• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.2
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• pp.120-132
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• 1993

A continuous hollow fiber membrane reactor(CHFMR) was developed and optimized for the production of yellowfin sole(Limanda aspera) skin gelatin hydrolysates using trypsin. The results were summerized as follows: The $K_m$ value of the CHFMR was 2.4 times higher than that of the batch reactor, indicating reduced enzyme affinity for the substrate. The $K_2$ value of the CHFMR was 8.5 times lower than that of the batch process, showing a significant reduction in trypsin activity in the CHFMR. The optimum operating conditions for the CHFMR process were $55^{\circ}C$, pH 9.0, flux 7.79 ml/min, residence time 77min, and trypsin to substrate ratio, 0.01(w/w) After operating for 60min under the above conditions, $79\%$ of the total amount of initial gelatin was hydrolysed. Enzyme leakage was observed through the 10,000 MWCO membrane after the 20min of reactor operation, while none occurred after 5hr. Total enzyme leakage was about $12.95\%$ at $55^{\circ}C$ for 5hrs. However, there was no apparent correlation between enzyme leakage and substrate hydrolysis. The membrane has a significant effect on trypsin activity loss for 60min of the CHFMR operation. The CHFMR operating with the membrane lost $34\%$ of the initial activity versus a $23\%$ loss of activity after 3hr in the continuous reactor lacking the hollow fiber membrane. The measurement of fouling property showed that relative flux reduction was $91\%$ and flux recover rate was $92\%$ at $10\%$ substrate solution. The productivity(378.85mg product/mg enzyme) of the CHFMR was more than 4 times higher than that of the batch reactor at $55^{\circ}C$.

• Food Science and Preservation
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• v.24 no.2
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• pp.274-281
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• 2017

The optimization of lactic acid fermentation was conducted to produce an old antler fortified with functional ingredients. For the over-production of gamma aminobutyric acid (GABA), the extract of old antlers (OA) was fermented by Lactobacillus plantarum EJ2015 with 0.5% YE, 1.5% glucose, and 3.5% MSG at $30^{\circ}C$ for 7 days. The lactic acid fermented OA showed high viable cell counts of $2.0{\times}10^8CFU/mL$, pH 6.56 and 0.77% acidity after 7 days. Addition of Auricularia auricula-judae (AAJ) enhanced the cell growth of L. plantarum EJ2014, resulting in higher viable cell counts of $2.0{\times}10^9CFU/mL$ and acid production after fermentation for 1 day. In particular, acidity was greatly decreased after fermentation for 3 days and 1.4% GABA was produced by converting efficiently mono sodium glutamate as a substrate. Fermented OA/AAJ mixture indicated the reduced cytotoxicity compared with that of unfermented OA. The fermented OA/AAJ mixture indicated anti-inflammatory effect with less production of NO in microphage cells. The production of NO dropped to $17.75{\mu}M$ at 4 mg/mL, and to $5.58{\mu}M$ at 6 mg/mL old antler after fermentation. Thus, lactic acid fermented OA with AAJ could fortify GABA, probiotics and dietary fiber.

• Journal of Microbiology and Biotechnology
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• v.27 no.4
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• pp.775-784
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• 2017

A neutral xylanase (CcXyn) was identified from Coprinus cinereus. It has a single GH10 catalytic domain with a basic amino acid-rich extension (PVRRK) at the C-terminus. In this study, the wild-type (CcXyn) and C-terminus-truncated xylanase ($CcXyn-{\Delta}5C$) were heterologously expressed in Pichia pastoris and their characteristics were comparatively analyzed with aims to examine the effect of this extension on the enzyme function. The circular dichorism analysis indicated that both enzymes in general had a similar structure, but $CcXyn-{\Delta}5C$ contained less ${\alpha}-helices$ (42.9%) and more random coil contents (35.5%) than CcXyn (47.0% and 32.8%, respectively). Both enzymes had the same pH (7.0) and temperature ($45^{\circ}C$) optima, and similar substrate specificity on different xylans. They all hydrolyzed beechwood xylan primarily to xylobiose and xylotriose. The amounts of xylobiose and xylotriose accounted for 91.5% and 92.2% (w/w) of total xylooligosaccharides (XOS) generated from beechwood by CcXyn and $CcXyn-{\Delta}5C$, respectively. However, truncation of the C-terminal 5-amino-acids extension significantly improved the thermostability, SDS resistance, and pH stability at pH 6.0-9.0. Furthermore, $CcXyn-{\Delta}5C$ exhibited a much lower $K_m$ value than CcXyn (0.27 mg/ml vs 0.83 mg/ml), and therefore, the catalytic efficiency of $CcXyn-{\Delta}5C$ was 2.4-times higher than that of CcXyn. These properties make $CcXyn-{\Delta}5C$ a good model for the structure-function study of $({\alpha}/{\beta})_8$-barrel-folded enzymes and a promising candidate for various applications, especially in the detergent industry and XOS production.

• Journal of Plant Biology
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• v.35 no.1
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• pp.91-95
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• 1992

Changes of contents of reducing sugar and sucrose and activities of sucrose-phosphate synthase, sucrose synthease and invertase from the leaves of barley (Hordeum vulgare L. cv. Chalssal) seedlings grown at $4^{\circ}C$ were investigated, and the property of acid invertase were also examined. In the seedlings grown at $4^{\circ}C$ for 3 days, the contents of reducing sugar and sucrose were increased to 1.3 and 2.4 times, respectively. Activity of acid invertase was decreased markedly by cold treatment while the activities of sucrosephosphate synthase, sucrose synthase, and alkaline invertase were not changed. In acid phosphatase purified partially by ammonium sulfate fractionation and DEAE-Sephacel column chromatography, the $K_m$ value for sucrose was 9.5 mM and the optimum pH and temperature was 5.5 and $35^{\circ}C$ respectively. This enzyme was supposed to be ${\beta}-fructosidase$ by studies on the substrate specificity and the molecular weight was estimated to be 63 Kd by Sephadex G-200 gel chromatography.graphy.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.263-266
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• 2000

The purified biosurfactant $3.16g/{\ell}$ was obtained after cultivation for 104hr at $25^{\circ}C$ with an optimal agitation speed of 200rpm, an aeration rate of 2vvm in a $14{\ell}$ fermenter containing $5.5{\ell}$ of LB medium and 1%(w/v) olive oil as a carbon source. For the kinetic studies, the optimal substrate concentration was analyzed on different olive oil concentrations(0.1, 0.5, 1.0, 1.5, 2.0%(w/v)) and optimal culture conditions(MLBM, 200rpm, 2vvm at $25^{\circ}C$) in a $14{\ell}$ jar fermenter. The results obtained indicate that $K_s$=0.0086 $g/{\ell}$, $q_s$= 0.664 $g/g{\cdot}h$, $q_p$= $4.2{\times}10^{-3}$ $g/g{\cdot}h$, and ${\mu}_{max}$ was determined as $0.1449h^{-1}$.

• Journal of Mushroom
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• v.7 no.1
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• pp.9-21
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• 2009

This study was executed in an attempt to investigate a artificial requisites of fruitbody occurrence. Environmental requirements on habitat for fruitbody occurrence of collected cultures resulted in leading to $13-16^{\circ}C$ and 75% relative humidity, and requiring silt loam of soil texture which had more nutritional substances than a dry field. Optimal temperature was $25^{\circ}C$, medium PDB, and pH 5.0 in cultural conditions. Mannose required of 5% in ASI 59002, 59003, 59004, but 3% in ASI 59001 was selected as optimum carbon source. The substrates stimulating sclerotium formation were cotton waste, or cotton waste + oak sawdust (mixture ratio of 8:2), which had 20% additive of wheat barn respectively. Sclerotium was formed well in the substrate adjusted chemical properties by applying 2% of calcium sulfate. Sclerotium formation was the most effective in the treatment of peat moss + oak sawdust (mixture ratio of 5:5) + 30% of wheat barn.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.2
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• pp.195-200
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• 1992

Rhizopus oryzae CJ-2114 was selected for its strong polygalacturonase activity among various strains of mold found in soil. The optimum pH for the enzyme activity was 4.0 and optimum temperature was 4$0^{\circ}C$. The activation energy for the polygalacturonase was calculated by Arrhenius equation was 2.048㎉/㏖. The reaction of this enzyme followed typical Michaelis-Menten kinetics with the Km value of 54.05mM with the $V_{max}$ of 13.9m mole/min. The enzyme is relatively stable in acidic condition. The activity of polygalactur-onase was inhibited completely by C $u^{2+}$, P $b^{2+}$ and Z $n^{2+}$, $_Mn^{2+}$ at concentration of 1 mM. The enzyme can be inactivated by the treatment with maleic anhydride and iodine. The results indicate the possible involvement of histidine at active site. When polygalacturonase from Rhizopus oryzae CJ-2114 was reacted with poly-galacturonic acid as a substrate mono-, di-, and oligogalacturonic acid were produced at early and mono-, digalacturonic acid produced at late incubation time. time.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1225-1232
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• 2000

This study was carried out to define the effect of electron beam irradiation on the physico-chemical characteristics of sewage sludges. The experimental evidence showed that both pH and alkalinity of irradiated sludge were generally increased as the dose of irradiation increased. It was found that the soluble protein concentration (SPC) and soluble chemical oxygen demand (SCOD) from the sludge right after electron beam irradiation at 3kGy(kilo-joule/kg) increased 2.2 times and 10 times respectively more than those sludges without electron beam treatment. This highly solubilized organics could be resulted in a good soluble substrate for the subsequent anaerobic digestion process. The specific resistance of filtration (SRF) tests showed that sludge dewaterability under electron beam irradiation at 6kGy was found to be 8.8 times higher than that of unirradiated sludge. The sludge dewaterability seemed to be directly related to the dosage of electron beam irradiation up to 10kGy. However, the efficiency of sludge dewaterability tended to be smaller with higher applied irradiation dose. In comparing treatments by different inorganic chemical conditioner with irradiated and unirradiated sludges, it appeared that the dewaterability with irradiated sludge was approximately 4-10 times better that that of unirradiated sludge. Even electron beam treatment itself could replace the result from the sludge conditioned with inorganic chemical coagulants.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.2
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• pp.47-54
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• 1971

The difference in growth rate of p. orientalis cultured on muddy bottom region and sandy bottom region in a pond filled with sea water were studied. For the investigation of the growth rate, the body length and the body weight were determined. Five individuals from each experimental region were sampled in random. The samples were collected at ten-day intervals. The survival rate, the qredator of p. orientalis, and the water conditions during the experimental period were also determined. The results in this study are summerized as follows: 1. The growth rate of p. orientalis which was cultured in the muddy bottom region was greater than that in the sandy bottom region. This is attributable in either case regardless of whether they were cultured with or without food, 2. The relationship between the culturing period (X) and the body length (Y) is : Muddy bottom, Food Y=0.58497X+25.05210 Sandy bottom, Food Y=0.51030X+26.57900 Muddy bottom, No food Y=0.22352X+32.79360 Sandy bottom, No food Y=0.l1418X+31.20740 3. The relationship between the culturing period (X) and the body weight (Y) is : Muddy bottom, Food Y=0.09062X-2.11140 Sandy bottom, Food Y=0.06992X-1.19640 Muddy bottom, No food Y=0.01615X+0.51150 Sandy bottom, No food Y=0.00495X+0.56150 4. When the predator is not present, $84\%$ of P. orientalis may survive. 5. Acanthogobius flavimanus is one of the predator of P. orientalis. 6. It is considered that the variation of water conditions of the pond, in which water had been exchanged 12 times per month, did not affect to the survival rate of P. orientalis.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.2
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• pp.33-41
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• 2005

ZnO epilayer was synthesized by the pulsed laser deposition(PLD) process on Al$_2$O$_3$ subsorte after irradiating the surface of ZnO sintered pellet by ArF(193nm) excimer laser. The epilayers of ZnO were achieved on sapphire(A1203) substrate at the 境mperature of 400$^{circ}$C. The crystalline structure of epilayer was investigated by the Photoluminescence and double crystal X-ray diffraction(DCXD). The carrier density and mobility of ZnO epilayer measure with Hall effect by van der Pauw mothod are $8.27\times$1016cm$^{-3}$ and 299 cm$^{2}$/V$\cdot$s at 293 K respectively, The temperature dependence of the energy band gap of the ZnO obtained from the absorption spectra was well described by the Varshni's relation, E$_g$(T)= 3.3973 eV - ($2.69\times$ 10$^{-4}$ eV/K)T$^{2}$/(T + 463K). After the as-grown ZnO epilayer was annealed in Zn atmospheres, oxygen and vaccum the origin of point defects of ZnO atmospheres has been investigated by the photoluminescence(PL) at 10K. The native defects of V$_{Zn}$, V$_{O}$, Zn$_{int}$, and O$_{int}$ obtained by PL measurements were classified as a donor or acceptor type. In addition we concluded that the heat-treatment in the oxygen atmosphere converted ZnO thin films to an optical p-type. Also, we confirmed that vacuum in ZnO/Al$_2$O$_3$ did not firm the native defects because vacuum in ZnO thin films existed in the form of stable bonds.