeRha concentration was 6 U/ml; induction temperature was 80℃; the pH was 5.5; induction time was 30 min, and the yield of products was the same as free enzyme. After repeating the reaction 10 times, the conversion of naringin remained above 80%, showing great improvement of the catalytic efficiency and repeated utilization of the immobilized α-L-rhamnosidase.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.9
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• pp.1354-1360
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• 2006

Maize-soybean meal diets with 0, 100, 200 and 300 g/kg double zero rapeseed meal ('00' RSM) with and without an enzyme mixture (xylanase, pectinase, cellulase) at a level of 1.6 g/kg were evaluated with 624 day-old broiler chicks for 5 weeks. The birds were randomly allocated to eight dietary treatments with three replicates of 26 birds each. Average daily gain (ADG) and feed intake (FI) were recorded weekly and ileal viscosity, organ weights, serum enzyme activity, hormonal profile and hematological parameters were measured at the end of week 5. Average daily gain during the weekly periods was significantly influenced by the dietary level of '00'RSM (p<0.01). Inclusion of '00' RSM improved the ADG up to day 28 with the increased level; beyond that time no improvement was recorded when compared to control groups. However, ADG from 1-35 days was significantly different between 300 g/kg inclusion level of '00' RSM and the control diet. Inconsistent decline in feed intake and feed conversion ratio was observed up to day 21 and the trend was reversed thereafter. The proportion of '00' RSM in the diet had a significant ($p{\leq}0.05$) influence on thyroid weight but had no effect on the relative weights of liver and heart, serum enzyme activities (${\gamma}$-glutamyl transferase, alanine amino transferase and aspartate amino transferase), thyroid hormones ($T_3$ and $T_4$), hemoglobin level and hematocrit. Significant improvement in ADG was recorded during the 2nd week of age with the addition of enzyme, whereas for all other periods, including the whole period of the trial, higher but non-significant ADG was observed. FI and FCR were not affected by the addition of enzyme but there was a numerical reduction in FCR during the whole period. The addition of enzyme reduced the ileal viscosity at all levels of '00' RSM inclusion. The results suggest that '00' RSM can be included up to 300 g/kg in broiler diets without any adverse effects on health and performance. The addition of commercial enzyme mixture containing xylanase, pectinase, cellulase to broiler diets containing '00'RSM has some effect on growth rate and feed conversion efficiency.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.131-141
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• 2009

The conversion of carbon dioxide to value-added compounds has been attracted to solve the environmental problems due to the climate change caused by greenhouse effect in addition to recycle the abundant and renewable carbon source. For utilizing carbon dioxide to useful compounds, the development of catalysts and optimization of experimental conditions are indispensable since carbon dioxide is the most stable one among carbon compounds and the a certain amount of energy is required for the carbon dioxide conversion. The technologies developed for the electrochemical carbon dioxide conversion were reviewed in terms of electrocatalyst which can be electrode material, inorganic complex, and enzyme. This field should be developed further since no good catalyst having selectivity, efficiency, and stability all together.

• The Korean Journal of Food And Nutrition
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• v.6 no.3
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• pp.158-168
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• 1993

For the conversion of WAD to NADP, Immobilized Brevibacterium ammoniagenes cells with NAD kinase was coupled with ATP-generating system by acetate kinase. The membrane permeability of B. ammoniagenes was improved by toluene treatment of cells. The toluene treated B. ammoniagenes cells were immobilized for stable enzyme activity. Partially purified acetate kinase was used in the reaction system. The optimum conditions for the efficient conversion of UAD to WADP by energy-coupled system were investigated. B. ammoniagenes cells treated with toluene for the Improvement of membrane permeability showed 4.5 fold improved permeability in the conversion of NAD to NADP compared with Intact cells. 3% k-carrageenan as the immobilization matrix of B. ammoniagenes showed the best efficiency for the conversion of NAD to NADP The optimum conditions for the WAR to WARP conversion reaction coupled nth ATP-generating system were 10mM acetylphosphate, 5mM ADP 200mM inorganic phosphate, 10mM MgCl2, 250mg/ml Immobilized cells, 49.3mUnit/ml acetate kinase, pH 7.5 and 37$^{\circ}C$. Under the optimum conditions, 72% of 5mM(340mg/ml ) NAD was converted to UADP In 12 hours.