• Journal of Life Science
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• v.8 no.5
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• pp.497-503
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• 1998

Cyclodextrinase from B. stearothemophilus KJ16 that can produce both cyclodextrin(CD) glucanotransferase and cyclodextrinase was purified 87.6-fold with 7% yield by ammonium sulfate precipitation, DEAE-cellulose chromatog-raphy, Sephadex G-100 chromatography, and FPLC. The molecular weight of the purified enzyme was about 68,000 dalton by SDS-PAGE. The optimal pH and temperature were 6.0 and 55$^{\circ}C$, respectively. The enzyme was stable at 5$0^{\circ}C$ for 2 hr in the pH range of 5.5 and 8.5. The enzyme activity was inhibited strongly by mercaptoethanol, di-thiothreitol, p-chloromercuribenzoate, N-bromosuccinimide, $Cu^{+2}$and $Hg^{+2}$. The purified enzyme hydrolyzed CDs with$\gamma$-CD>$\beta$-CD>$\alpha$-CD. The enzyme also hydrolyzed linear maltodextrins and polysaccharides, but the rates of hyd-rolysis for such substrates were slow as compared to that for $\gamma$-CD. The final degradation products with all substrates were maltose and glucose. Maltose was not further hydrolyzed.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.45-52
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• 2009

Naphthalene-degrading bacteria Pseudomonas aeruginosa CZ6 isolated from contaminated soil can adhere to crystal naphthalene and produce extracellular polymeric substance. LB, YM and MSM medium were used as culture mediums to investigate the formation of biofilm. Biofilm was developed the most in LB medium by Pseudomonas aeruginosa CZ6. In the culture, strain CZ6 growth was rarely affected by naphthalene concentration. Optimal culture condition was $30^{\circ}C$ and pH 7 at 0.10% substrate and 150 rpm shaking. The effect of culture medium on naphthalene degradation in the two soil slurry system was evaluated. The initial degradation rate of naphthalene was highest in the MSM medium of soil slurry. However, the sorbed naphthalene was rapidly degraded at the LB medium when naphthalene availability in liquid was limited. The results of this study suggest that biofilm formation and extracellular polymeric substance production increased bioavailability of soil sorbed naphthalene.

• Korean journal of food and cookery science
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• v.13 no.5
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• pp.623-626
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• 1997

The purpose of this study was to investigate the properties of proteolytic enzymes extracted from mulberry (Morus alba L.). The protease activity of the enzymes from mulberry was 2,358 unit/g. The enzymes showed strong activities toward hemoglobin and collagen. The optimum temperature and pH of the enzymes were 50$^{\circ}C$ and 6.0, respectively. The enzymes were stable at the temperature range of 30$^{\circ}C$ to 60$^{\circ}C$ and the pH from 5.0 to 7.0 for 1 hr at 37$^{\circ}C$ of incubation and also retained whole activity after incubation for 1 hr at 60$^{\circ}C$.

• Journal of the Korean Wood Science and Technology
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• v.29 no.4
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• pp.67-78
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• 2001

Two species(Quercus mongolica, populus euramericana) of hardwood chips were subjected to steam explosion 25 kg/$cm^2$, for 6 min. The exploded woods were treated by the single or multi-stage chemical process with sodium hydroxide, sodium hypochlorite and sodium chlorite. The multi-stage treatment of exploded wood can be successfully removed lignin. Enzymatic hydrolysis rate of substrate varied from 25% for exploded wood to about 80% for the multi-chemical treated exploded wood. The enzymatic susceptibility was different among wood species. The multi chemical treatment of the exploded wood resulted in the high rate of glucose in the enzymatic hydrolyzate. Cellulase adsorption increased at high lignin content of substrates, while crystallinity, pore area and specific surface area of substrates did not affected enzyme adsorption. According to the proposed pretreatment and saccharification process in this study, it can be acquired about 37~40 kg of glucose from 100 kg of hardwood.

• Journal of the Korean Chemical Society
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• v.34 no.3
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• pp.221-226
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• 1990

The solvolysis of substitued phenacyl tosylates was studied in binary solvent mixtures of methanol-acetonitrile and methanol-acetone at 55$^{\circ}C$. Except for m-nitrophenacyl tosylate, the rate constants were increased with both of electron-donating substituents and electron-withdrawing ones and its rate constants were the largest in the binary solvent mixtures of 90% MeOH-10% MeCN. The results show that the reactions were changed with dissociative $S_N2$ mechanism judging from the magnitude of 1/m values going from the electron-withdrawing group to the electron-donating one of the substrate. And above results were consisted with the account for the PES model and QM approach.

• Journal of Soil and Groundwater Environment
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• v.8 no.4
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• pp.45-52
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• 2003

A gas-substrate degrading bacterium, Nocardia SW3, was isolated from the gasoline contaminated aquifer using propane and butane as carbon and energy sources. We have examined the effects of substrate concentration, temperature and pH on the gas substrate degradation as well as MTBE cometabolic degradation. The result for the effect of substrate concentration showed that the maximum degradation rates of propane and butane were 30.6 and 25.4 (n㏖/min/mg protein) at 70 $\mu$㏖, respectively. The optimum temperature and pH for the degradation of gas substrate were $30^{\circ}C$ and 7, respectively. Substrate degradation activity, however, was still active in broad range of pH from 5 to 8 and temperature between $15^{\circ}C$and$35^{\circ}C$. The degradation activity of Nocardia SW3 for the MTBE was similar to the both substrates. The observed maximal transformation yields ($T_y$) were 46.7 and 35.0 (n㏖ MTBE degraded $\mu$㏖ substrate utilized), and the maximal transformation capacities ($T_c$) were 320 and 280 (n㏖MTBE degraded/mg biomass used) for propane and butane oxidizing activity on MTBE, respectively. And also, TBA was detected as by-product of MTBE and it was continuously degraded further.

• Microbiology and Biotechnology Letters
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• v.30 no.4
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• pp.395-401
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• 2002

Methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) have been widely used as solvents in various industries. Biodegradation of MEK and MIBK by Pseudomonas putida KT-3, which could utilize MEK or MIBK as a sole carbon source, was characterized, and the cosubstrate interaction in MEK/MIBK mixture was also studied. Within the range of initial MEK concentration (from 0.5 to 5.5 mM), an increased substrate concentration increased the specific degradation rate of MEK by P putida KT-3 (from 3.15 to 10.58 mmol/g DCW$\cdot$h), but the rate sightly increased at 11.0 mM of initial MEK concentation (11.28 mmol/g DCW$\cdot$h). The similar degradation rates of MIBK (4.69-4.92 mmol/g DCW$\cdot$h) were obtained at more than 3.0 mM of initial MIBK concentation. Kinetic analysis on the degradation of MEK/MIBK mixture by P. putida KT-3 showed that MEK or MIBK acted as a competitive inhibitor. Maximum degradation rate ($V_{max}$), saturation constant ($K_{m}$) and inhibition constant ($K_{1}$) were as follows: $V_{max,MEK}$=12.94 mmol/g DCW$\cdot$h; $K_{m,MEK}$=1.72 mmol/L; $K_{l,MEK}$=1.30 mmol/L; $V_{max,MIBK}$=5.00 mmol/g-DCW$\cdot$h; $K_{m,MIBK}$=0.42 mmol/L; $K_{l,MEK}$=0.77 mmol/L.

• Food Science of Animal Resources
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• v.31 no.1
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• pp.129-138
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• 2011

Hydrolyzed wheat gluten (HWG) and low glutamic acid (Glu) hydrolyzed wheat gluten with different quantities of NaCl were reacted with several precursors to develop natural meat flavor based on Maillard reaction products (MRP). The MRP based flavors were analyzed for their pH, browning index, DPPH radical scavenging effect, and sensory properties. Synthetic meat flavor from low Glu hydrolyzed wheat gluten with 7% NaCl and ribose, cysteine, methionine, thiamin, lecithin, and garlic powder reacted at $140^{\circ}C$ for 30 min and were most favorable for a roasted meat flavor. Based on an omission test, cysteine was selected as the most important precursor for producing meat flavor compared to methionine, thiamine, and lecithin. Natural precursors including mushroom powder and fat medium were applied to compensate for the synthetic precursors. The optimum formula for meat flavor was 5% ribose, 7.7% cysteine, 6.9% garlic juice powder, 2.1% Lentinusedodes powder digested with protease, and 1% lard. The sulfuric pungent, oily, and salty attributes of the formula decreased and a mild roasted meat flavor was expressed.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1851-1859
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• 2000

Crude oil-degrading bacteria were isolated from the sites contaminated by oil products. The isolates were identified as Acinetobacter sp. A132, Pseudomonas putida A422, Pseudomonas aeruginosa F721, F722, and Xanthomonas maltophilia B823. The results of investigation on the degradability of crude oil indicated that the strain A132 had the highest rate of $6.04g/L{\cdot}day$. Also, the strain A132 and F722 almost degraded each of n-alkane compounds between $nC_{10}$ and $nC_{32}$. The strain A422 degraded benzene and xylene but not n-alkane. The strain B823 grew somewhat in crude oil but did not entirely degrade other substrates used in this study. The results of the GC/FID analysis on the degradability of the mixed n-alkane compounds showed that the strain F722 could degrade 100% of the compounds with $nC_7{\sim}nC_{10}$ and more than 80% of those with $nC_{11}{\sim}nC_{24}$.

• KSBB Journal
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• v.17 no.4
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• pp.321-325
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• 2002

Chiral epoxides are valuable intermediates for the asymmetric synthesis of enantiopure bioactive compounds. Microbial epoxide hydrolases (EHs) are newly discovered enzymes and versatile biocatalysts for the preparation of chiral epoxides by enantioselective hydrolysis of cheap and easily available racemic epoxide substrates. EHs are commercially potential biocatalysts due to their characteristics such as high enantioselectivity, cofactor-independent catalysis, and easy-to-Prepare catalysts. In this Paper, recent progresses in biochemistry and molecular biology of EH and developments of novel reaction systems are reviewed to evaluate the commercial feasibility of EH-catalyzed hydrolytic kinetic resolution for the production of chiral epoxides.